Interlocking in Railway Signalling Circiut

CHAPTER- I INTRODUCTION 1.1 Introduction to Interlocking In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it is impossible to display a signal to proceed unless the route to be used is proven safe.

Fig 1.1 Interlocking Types of Interlocking: 1.1.1

Mechanical interlocking

1.1.2

Electro-mechanical interlocking

1.1.3

Relay interlocking

1.1.4

Electronic interlocking

1.2 Signals Signal is a medium to convey a particular pre-determined meaning in non-verbal form.

1

1.2.1 Multiple Aspect Color Light Signal (MACLS): Multiple means more than 2 indications .They may have 3 or 4 different aspects or indications to be given to the driver. These signals have longer range of visibility and Improved reliability. 1.2.2

Classification of CLS:

1.2.3 Manual Stop Signal : Each aspect of the signal is represented by a circle. A horizontal line inside the circle indicates Red aspect, an inclined line the yellow aspect and vertical line the Green aspect. The normal aspect of the signal is shown by double line. 1.2.4 Permissive Signal (Distant Signal) : Shall be located at an adequate distance in rear of the stop signal, the aspect of which it pre- warns. 1.2.5

Automatic Stop Signal : 2

The normal aspect of an automatic signal is green and is indicated by the double vertical line, unlike the manual signal where the normal aspect is red and indicated by double horizontal lines. 1.2.6 Semi-automatic Stop Signal : An illuminated ‘A’ marker distinguishes a semi – automatic signal from a fully automatic signal. Letter ‘A’ against black back ground is illuminated when working as an automatic stop signal and letter ‘A’ extinguished when working as a manual stop signal.

1.2.7 Gate Signal : The Gate stop signal shall be provided with ‘G’ marker. Letter ‘G’ in black on a yellow circular disc.A semi-automatic stop signal interlocked with a level-crossing gate shall be provided with ‘G’ marker disc and an illuminated ‘A’ marker. The ‘A’ marker shall be lit only when the gates are closed and locked against road traffic.

1.3 Microlok-II System: Microlok II interlocking control system is a multi-purpose monitoring and control system which is designed for rail mass transit wayside interlocking functions such as switch machine and signal lamp control, track circuit occupancy monitoring and non vital code line communications. 1.3.1 System Components The Microlok II interlocking control system is a multi-purpose monitoring and control system designed for railroad and rail mass transit wayside interlocking functions such as switch machine and signal lamp control, track circuit occupancy monitoring, and nonvital code line communications. The Components Listed Below: o The system card file o CPU PCB board o Vital inputs and output PCB o Non-vital I/O PCB o Power supply PCB o VCOR Relay 3

o o o o

Address Select PCB EEPROM PCB Terminals Surge Suppressor

CHAPTER -2 LITERATURE SURVEY RELATED WITH TRAINING 2.1 INTERLOCKING 2.1.1 Introduction In railway signalling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signalling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it is impossible to display a signal to proceed unless the route to be used is proven safe.

Fig-2.1 Interlocking An interlock is a device used to prevent undesired states in a state machine, which in a general sense can include any electrical, electronic, or mechanical device or system. In most applications an interlock is used to help prevent a machine from harming its operator or damaging itself by stopping the machine when tripped. 4

2.1.2 Types of Interlocking 2.1.2.1 Mechanical interlocking In mechanical interlocking plants, a locking bed is constructed, consisting of steel bars forming a grid. The levers that operate switches, derails, signals or other appliances are connected to the bars running in one direction. The bars are constructed so that, if the function controlled by a given lever conflicts with that controlled by another lever, mechanical interference is set up in the cross locking between the two bars, in turn preventing the conflicting lever movement from being made. In purely mechanical plants, the levers operate the field devices, such as signals, directly via a mechanical rodding or wire connection. The levers are about shoulder height since they must supply a mechanical advantage for the operator. Cross locking of levers was effected such that the extra leverage could not defeat the locking (preliminary latch lock). The first mechanical interlocking was installed in 1843 at Bricklayers' Arms Junction, England.

Fig-2.2: Mechanical interlocking 2.1.1.1 Electro-mechanical interlocking Power interlockings may also use mechanical locking to ensure the proper sequencing of levers, but the levers are considerably smaller as they themselves do not directly control the field devices. If the lever is free to move based on the locking bed, contacts on the

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levers actuate the switches and signals which are operated electrically or electropneumatically. Before a control lever may be moved into a position which would release other levers, an indication must be received from the field element that it has actually moved into the position requested. The locking bed shown is for a GRS power interlocking machine. 2.1.1.2 Relay interlocking Interlockings effected purely electrically (sometimes referred to as “all-electric”) consist of complex circuitry made up of relays in an arrangement of relay logic that ascertain the state or position of each signal appliance. As appliances are operated, their change of position opens some circuits that lock out other appliances that would conflict with the new position. Similarly, other circuits are closed when the appliances they control become safe to operate. Equipment used for railroad 6ignaling tends to be expensive because of its specialized nature and fail-safe design. Interlockings operated solely by electrical circuitry may be operated locally or remotely with the large mechanical levers of previous systems being replaced by buttons, switches or toggles on a panel or video interface. Such an interlocking may also be designed to operate without a human operator. These arrangements are termed automatic interlockings, and the approach of a train sets its own route automatically, provided no conflicting movements are in progress. GRS manufactured the first all-relay interlocking system in 1929. It was installed in Lincoln, Nebraska on the Chicago, Burlington and Quincy Railroad. Fig-2.3: Relay interlocking

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2.1.2.4 Electronic interlocking Modern interlockings (those installed since the late 1980s) are generally solid state, where the wired networks of relays are replaced by software logic running on special-purpose control hardware. The fact that the logic is implemented by software rather than hardwired circuitry greatly facilitates the ability to make modifications when needed by reprogramming rather than rewiring. In many implementations this vital logic is stored as firmware or in ROM that cannot be easily altered to both resist unsafe modification and meet regulatory safety testing requirements. Fig-2.4: Electronic interlocking

At this time there were also changes in the systems that controlled interlockings. Whereas before technologies such as NX and Automatic Route Setting required racks and racks of relays and other devices, solid state software based systems could handle such functions with less cost and physical footprint. Initially processor driven Unit Lever and NX panels could be set up to command field equipment of either electronic or relay type; however as display technology improved, these hard wired physical devices could be updated with visual display units, which allowed changes in field equipment be represented to the signaller without any hardware modifications. 2.1.1

Forms of Locking 7

2.1.1.1

Electric locking

The combination of one or more electric locks or controlling circuits by means of which levers in an interlocking machine, or switches or other devices operated in connection with signalling and interlocking, are secured against operation under certain conditions.

2.1.1.2

Section locking

Electric locking effective while a train occupies a given section of a route and adapted to prevent manipulation of levers that would endanger the train while it is within that section.

2.1.1.3

Route locking

Electric locking taking effect when a train passes a signal and adapted to prevent manipulation of levers that would endanger the train while it is within the limits of the route entered.

2.1.1.4

Sectional route locking

Route locking so arranged that a train, in clearing each section of the route, releases the locking affecting that section.

2.1.1.5

Approach locking

Electric locking effective while a train is approaching a signal that has been set for it to proceed and adapted to prevent manipulation of levers or devices that would endanger that train.

2.1.1.6

Stick locking

8

Electric locking taking effect upon the setting of a signal for a train to proceed, released by a passing train, and adapted to prevent manipulation of levers that would endanger an approaching train.

2.1.1.7

Indication locking

Electric locking adapted to prevent any manipulation of levers that would bring about an unsafe condition in case a signal, switch, or other operated device fails to make a movement corresponding with that of the operating lever; or adapted directly to prevent the operation of one device in case another device, to be operated first, fails to make the required movement.

2.1.1.8

Check locking or traffic locking

Electric locking that enforces cooperation between the Operators at two adjacent plants in such a manner that prevents opposing signals governing the same track from being set to proceed at the same time. In addition, after a signal has been cleared and accepted by a train, check locking prevents an opposing signal at the adjacent interlocking plant from being cleared until the train has passed through that plant.

2.2 Track Circuits Track circuits are electrical circuits that are formed including the running rails. They are set up in such a way that when a train is on the tracks that are part of the track circuit, the circuit is altered in some way (usually, by current that normally flows in the track circuit being shunted through the conductive body of the train), thereby activating a detector which may then be used, e.g., to set signals at danger for the section.

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Fig-2.5:Tracking Circiut Track circuits help with interlocked operation as they allow signals to be pulled off only if the section of track they control is safely clear of any vehicles. They also remove the human element of needing to scrutinize the track for the presence of trains that may be out of view of the signalling staff or cabin men. Each circuit detects a defined section of track, such as a block. These sections are separated by insulated joints, usually in both rails. To prevent one circuit from falsely powering another in the event of insulation failure, the electrical polarity is usually reversed from section to section. Circuits are powered at low voltages (1.5 to 12 V DC) to protect against line power failures.

2.3 PRINCIPLES OF TRAIN WORKING All over the world Railway transportation is increasingly used, as this mode of transport is more energy efficient and environmentally friendly than road transportation. Trains move on steel rail tracks and wheels of the railway vehicle are also flanged Steel wheels. Hence least friction occurs at the point of contact between the track & wheels. 2.3.1

Need of Signalling:

There are basically two purposes achieved by railway signalling. 1 To safety receive and despatch trains at a station.

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2 To control the movements of trains from one station to another after ensuring that the track on which this train will move to reach the next station is free from movement of another train either in the same or opposite direction. This Control is called block working. Preventing the movement from opposite direction is necessary in single line track as movements in both directions will be on the same track. 2.3.2

The essential components of railway signalling:

The fixed signals provided by the side of the railway track with indication in the form of colour lights are the actual authority to a driver to get in to the portion of the track beyond the signal. At stations the trains may be received on any one of the platform lines. To take the train to any specific track, points are provided.

2.4 BASIC TRACK STRUCTURE: Trains run on dedicated line .A line consists of two rails running parallel to each other.

Fig-2.6:Basic Track Sturcture This is also called Track. The width of the track is 5‟6”in Broad gauge (B.G) In station yards there will be more than one track for receiving and dispatching trains. Points are provided to divert the running trains from one track to another. The points have movable switches which can be operated electrically by a point machine.

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Fig-2.7: Track With Point Machine

2.4.1

Clearance of track:

Since a train cannot be received on the portion of track where another train is standing on same portion of the track, the signal before it is cleared for the movement of a train has to ensure the track clearance. There are equipments used in Railway signaling to achieve the above safety condition.

2.5 SIGNALS Signal is a medium to convey a particular pre-determined meaning in non-verbal form.

2.5.1

Multiple Aspect Color Light Signal (MACLS):

Multiple means more than 2 indications .They may have 3 or 4 different aspects or indications to be given to the driver. These signals have longer range of visibility and Improved reliability.

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2.5.2

Classification of CLS:

Fig-2.8 Classification of CLS 2.5.2.1 Manual Stop Signal : Each aspect of the signal is represented by a circle. A horizontal line inside the circle indicates Red aspect, an inclined line the yellow aspect and vertical line the Green aspect. The normal aspect of the signal is shown by double line.

Green Yellow Red

Fig-2.9:Manual Stop Signal

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Table-1.1: Manual Stop Signal 2.5.2.2

Permissive Signal (Distant Signal) :

Shall be located at an adequate distance in rear of the stop signal, the aspect of which it pre- warns. The normal aspect of permissive signal is Single Yellow where 2 distant signals are provided to pre- warn the stop signal, the outer most signal, to be located at an adequate distance from the first stop signal, shall be called the distant signal and the other called the inner distant signal, with the distant capable of displaying attention or proceed aspect only. To distinguish between stop signal and permissive signal ‘P’ marker board (letter in black on white board) is fixed to the permissive signal. 2.5.2.3

Automatic Stop Signal :

The normal aspect of an automatic signal is green and is indicated by the double vertical line, unlike the manual signal where the normal aspect is red and indicated by double horizontal lines.

Fig-2.10:Automatic Sgnal 14

An automatic signal has an ‘A’ marker plate fixed to the signal post to distinguish it as an automatic signal. Letter ‘A’ in black on white circular disc. 2.5.2.4

Semi-automatic Stop Signal :

An illuminated ‘A’ marker distinguishes a semi – automatic signal from a fully automatic signal. Letter ‘A’ against black back ground is illuminated when working as an automatic stop signal and letter ‘A’ extinguished when working as a manual stop signal .

2.5.2.5

Gate Signal :

The Gate stop signal shall be provided with ‘G’ marker. Letter ‘G’ in black on a yellow circular disc. A semi-automatic stop signal interlocked with a level-crossing gate shall be provided with ‘G’ marker disc and an illuminated ‘A’ marker. The ‘A’ marker shall be lit only when the gates are closed and locked against road traffic.

Fig-2.11:Gate Signal 2.5.2.6

Routing Indicator :

Where two are more lines diverge, information is to be given to driver that he is being received on diverge line. Hence route indicators are provided. Route indicators are fixed on the first stop signal and starters. If the route indicator on a signal is not in working order, the relevant signal shall also to be treated as defective signal. 15

Route indicator is denoted as (UG). Route indicator are of three types.: 2.5.2.6.1    2.5.2.6.2   2.5.2.6.3 

Junction type route indicator : Used where the speed is above 15KMPH It is having a provision of indicating six diversions and a straight line. When taken off it shows a row of five white lines. Multi lamp route indicator : Used where the speed is less than 15 KMPH. It can exhibit nine numerals and alphabets. Stencil type route indicator : Normally fixed on starter signal.

2.5.2.7

Subsidiary Signals

Signals are used for reception of trains in to a station and despatch of trains out of station. Signals used for movement of trains within the station section at restricted speed and for special purpose are called Subsidiary signals. In MACL signalling Shunt signals and Calling–on signals come under subsidiary signals.

2.5.2.7.1

Shunt signal:

It is of position light type, The lights shall be white in colour. Shunt signals control shunting movements. A shunt signal may be placed on a post by itself or below a stop signal other than the first stop signal of a station. When a shunt signal is taken „OFF ‟, it authorizes the driver to draw ahead with caution for shunting purposes although stop signal, if any, above it is at ‘ON’. When a shunt signal is placed below a stop signal, it shall show no light in the ‘ON’ position.

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2.5.2.7.2

Calling-on signal:

A Calling-on signal has no independent location and displays no aspect in ‘ON’ position. A calling-on signal where provided, shall be fixed below a stop signal governing the approach of a train with ‘C’ marker board fixed to the signal post. A calling-on signal when taken ‘OFF’ it displays a miniature yellow light. Under approved special instructions, a calling-on signal may be provided below any other stop signal except the last stop signal.

Fig-2.12: Calling on Signal When placed below a stop signal, it shall show no light in the ‘ON’ position. A calling-on signal under main signal above it cannot display ‘OFF’ aspect at same time.

2.6 OVERLAP Every stop signal by its indication to the driver controls the movement of train upto the next stop signal as the next stop signal will control the movement beyond it. Hence the track between the stop signal and the next has to be clear and the points have to be correctly set and locked before a movement is permitted by it. However due to any unforeseen reasons like with sudden brake inadequacy the driver may not be able to stop at the next stop signal. So an extra safety margin of the track beyond the next stop signal is also to be kept free so that if the train overshoots the next signal, he will be able to bring the train to stop within that margin. This safety margin is called “overlap”. Similarly 17

we have to ensure that when a train moves on the track the other rail vehicles from the adjoining track should not roll down and infringe with the movement. To prevent this “isolation” between adjoining lines is required. Overlaps are referred to as ADEQUATE distance. Overlaps are of two types: 1) Block Over Lap (BOL) 2) Signal Over Lap (SOL) 2.6.1

Block over lap : It is the extra length of track in advance of the FSS (First Stop Signal) of a station, which must be kept clear, before Line clear can be given to the station in rear.

2.6.2

Signal over lap : The length of track in advance of a stop signal of station, which must be kept clear, before the signal next in rear could be taken ‘OFF’.

2.7 ISOLATION The term isolation denotes the condition in which line for a particular movement of a train is separated from all adjoining lines connected to it in such a manner that it cannot be fouled or interfered with by any movement taking place on the adjoining lines.

2.8 SIGNALING PLAN For any station whether a wayside or a junction, the Engineering department prepares a plan depicting all the lines, points, Level Crossings if any, Foot-over Bridge (FOB), Subway if any coming within the station section, Bridges if any, gradient etc. This plan is called as the "P-way Plan". This plan is studied by the Signal Engineers and based on this a Signalling Plan is prepared indicating the following: 

All gradients with in the station limit on either side upto 2.5 Kms.

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

Kilometer and class of level crossing gate within the station limits, whether interlocked

            

or not. Up & Dn direction, Name of important junction and immediate station on either side. Location of signals, with reference to point and level crossing gate. Marking of signals, points and level crossing gates. Inter signal distances and distance between warning boards & signals Type of Block working with adjacent station and location of Block instrument. Type of turnouts. Description of siding. Restriction on dead end sidings. Crank handle details. Details of Axle counters / Track circuits. Signalling Over lap. Holding capacity of all running lines and sidings. Note regarding telephone communication provided between ASM and Level crossing

       

with in and out of station section. Reference to approved engineering plan on which the signalling plan is based. CRS‟s dispensation for deviation from G&SR / SEM, if any. Aspect sequence chart for CLS. Name of the station, Standard of station. Class of station, Centre line with kilometers, North point. Names of the stations with distance on either end of the station. Panel position / SM‟s control, with spare knobs / slides. Detection table.

2.9 ELECTRICAL KEY TRANSMITTER: Electrical key transmitter is used for the purpose of controlling a signal apparatus such as points, LC gates & signals etc by SM by retaining key of the controlled apparatus (which is normally locked) and issuing the same key for releasing the apparatus when required.

2.10 RELAYS Relay is an electromagnetic device which is used to convey message electrically from one circuit to another circuit through a set of contacts (back or front contacts) and works on the principle of electromagnetism. 19

2.11 TRACK CIRCUITS Track circuit is a vehicle detection device in which the running rails form part of an electrical circuit. The boundaries of track circuit are marked by insulation joints on the rail and rails are bonded at rail joints for better conductivity.

Uses of Track Circuits: 

For detecting the presence of vehicles or absence of vehicles within the limits of the

 

track circuits. For locking the point when train is on the point. Trolley protection circuit for axle counter to ensure wheels of easily removable trolleys are not counted.

2.11.1 Closed Track Circuit : In this type current is always flowing through the relay. When train comes over the track, the supply to the relay is shunted and the relay de-energizes. The smallest closed track circuit provided is of 26 meter length. The longest workable track circuit depends on the Ballast Resistance (i.e., Resistance across rails offered by the stone chips placed below the rail to support track), This ballast decides the leakage current. In other words ballast resistance appears across or in parallel with relay coil resistance.

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2.11.2 Open Track Circuit: Open track circuit is one in which the track relay is normally de-energized and picks up only when train comes on the track. In this track circuit any disconnection with train on the track will drop the relay and failure on unsafe side will take place, as the relay will show track is clear under occupation. Hence this track circuit can be used for short length only i.e., 26 Mts. Now a days open track circuits are not used.

Fig-2.13:Open Tracking Circuit 2.11.3 Fed over track circuit: It is a sub division of track circuit. This is generally adopted when it is not possible to work a long track due to inability to maintain prescribed parameters like ballast resistance for fail safe working of track circuit.

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Instead of dividing it in to independent track circuits, the first track circuit is fed by the usual battery and relay arrangement. The feed to the second track is taken through the front contact of the track relay which controls the first track and so on. The last track relay can serve to indicate occupancy or clearance of the portions of all track circuits.

Fig-2.14: Fed over tracking Circiut

2.12 ELECTRICAL POINT MACHINE An electrical point machine is an electrically driven motor used for operation of points in railway yards. The rotary motion of the motor is transmitted through the reduction gears and transmission assembly and converted through linear movement of a toothed rack through a pinion. The gear rack drives switch rails to unlock, change the position from N to R or R to N and lock the switch at the end of the stroke. Sequence of point machine operation:   

Opening of the detection contacts. Unlock the points. Move the points to the desired position 22

 

Lock the points. Close the detection contacts.

2.13 AXLE COUNTER 2.13.1 Comparison with track circuit: 

To detect the presence of vehicle within a prescribed distance is the role of track



circuit. Dropping of track relay is due to shorting of rails by the axles of a vehicle train.

2.13.2 Features of Axle counter:

It works on magnetic flux variation on a ground device for counting the axles and electronic circuits to evaluate in-count and out-count. To detect the presence of wheel.

2.14 INTERLOCKING Means an arrangement of signals , points and other appliances, operated from a pane or from lever frame, so interconnected by mechanical locking or electrical locking or both that their operation must take place in proper sequence to ensure safety.

2.14.1 Electrical Lockings 2.14.1.1

Route locking:

After a route is set (that is, the points in the route are operated to the position as required for the route), it is electrically locked before the signal is cleared. By this we mean the points in the route are electrically locked and they cannot be operated for any other route till such time the route that is locked is released and the points become free for operation.

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2.14.1.2

Route molding:

Once a route is set, locked and the signal is cleared for a train, it must be held till such time the train is received on the berthing track or the route is released by an emergency route release operation.

2.14.1.3

Track locking:

It is an electrical locking on a point which prevents the operation of the point when a train occupies the track circuit provided over the point. When a train is on 51 AT or 51BT, the respective track relay will be de-energized. Under this condition, it is not possible to operate the point either by route initiation or by individual operation. We say the point is track locked. 2.14.1.4

Indication locking:

It is an electrical locking so provided as to ensure that after the reception of the train on the berthing track the route is not released unless it is proved that the signal which was cleared for receiving the train has gone back to danger and all the signal control relays have de-energized. 2.14.1.5

Approach locking:

It is an electrical locking effective while a train is approaching a cleared signal and adopted to prevent releasing of the route when the train is within a “Pre-determined distance” from the signal.

Fig-2.15: Approach Locking For the purpose of providing approach locking on the signal, a track circuit called “Approach Track” (AT) needs to be provided to a length of 1-2 kms 24

2.14.1.6

Dead approach locking:

It is seen that for providing approach locking, a track circuit for a length of 1,2kms. Need to be provided. Provision of such a long track circuit for the purpose of approach locking is a costly proposition. Therefore, the approach locking is provided without the approach locking becomes effective the moment the signal is cleared irrespective of the position of the train in the approach. 2.14.1.7

Back locking or route locking:

It is an electrical locking effective when a train has passed the signal and adopted to prevent releasing of the route while the train is “within the limits of the route entered”.

2.14.2 Relay based Interlocking Relay Interlocking is a system of implementing principles of interlocking for safe train operations at a Station with the help of electrical circuits wired through electro-magnetic relay contacts and coils. Parts of Sub-Systems of a Relay based Interlocking: 2.14.2.1

Indication-cum Operation Panel:

This panel shows the miniature lay out of the yard with controlling knobs/buttons for operating various functions mounted on the panel. This also gives indications about the status of the functions i.e., Points, Signals, Routes, Gate Control, Track Circuits, etc. This panel is operated by the Station Master who is in-charge of the Train Operations at that Station.

2.14.2.2

Relay Room :

This consists of racks which are wired and on which the relays are mounted. This is the interlocking Centre of the Station. This relay room on one side is connected to the panel

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to receive commands from the panel for operation of the functions and also to give indication to the panel to show the status of the functions which are controlled by the interlocking. On the other side, this relay interlocking takes inputs from the field like position of signals, points, track circuits, etc., and gives output to outdoor functions to drive them. 2.14.2.3

Power Supply Room :

This consists of Power Supply units as under:    

Batteries Battery Charges Voltage Stabilizers Transformers for Stepping down the voltages

2.14.2.4

Power Panel :

This is for connecting the different sources of power i.e., Traction, Commercial Supply, Generator Supply, etc. 2.14.2.5

Outdoor Cable Terminations :

Since controls originate from relay room and go to the outside functions like Points & Signals and their status are repeated to relay room, signalling cables are laid from the Relay Room to the functions. 2.14.3 Two-Hand Operations 1. To ensure that any Signalling gear is operated only by an authorized person, the panel has got a locking arrangement. The key is with the ASM on Duty. When he leaves the panel, he has to lock the panel and take the key with him. Once the key is out, no function can be disturbed by any outsider. 2. To ensure that only a deliberate action by the ASM operates a signal or a point and no inadvertent placing of hand on any button will lead to the operation of the function, the operation of the panel requires both the hands. In other words in the Push Button system where an accidental placing of one hand can operate the button for any 26

function, i.e., signal or point, two buttons are to be pressed. The buttons are so placed that with a single hand, the two buttons will not be pressed. 2.15 SELECTION TABLE The various safety aspects such as interlocking of conflicting routes, requirements of points for each route, the track circuit controls for the points, the route holding requirements such as approach locking and back or route locking and other controls such as crank handle controls, gate controls, block control and overlap release etc. are first put in a table called “control table.” Or “selection table” and this table is used in the preparation of circuits. In the preparation of the control table, the following points should be kept in view: When a route is set and locked, it should lock all other conflicting route may be. A. Directly conflicting route: Route which require all its points in the same position as that of the route which is set and locked. B. Indirectly conflicting route: Route which require at least one of its points in a different setting from the points of the route which is set and locked. 2.16 Points control table The route wise control table does not show the points controlled. Each point is controlled by the point track circuits for track locking so that if any train is moving over the points, the track locking will be effective and the points cannot be operated under the wheels. This aspect is illustrated separately in a points controlled table.

2.17 EXPLANATION OF CIRCUITS 2.17.1 Button relay circuits We have studied in Chapter No.7, the various features provided in the “Control cum Indication Panel”. Every main and shunt signal has a button provided at the foot of the 27

signal symbol on the panel. The route buttons are provided in the middle of the track configuration for each route. These buttons are also known as exit buttons or destinations buttons. Point buttons are provided at the point configuration. The various common buttons such as WWN, EWN, EGGN etc. are fixed on the top of the panel. All these buttons are differently colored for easy distinction. The various buttons are grouped as follows and the button relay circuits are provided accordingly: 

Signal button relays

  

Route button relays Point button relays Common button relays

2.17.2 Common button relay circuit: The following common buttons for the entire station are grouped in this circuit.

1 2 3 4 5 6

CO GGN - Calling on signal button EUYN - Emergency Route Release button. RRBUN - Super Emergency Route Release Button GRN - Common (General) Slot Return button. GBN - Common (General) Slot button EOVN - Emergency overlap Release button.

2.17.3 Route Selection: The energisation of GNR & UNR energizes the route selection relay (LR), provided that no conflicting route is set. Thus the basic interlocking is ensured at this first stage itself. 1 LR is designated after the signal number & with route alphabet, if the signal has

2

more than one route. LR is normally down & picks up when an operation to clear a signal is performed

3 4 5

& when the interlocking permits. LR picks up only when the conflicting LR‟s are not energized. Energization of LR operates the points to the desired position.. LR front contact is used in route checking (UCR) & signal control (HR) circuits.

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2.17.4 Point Operation A point can be operated from normal to reverse or vice versa, as per requirement by any one of the following methods: 1. As a part of route setting for a signal that needs to be cleared. 2. Individual operation of point under normal condition (i.e., Track Circuit Controlling the point is energized). 3. Individual operation of point when track circuit has failed to energize.

2.17.5 Route Checking Relay – UCR 

The route checking relay (UCR) checks that all the points involved in the selected route are correctly set and locked at the site. It also proves that the route set is for the

 

signal route initiated including isolation and overlap. One signal will have one UCR & will be designated by the signal number. It will have parallel paths depending upon the number of routes to which the signal

  

leads. UCR is normally down. UCR front contact will be proved in HR Ckt. UCR back contact will be proved in ASR ckt.

2.17.6 Track Stick Relay (TSR)  

The TSR is controlled by the track circuit ahead of the signal. Normally, one TSR is provided for each signal controlled by the first track circuit after



the signal. Sometimes, two or three conflicting signals have a common track circuit ahead, a



common TSR is provided for these signals. The TSR is normally energized relay under the control of the first track relay. Once it picks up it is kept energized by a stick feed through its own front contact. 29



Once a train passes the signal and drops the first track relay, the stick feed is cut off and TSR drops. This causes LR, UCR and signal control relays to de energize and prevents



automatic re clearance of the signal. Subsequently, when the train clears the first track, the track relay picks up. TSR picks up proving that the UCR and the signal control relays have dropped and sticks.

2.17.7 Emergency Route Release After the signal is cleared it is required to cancel the route. When the train is approaching the signal, emergency route release is done. This is done in two stages. In the first stage, the signal is cancelled by pressing GN and EGGN. This operation throws the signal to danger immediately. In the second stage the route release is initiated by pressing GN and EUYN. But the route release can take place only after a time delays of 2 minutes to ensure that the train has come to a stop at the foot of the signal. But, if the train has passed the signal before 2 minutes time delay and occupied the track circuits ahead, the back locking on the route will be effective and the route cannot be released unless the train clears all the back locking track circuits and arrives fully on the berthing track. In this case the route is released automatically.

2.17.8 Super Emergency Cancellation of Route After the reception of the train on the berthing track, if any of the back locking track circuits fail and the track relay does not pick up, the ALSR relay cannot energize and the route cannot be released. The points remain locked in the route and other routes over the points cannot be set. The route can be released only after the track circuit. Failure is rectified and the ALSR is energized. This may take considerable time and the train traffic will be held up. To avoid delay to the traffic a provision has been made on the panel to release the route even under the back locking track circuit failure condition. This 30

is an unsafe provision in the sense that the SM may release the route even when the train is actually moving over the back locking track circuits. Once the route is released the points become free and can be operated under the wheels which may cause derailment.

2.17.9 Overlap Locking And Release For locking the overlap points OVSR relay is provided. This is also a normally energized relay like ALSR. When ALSR drops, OVSR also drops and locks the overlap points. This relay can be provided individually for the overlaps. Where 2 or 3 overlaps conflict with one another, a combined OVSR can be provided as only one overlap can be set at a time.

2.17.10

Indications on the panel, Failure alarms and emergency counters:

2.17.10.1 Signal indications: Aspects that are exhibited at each signal are indicated in their respective positions. A flashing indication is given under lamp failure. 2.17.10.2 Track indications: Track strip indications are lit by a white light when a route is set & locked, through the back contact of ALSR. Depending upon the point position, corresponding indication strips are lit. 2.17.10.3 Point indication Point indications are given by means of two white lights one each at the main ends of cross over when normal & two white lights on the cross over when set for reverse When none of the point detections is available either during operation or under failure condition, these indications are made to flash through NWKR & RWKR down contacts.

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2.17.10.4 Failure Indications The various button relays are grouped function wise and a common button normal checking relay for each group as GNCR, UNCR and WNCRT provided. When any button fails or button relay fails the button normal checking relay of that group drops and gives indication of the panel. Similarly for giving indication and alarm for the failure of the common buttons or their relays, a relay called GRXR is energized through the back contacts of these Common button relays. 2.17.10.5 Crank handle Interlocking When the crank handle is inside EKT, key in contact is made. KLNR picks up proving crank handle in. If WLRT, the point is free from any signal locking. If CH1 button and common button GBN are pressed together, CH1ZYR will pick up & hold through its own front contact, as buttons will be released. 2.17.11Level Crossing Interlocking Connected Relays: 

LXLR: This relay picks up by proving all concerned ASR/OVSRs of signals in whose route/overlap the L.C. gate falls are free.(i.e., picked up) and UCRs are de-energized



(i.e., route is not set). LXRR: It proves that the gate is free to be opened for road traffic (i.e., LXLR is up) and gate button LXN and common (group) slot release button GBN are pressed. It proves permission is given from the panel to open the gate. Its repeater at the gate is



LXRPR, the front contact of which gives feed to gate key lock to release it. KNLR: Proves gate key is in. i.e., gate is closed against road traffic, locked and key is kept in the place at gate lodge to transfer control to panel at the station. It is the relay in station, repeating another relay KN_R at gate site. KN_R picks up after key is deposited at site by gate man. 32



LXNR: This relay proves control given to the gate has come back to panel and gate can not be opened. After KNLR picks up, panel operator presses LXN + GRN (Group slot restoration button) and LXNR picks up.

2.18 SYSTEMS OF BLOCK WORKING The entry of train onto the block section is jointly controlled by the entry and exit points of the block section. The driver is authorized to proceed into block section by the signal controlling the entry into the section. This working could be the ABSOLUTE BLOCK system stem or AUTOMATIC BLOCK system.

2.18.1 Essentials of Absolute block : Where trains are worked on absolute block system a) No train shall be allowed to leave a block station unless Line clear has been received from the block station in advance, and b) On double lines, such line clear shall not be given unless the line is clear not only upto the first stop signal at the block station at which such line clear is given but also for an adequate distance beyond it . c) On single, such shall not be given unless the line is clear of trains running in the same direction not only upto the first stop signal at the block station at which such line clear is given but also for an adequate distance beyond it, and is clear of trains running in the direction towards the block section to which such line clear is given. The adequate distance referred shall not be less than 180 Mts d) The whole of the last preceding train has arrived complete; and all necessary signals have been put back to „ON‟ behind the said train.

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e) Fig-2.16: System Of Blocking Working 2.19 AUDIO FREQ. TRACKING CIRCUIT 2.19.1 Introduction Audio frequency (AF) track circuits are used for both train detection and cab signal application. AF track circuits utilize a unique carrier frequency between 2 kHz and 5 kHz for train detection for each track circuit which is coded on and off by a low frequency code rate between 2 Hz and 21.5 Hz. Furthermore, a unique carrier frequency for train cab signal transmission is coded on and off in the 3 Hz to 21.5 Hz range. These cab signal carrier frequencies vary throughout the transit property. The actual cab signal speed command transmitted to the train is determined by six different code rates.

Fig.-2.17: AUDIO FREQ. TRACKING CIRCUIT AF track circuits have the unique advantage of eliminating insulated rail joints at track circuit boundaries, except at interlocking boundaries, and using both running rails for negative propulsion return. 2.19.2 Operation AFTC works on the basic principle of short circuiting of two rail signals to detects the train. The ATFC contain a transmitter, a receiver, two TMUs to detect the train. There is one-one TMU are present on transmitter and receiver. Transmitter generate the frequency signal to send to towards the Receiver through rails. The Timing and Matching units are used to select desired frequency. The current from 34

transmitter to receiver is continuously flows in condition of there is no train. Whenever a train approaches on the rails where AFTC is installed because of train the flow of current breaks because of short circuiting and the train is detected. 2.19.3 Specification  Transmitter O/P in Vrm=22 Vac to 58 Vac  Transmiter Current O/P= 150 mA to 300 mA  Transmitter TMU Voltage= 100 mVac to 110 mVac  Receiver TMU Voltage= 100 mVac to 110 mVac  TMU Frequency – 1700hz,2000hz,2300hz,2600hz  Voltage Across AFTC relay= 28.62 (DC) 2.20 TRAIN PROTECTION WARNING SYSTEM 2.20.1 Introduction In spite of the installation of AWS over most of the railways main line , there has been a gradual increase in the number of signals passed at danger (SPADs) in recent years and some serious collisions as a result.

In an attempt to reduce these, a number of

suggestions were made to reduce the impact (pun intended) of SPADs. One of these is the Train Protection and Warning System or TPWS.

The idea behind TPWS is that, if a train approaches a stop signal showing a danger aspect at too high a speed to enable it to stop at the signal, it will be forced to stop, regardless of any action (or inaction) by the driver. The equipment is arranged as shown left. For each signal equipped with TPWS, two pairs of electronic loops are placed between the rails, one pair at the signal itself, the other pair some 200 to 450 metres on the approach side of the signal. Each pair consists of, first an arming loop and secondly, a trigger loop. The loops are activated if the signal is showing a stop aspect. The pair of approach loops first met by the train at 400 to 200 metres before the signal, are set between 4 and 36 metres apart. When the train passes over the arming loop, an on-board timer is switched on to detect the elapsed time while the train passes the

35

Fig-2.18: Train Protecion Warning System distance between the arming loop and the trigger loop. This time period provides a speed test. If the test indicates the train is travelling too fast, a full brake application will be initiated. In case the train passes the speed test successfully at the first pair of loops but then fails to stop at the signal, the second set of loops at the signal will cause a brake application. In this case, both loops are together (see photo - right) so that, if a train passes over them, the time elapsed will be so short that the brake application will be initiated at any speed.

Fig-2.19Working of TPWS 2.20.2 Operation TPWS has certain features which allow it to provide an additional level of safety over the existing AWS system but it has certain limitations and does not provide the absolute safety 36

of a full Automatic Train Protection (ATP) system. What TPWS does is reduce the speed at which a train approaches a stop signal if the driver fails to get the speed of the train under control to allow him to stop at the signal. If the approach speed is too fast, TPWS will apply a full brake but the train may still overrun the signal. Fortunately, since the train is already braking and there is usually a "cushion" of 200 yards (183 metres) between the signal and the block it is protecting, there will be a much reduced risk of damage (human and property wise) if the train hits anything. With a possible total distance of 2000 feet (about 600 m) between the brake initiation and the block entrance, trains "hitting" the first loops at up to 120 km/h (75mph) could be stopped safely. TPWS is also provided at many (about 3000) Permanent Speed Restrictions (PSRs) to ensure that a train does not pass through a restricted section of line (say one with a sharp curve) at too high a speed. However, there have been a number of issues related to the use of TPWS in these cases. Drivers have complained that, although they were approaching the PSR at a speed which would allow the train to run at the correct speed within the restriction, they still got stopped by the TPWS "speed trap". This has led to some vigorus discussions between Network Rail, the train operating companies and the HSE. An add-on to TPWS, called TPWS+ is provided at certain signals where train speeds are above 100 mph or 160km/h. The safety effects of TPWS are limited by the fact that it is provided only for stop signals and that it cannot have any effect at caution signals. This means that there is a range of speeds at the higher level which will be excluded from full protection. In spite of this, it is suggested in published data that 60% of accidents due to SPADs will be prevented by the installation of TPWS at critical locations. This is achieved, it is said, at 10% of the installation costs of a full ATP system. TPWS does not replace the existing AWS system. AWS is retained, so the driver will still get the warnings advising him of adverse signals. The TPWS equipment is designed to interface with the existing on-board wiring of trains so that it can be fitted quickly.

37

2.20.3 Parts of TPWS 2.20.3.1 BALISE A balise is an electronic beacon or transponder placed between the rails of a railway as part of an Automatic Train Protection (ATP) system. The French word "balise" is used to distinguish these beacons from other kinds of beacon. A balise typically needs no power source. In response to radio frequency energy broadcast by a Balise Transmission Module mounted under a passing train, the balise either transmits information to the train ('Uplink') or receives information from the train ('Downlink,' although this function is rarely used). The transmission rate is sufficient for a complete 'telegram' to be received by a train passing at any speed up to 500 km/h. A balise may be either a 'Fixed Data Balise,' or 'Fixed Balise' for short, transmitting the same data to every train, or a 'Transparent Data Balise' which transmits variable data, also called a 'Switchable' or 'Controllable Balise'. (Note that the word 'fixed' refers to the information transmitted by the balise, not to its physical location. All balises are immobile).

38

Fig-2.20: Balise A fixed balise is programmed to transmit the same data to every train. Information transmitted by a fixed balise typically includes: the location of the balise; the geometry of the line, such as curves and gradients; and any speed restrictions. The programming is performed using a wireless programming device. Thus a fixed balise can notify a train of its exact location, and the distance to the next signal, and can warn of any speed restrictions. A controllable balise is connected to a Line side Electronics Unit (LEU), which transmits dynamic data to the train, such as signal indications. Balises forming part of an ETCS Level 1 signalling system

employ this capability. The LEU integrates with the

39

conventional (national) signal system either by connecting to the line side railway signal or to the signalling control tower. Balises must be deployed in pairs so that the train can distinguish the direction of travel 1→2 from direction 2→1, unless they are linked to a previous balise group in which case they can contain only one (1) balise. Extra balises (up to 8 per group) can be installed if the volume of data is too great. Balises operate with equipment on the train to provide a system that enhances the safety of train operation: at the approaches to stations with multiple platforms fixed balises may be deployed, as a more accurate supplement to GPS, to enable safe operation of automatic selective door opening. 2.20.3.2 BTM TPWS (Train Protection and Warning System), term used by Indian Railways, It applies to the ETCS Level 1 concepts and the UIC/UNISIG specifications. It does not, in Indian terms, apply to the UK implementation that is based on different technology. The TPWS project on Southern Railway installed in the Chennai Central/ Chennai Beach – Gummidipundi section of Chennai division was commissioned on 2nd May 2008 on 4 EMU rakes to begin with. The works on the balance 37 rakes were progressively completed in the next few months. Presently all the 41 rakes proposed to be provided with TPWS on-board equipments are functional. The TPWS track side equipments in the section were fully provided, commissioned and made functional right from the date of commissioning.

40

Fig-2.21:BTM Table:2.2:BTM System Problems:

41

This TPWS project based on the European Train Control System (ETCS) Level-I system faced many hurdles during the initial installation, proto-type testing, obtaining the required clearances from RDSO and CRS. The major problems noticed during initial revenue service included 1. On-Board system not booting. 2. On-Board system going into System failure (SF) during booting. 3. SDMI ( Simplified Driver Machine Interface) going blank. 4. Speed display bouncing on the SDMI leading to braking. 5. Brake application in the rear non-driving motor coach on run. Corrective Actions Taken by Railways: 2.21.3.1 Intermittent BTM failure: Analysis revealed that there was antenna impedance mismatch. The standing wave ratio (SWR) was found more than the tolerance limit of 1.2 to 1.4. Interference from EMI was also suspected. There was problem in communication between the onboard computer (OBC) and BTM. The corrective actions for these problems included modifying the existing antenna protection cover and providing copper braided shields for the Tx-Rx cable between antenna and BTM and for the COTDL and PROFIBUS cable between OBC and BTM. The BTM configuration files were also modified based on some internal parameters.

2.21.3.2 Error in Train Interface Unit: Analysis revealed that there was problem in communication between some modules of the OBC and now screened twisted pair cables have been introduced to protect the signals from external noise and EMI. 2.21.3.3 Error in Speed Sensor: To improve the performance of the Odometric system, the signal cables between OBC and speed sensors have been provided with copper braided shield firmly connected to the coach body. To suppress the noise in the 110V DC voltage derived from the motor coach battery, a filter has been provided at the input point of the OBC. The traction control relay has been shifted outside the OBC cubicle to reduce EMI. To improve earthing of the 42

motor coach body, a 50 sq mm copper cable is to be connected between the EMU body and its bogie. 2.21.3.4 Back EMF from the EB & EP relay coils: To cover come this problem, the relay coils and EB valve solenoid coils to be terminated with 180/200V MOVRs and the body of EB & SB relays to be firmly connected to the coach body. 2.21.3.5 EB application in rear coach:To overcome the problem of application of EB in the rear coach while running, the brake interface circuit has been modified to bypass the EB when the TPWS system in the sleeping mode (SM) i.e., when the cab is not the driving one. 2.21.3.6 SDMI Blanking:To overcome the problem of SDMI blanking, its software has been upgraded. Apart from this, the OBC-SDMI communication cable connector cover which was earlier plastic has been changed to metallic. The OBC-SDMI communication cable and the SDMI power supply cable have been shielded with copper braids firmly connected to the coach body. A filter has been provided at the 110 VDC input point of the SDMI to suppress the ripples in the power supply.

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CHAPTER- 3 TRAINING WORK 3.1 MICROLOK II SYSTEM 3.1.1

Introduction

Microlok II interlocking control system is a multi-purpose monitoring and control system which is designed for rail mass transit wayside interlocking functions such as switch machine and signal lamp control, track circuit occupancy monitoring and non vital code line communications.

The Microlok II system provides control and monitoring functions for all elements of basic railway vital interlocking. Supervision and control of switch machines, switch locks, signal lamps, searchlight signal mechanisms, and line wire communication circuits are managed by the vital microprocessor on the system card file CPU board. Standard vital output boards interface discrete commands from the CPU board to switch machine relays or other types of vital relays as required. Non-vital bi-polar output boards interface CPU commands to searchlight signal mechanisms and any other equipment requiring a non-vital bi-polar voltage output. Vital lamp driver boards enable direct lighting of color light and searchlight signal lamps. Vital input boards interface various external circuit inputs back to the CPU board. Typical vital inputs include searchlight mechanism position, switch machine correspondence, and interlocking OS track circuit occupancies. The Microlok II system is also capable of interfacing with coded track circuits adjacent to the controlled interlocking.

The devices included with the system that divide the basic Microlok II interlocking control function include a vital cut-off relay (VCOR) and an isolation module. The VCOR 44

relay is controlled by the card file vital outputs such as switch machines and signal lamps. The microprocessor responds to the failure of a safety critical diagnostics by commanding the card file power supply board to remove the dc supply to VCOR coil. The isolation module provides the equivalent of double break protection of the circuit when the system is controlling vital relays or interfacing with line circuits in a separate equipment house. The isolation module is also capable of converting a unipolar output to a bi-polar output.

The main applications and functions of the Microlok II system include the direct control of wayside signals in which the color light signals and search light signal mechanisms are handled and are controlled. Apart from these there are many other applications which involve Microlok- II system to play a vital role in signal conditioning and monitoring of the track circuits.

3.1.2

System Components

The Microlok II interlocking control system is a multi-purpose monitoring and control system designed for railroad and rail mass transit wayside interlocking functions such as switch machine and signal lamp control, track circuit occupancy monitoring, and nonvital code line communications. The Components Listed Below: o o o o o o o o o

The system card file CPU PCB board Vital inputs and output PCB Non-vital I/O PCB Power supply PCB VCOR Relay Address Select PCB EEPROM PCB Terminals 45

o Surge Suppressor 3.1.3

Serial Communication Circuits

The serial communications Circuits is used in Microlok II applications that require a vital serial data link between systems in different equipment houses or cases. This protects the serial channels from voltage transients. A single, standoff-mounted printed circuit board on the panel contains the EIA/current loop conversion circuitry. User devices include a power on/off switch, a fuse assembly, power status lamps, and communications status lamps for the current loop half of the interface. The list of Serial Comm. Components as below: o o o o o o

RS Serial Server/Switches Fiber Optical Cable Serial to Ethernet Converter Optical Fiber Modem Isolator & Converter RS-232,RS-432,RS-485

3.2 SYSTEM COMPONENTS 3.2.1

System Card File

The Microlok II system card file contains the system’s central controlling logic and circuits that interface this logic directly to external circuits or intermediate units (Microlok II track interface panels, for example). Logic and interface circuits are contained on the familiar Euro card format plug-in printed circuit boards. The system card file contains 20 card slots, although not all slots will be used in every application. Each installed circuit board plugs into a common backplane motherboard. The backplane distributes circuit board operating power and enables the CPU board to control and monitor other boards in the card file.

46

The specific circuit boards used in each Microlok II system are determined entirely by the system application, although typical configurations are recommended to optimize available card file space. No particular slot is restricted to a particular board, however the code system interface printed circuit board (when used) is typically placed in the far right slot (slot 20) because of its non-standard front panel width. In addition, the board configuration must agree with the configuration defined in the application logic software. To prevent accidental insertion of a board in the wrong card file slot, each board is equipped with male keying pins. These pins correspond with keying plugs installed in the associated backplane slot connector. The keying pins are installed in the field once the board configuration is determined. Several other restrictions are placed on the installation of the non-vital I/O printed circuit boards and the local control panel. Refer to service manual SM-6800B for specific board installation rules. In order to allow communications between the CPU board and the other boards in the card file, each board must have its bus address configured in hardware. This is accomplished by means of a set of six two-position jumpers, mounted at the rear of the card file in the external cable/connector housing attached to the top connector of each board. Jumper settings are defined in the application software. Not all Microlok system card file boards communicate directly with the CPU board through the card file backplane. Certain boards interface to other board which, in turn, communicates with the CPU.

47

Fig-3.1: Card File

3.2.2.1

Split Card File:

The split backplane allows two independent CPU and associated circuit boards to be housed in a single card file, certain Microlok II applications require that redundant systems be provided. In order to accommodate this requirement a split backplane is needed. This split backplane has been made from a 19-slot mother board. An additional power connector is placed on the split side in the space formerly occupied by slot-2. This reduced the slot count to 18. The copper is separated at the center between slot-10 and slot- 11 with all traces power and ground planes severed. A brief schematic of the split card-file is shown in the figure. As discussed above it consists of two CPU slots and similarly twin slots for other printed circuit boards. It is a special type of card file which can perform multiple operations at once. 48

3.2.2 CPU Board The CPU board contains the central controlling logic and diagnostic monitoring for the Microlok II system, and provides serial five data ports. Four of these ports are used for communication with external systems. The fifth port enables the connection of a laptop PC for software maintenance, diagnostics, and data log downloading. This diagnostic port is terminated at the 9-pin connector on the CPU board front panel The four general purpose ports can be used for vital serial communications with another Microlok II system, a Microlok system, or one of the MicroTrax systems (coded track, end-of-siding or cab signal controller). For installations where the Microlok II system is communicating with another vital system in the same house or case, the maximum serial cable length is 50 ft. A modem is required for cables longer than 50 ft.

The Standard MicroLok II CPU PCB performs a variety of functions such as: o Monitoring external indications from vital input PCBs and non-vital input PCBs. o Processing vital external indications and executing logic defined in the Application logic. o Driving vital output PCBs as required by the Application logic. o Monitoring and controlling serial communication ports (which are links to other controllers). The four general purpose ports can be used for vital serial communications with another Microlok II system, a Microlok system, or one of the MicroTrax systems (coded track, end-of-siding or cab signal controller).

49

Fig-3.3:CPU Front panel

50

Fig-3.4:CPU Board

3.2.3

Vital Input Board

51

Table:3.1:Vital Input Board Each of the vital input PCBs can accept up to 16 isolated inputs. The specifications for these boards are as follows:

Fig-3.5:Vitual Input Bard

52

There are no power connections required through the upper connector. When wiring a vital input PCB to a relay contact circuit contained in the same house as the Microlok II card file, the signal battery may be used as the energy source to activate the inputs. Terminals designated (-) may be connected to battery N12 and B12 switched over relay contacts. When wiring a vital input PCB to a relay contact circuit outside the Microlok II house, use the isolated source that is part of the power supply. This is consistent with the practice of confining signal battery to the case in which the Microlok II unit is housed. External wiring should be protected with equalizer lightning arrestors from line-to-line (US&S part number N451552-0101) and with high voltage arrestors from line-to-ground (US&S part number N451552-0201).

SPECIFICATIONS: (VIAL I/P)

 

Each Vital Output PCB is having 16 inputs. Each vital input is assigned to the detection of outdoor gear status such as ECRs in case of signal, WKR in case of points and TPR in case of Track.



Since the inputs are dealing with the detection of outdoor gears they normally configured with double cutting arrangement.

3.2.4

Vital Output Board

Table-3.2:Vital Outbut Board 53

Each of the standard vital output PCBs provides up to 16 outputs. The specifications for these boards are as follows:

Outputs are controlled by “high side” software-controlled switches. Loads should be connected from outputs to battery negative. The high side switch is used to connect battery (+) to the output. Each output is protected with a polyswitch, which acts like a circuit breaker. When the over current trip point is reached (approximately 0.75A), the polyswitch switches to a high impedance. The switch resets to its normal low impedance when the additional load or short is removed. A short to battery (-) will trip the polyswitch and cause the VCOR relay to drop, but will not cause any damage. A short to battery (+) will not cause any damage, but since this condition is equivalent to a false output, the Microlok II CPU will cause the VCOR relay to drop.

SPECIFICATIONS: (VIAL O/P) 

Each Vital Output PCB is having 16 independent 24 V outputs.



Each output is assigned to the final relay which is driving the outdoor signalling



Gears such as HR, DR in case of signal & WNR, WRR in case of points.



Since the output boards are driving outdoor gears, they are continuously monitored by the CPU and any abnormal voltage present in the output will lead to



System reset / shutdown to ensure safety.

3.2.5

Non-Vital I/O Board

Two versions of the non-vital NV.IN32.OUT32, I/O PCBs are available. The LCP version (N17000601) is designed for use with the optional Microlok II Local Control Panel (LCP) 54

– N16901301. This version of the board is fitted with a 48-pin connector on the front and back. The front connector engages the LCP. The remaining I/O (16 inputs and 8 outputs) are available on the rear connector. The other version of the NV.IN32.OUT32 board (N17061501) connects each of it’s 32 inputs and outputs to a 96-pin connector mounted on the rear of the board. Both boards are treated as the same type of board in the Microlok II application software. The NV.OUT32 PCB provides 32 isolated, outputs for control of external devices such as indicators and relays. The outputs are divided into two groups of 8 outputs and one group of 16 outputs, each group having a separate bussed common (negative DC) reference output. Isolation allows switching power from sources isolated from the Microlok II power supply battery. Outputs are designed to operate at battery voltages between 9.5 and 35VDC. Outputs switch positive battery and are capable of supplying up to .5AMPS. Nominal voltage drop per output is load dependent and usually less than 2.5volts. The NV.IN32 PCB provides 32 isolated external inputs. The 32 inputs are divided into two groups of 8 inputs and one group of 16 inputs, each group having a separate bussed common (negative DC) reference input. External input voltages between 6 and 35VDC represent logical “1”.

55

Fig-3.6:Non-Vital I/P Boards

56

Advantages:

 Allow MicroLok II systems to interface most types of non-vital external devices and circuits.  Ample number of I/O channels meets most application needs.  Isolated (house-external circuit) and non-isolated (house-internal circuit) versions available.  Separate LEDs show states of all channels, including 32-channel versions.  Bi-Polar version available for bi-polar driver circuits (e.g. searchlight mechanisms)  All boards service-proven on railroad and transit properties.

3.2.6 Power Supply The N16600301 power supply board provides two regulated output voltages that are needed for the operation of the card file circuitry. The power supply board performs the following functions:

  

Converts the external supply voltage (9.8 to 16.2 Vdc) to regulate +12V and +5 for outputs to the system card file internal circuits. Provides an isolated source voltage for external contact sensing. Supplies energy to the VCOR relay coil under the control of the CPU printed circuit board.

The power supply board serves a vital role in the fail-safe design of the Microlok II system. The Microlok II CPU board outputs a 250 Hz check signal to the power supply board as long as the diagnostic checks performed continuously by the CPU detect no internal or external system faults. Failure of a diagnostic check results in the removal of the check signal from the power supply board. The power supply board responds by 57

removing the hold voltage from the VCOR relay coil (400Ω). This, in turn, results in removal of power to all vital system outputs. The regulated +12V and +5V power is distributed to all system card file printed circuit boards through the card file backplane bus. Both voltages are used to power board components and circuits. The +12V output of the power supply board is not used as a source for any vital or non-vital outputs. External battery power is used for this purpose. The optional Microlok II power-off relay provides a means of reporting a commercial power failure (serving the battery charger) to the Microlok II system. The output of this relay can be tied to a non-vital or vital input.

Fig-3.7:Power Supply

3.2.7 VCOR Relay(VITAL CUT-OFF RELAY)

58

To ensure maximum operational safety in MicroLok II-based systems, all vital outputs (e.g.to switch machines, signals) are routed through a Vital Cut-Off Relay (VCOR), which is controlled by the system’s vital CPU board logic. The VCOR is a key part of ASTS USA “Inherent Fail Safety” design concept, which ensures that all signaling equipment under MicroLok II control is downgraded to the most restrictive state in the event of a critical fault. The MicroLok II CPU board performs constant internal and external diagnostics and generates a “System OK” check signal as long as diagnostics are satisfactory. While this signal is present, a Power Supply PCB output energizes the VCOR coil and keeps the relay’s power-carrying contacts closed. In this condition, outputs to switch machines, signals, etc. are supplied their required operating power. In the event of a non-recoverable system fault, the CUP sends a command to remove the Power Supply PUB output, thus reenergizing the VCOR coil and cutting off power to the vital outputs. The signaling system is then reverted to the most restrictive state. For applications using the standard MicroLok II card file, the VCOR is typically attached to rack mounting bars and base adjacent to the card file. For applications using the MicroLok Intermediate or End Point card files, the VCOR is contained inside the card file in a separate bay next to the PCBs. These card files are already equipped with a built-in VCOR plug-in mounting base.

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Fig-3.8: VCOR Relay

Each card file will have one Vital Cutoff relay (VCOR) to ensure the healthiness of the system. VCOR has 6 F/B dependent contacts each rated for 3 Amps. 

The VCOR contacts are used to control the power to all card file vital outputs.



The VCOR is controlled by the CUP board.



When the system is healthy the coil receives voltage from PS PCB on the power supply board.



On failure of a safety-critical diagnostic, the DC supply to the VCOR is removed thereby opening the contacts that provide battery power to the vital output boards.

3.2.8 EEPROM PCB EEPROM PCB which is provided on rear side of the CPU connector to configure various serial communication ports. Keying plugs are provided in the card file to ensure coding to each type of cards.

Fig-3.9: EEPROM PCB

EEPROM PCB 60

3.2.9 Address Select PCB  It is wired in every vital and non-vital I/O boards for cpu addressing. The power supply PCB does not have an address select PCB connected to it.  It is installed at rear end of connecter assemblies.  The jumper setting of boards can be found by looking at the configuration menu in MicroLok II maintains tool.  The jumper setting do not depending on the order of boards that happened to appear in the card file. 3.2.10 Terminals Phoenix make terminals are used in MicroLok II wiring. 

One in two out type terminals are used for connection between non-vital I/O boards to

 

panel and vital input board to relay rack and serial communication circuits. Diode type terminals are used for vital o/p board to relay coils. Two in two out type terminals are used for connection between relay rack to cable



termination rack. One in one out type terminals are used for relay coil to supply negative and power

distribution.  Link and fuse terminals are used for power circuit. 3.2.11 Surge Suppressor 230V AC to operator PC and maintenance PC are connected through surge suppressor to protect the equipment from lighting damages. 3.3 SERIAL COMMUNTICATION CIRCIUTS 3.3.1 RS Communication Ports 3.3.1.2 RS-485 Serial Ports Serial ports 1 and 2 are the RS-485 serial ports. Port 1 supports TXD and RTS output signals and RXD, DCD, and CTS input signals. Data clock signals including transmit clock (TXC) which may be either an input or an output and receive clock (RXC) which is an input are present on port 1 but are not currently not supported by the MICROLOK II executive. These signals should not be connected. These signals may be supported in a future release of the MICROLOK II executive. Port 2 supports TXD and RTS output signals and RXD and DCD input signals. 61

Each RS-485 port signal is transported by a twisted pair of wires labeled as XXX- and XXX+ (TXD- and TXD+, for example). Outputs labeled with a (-) always connect to inputs labeled (-) or (A). Outputs labeled with a (+) always connect to inputs labeled (+) or (B). Differential voltage between (-) and (+) conductors of a pair is typically 1.5 to 5 volts with the (-) conductor negative with respect to the (+) conductor when the signal is not asserted. (For data lines TXD and RXD, the quiescent or unasserted state is identified as the MARK state.) In addition, the signal commons (COM) for all ports on an RS-485 communication link must be connected together to equalize potential between signal commons for the connected units. When two MICROLOK II units powered by the same battery are serially connected, the connection of serial commons is made through negative battery and does not have to be made through the serial cable. Note that COM cannot be connected to frame or earth ground as it is directly connected through the MICROLOK II power supply to negative vital battery. RS-485 ports should be interconnected using ONLY twisted pair cable with an over-all shield. For best performance, the interconnecting cables should not contain extra, unused pairs. Any unused pairs should be connected together at both ends of the cable and connected to signal common (COM) for best noise immunity. If connected, the shield should be connected to frame ground at one end of the cable only. On the units at each end of the communication circuit, 120 ohm, ½ watt external load resistors should be placed across the TXD and RTS transmitters and across the RXD and DCD receivers. Any units in-between should simply “bridge” the circuit using a bridging “stub” which is as short as possible. On a multi-drop communication circuit (a circuit to which more than two units are connected), the DCD input on the master unit should be biased in its unasserted state. This may be done by connecting 470 ohm, ½ watt resistors between the DCD- input and 0V and between the DCD+ input and +5V. The load resistor for the master DCD input should be 240 ohms, ½ 62

watt (rather than 120 ohms) to maintain the required circuit impedance for the biased circuit. If the CTS input on any serial port is available but not used, it should be forced to its unasserted state. To permanently force an unused RS-485 input to its unasserted state, the (+) input should be connected to +5V and the (-) input should be connected to COMMON (0V). To force an RS-485 input to its asserted state the (+) input should be connected to COMMON (0V) and the (-) input should be connected to +5V or +12V. 3.3.1.2 RS-423 Serial Ports Serial port 3 is the RS-423 serial port. Serial port 3 supports TXD and RTS output signals and RXD, DCD, and CTS input signals. Data clock signals including transmit clock (TXC) which may be either an input or an output and receive clock (RXC) which is an input are present but are not currently supported by the MICROLOK II executive. These signals should not be connected. These signals may be supported in a future release of the MICROLOK II executive. In an RS-423 interface, outputs are referenced to signal common (COM) while inputs have their own independent common, receive common (RXCOM). Signal outputs are connected to signal inputs by a single wire as the are in the RS-232 interface but COM on each end is connected to RXCOM on the other end. As this connection of commons does not equalize potential between the signal commons (COM) of the two connected units, an additional connection must be made between COM terminals on the connected units. The quiescent or inactive state for all signals is between –3.6 and –6 volts. (For data lines TXD and RXD, the quiescent state is the MARK state.). The active state for all signals is between +3.6 and +6 volts. RS-423 ports should be interconnected using only multiconductor cable with an over-all shield. The cable should not contain any twisted pairs. The serial port commons (COM) should be connected using one of the conductors in the cable (NOT the shield). For best performance, interconnecting cables should not contain extra wires. Extra wires should be connected together and connected to COM at both ends 63

for best noise immunity. Note that COM cannot be connected to frame or earth ground as it is directly connected through the MICROLOK II power supply to negative vital battery. The cable shield should be connected to frame ground at one end of the cable only. If CTS is not used, it must be forced to its unasserted state. To permanently force an input to its unasserted state, the input should be connected to -12V. To force an input to its asserted state, the input should be connected to +12V. RS-423 ports may be connected to RS-232 ports by strapping COM and RXCOM terminals together on the RS-423 end and connecting signals as described under the RS232 connection scheme below. 3.3.1.3 RS-232 Serial Ports Serial port 4 is the RS-232 serial port. Serial port 4 supports TXD and RTS output signals and RXD and DCD input signals. Each RS-232 signal is transported by a single wire and is referenced to signal common (COM). When any RS-232 signal is not asserted the voltage level for that signal is between –3 and –15 volts. (For data lines TXD and RXD, the quiescent or unasserted state is the MARK state.). The asserted state for all signals is between +3 and +15 volts. RS-232 ports should be interconnected using only multiconductor cable with an over-all shield. The cable should not contain any twisted pairs. The serial port signal commons (COM) should be interconnected using one of the conductors in the cable (NOT the shield). For best performance, interconnecting cables should not contain extra wires. Extra wires should be connected together and connected to COM at both ends for best noise immunity. If connected, the cable shield should be connected to frame ground at one end of the cable only. The length of interconnecting cables should be limited to 50 feet or less. If it is necessary to permanently force an input to its unasserted state, the input should be connected to -12V. To force an input to its asserted state, the input should be connected to +12V.

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3.4 MICROLOK II MAINTANANCE TOOLS PROGRAM 3.4.1 Introduction Maintenance personnel and application engineers can perform a wide range of Microlok II system maintenance, configuration and diagnostic functions using the tools provided in this Maintenance tools program. Following tasks can be performed with this program:  Viewing the current status of the Microlok II equipment and related systems.  Reviewing stored system event and error data.  Reconfiguring and resetting the system when necessary. The Maintenance Tools program provides these tools as selections on the Microlok II Maintenance Tools main menu, as shown in fig. The main menu displays the selection buttons that activate the primary functions of the program.  These selection buttons are grouped into four categories:  Run-time Monitor  Historical Data  System adjustment/Setup  Other Tools The Maintenance PC is linked to the Microlok II installation CPU board through an RS232 serial connection. 3.3.1 Powering Up The Microlok II System: o Before applying power to the system for first time, the entire hardware installation should be verified for correctness as per relevant instruction manual.

Fig-3.10: MICROLOK II MAINTANANCE TOOLS PROGRAM 65

o Once the verification is completed satisfactorily, apply +12 V DC battery power to the MicroLok II card file. o Verify that the 5 V ON LED on the card file power supply board is illuminated. If everything has been connected and configured properly, the Microlok II CPU will begin to run a series of self-tests and initialization routines. After successful completion of above procedure, CPU board will assume the on-line mode of operation and the o o o o o o o o

following card file indications should be present: The CPU board ON- LINE LED - ON. The CPU board VPP ON LED - OFF. The CPU RESEST LED – OFF. The CPU upper 4- character display repeatedly scrolls the phrase “US&S MICROLOK II” and the executive version information. The CPU lower 4-character display scrolls the pre-programmed application name. The power supply board VCOR LED – illuminated. If all the above indications are present, perform the System test and configuration procedures as per instruction manual.

3.3.2 Precautions: 3.4.3.1 Electroststic Discharge Precautions: When working on the Electronic Interlocking System, contact with the system printed circuit boards cannot be avoided. Hence following guidelines to be observed:  Always stand on an approved conductive floor mat when touching or handling printed 

circuit boards. Always wear a strap grounding device. The wrist strap should have a 1.0 mega ohm current limiting resistor. Connect the wrist strap grounding connector to suitable



ground connection. Periodically check each wrist strap for continuity using an approved tester. Continuity readings must be between 500 k ohms and 10 megaohms. Discard any wrist strap that

 

does not meet this criterion. Always handle printed circuit boards by the edges. Do not touch board components. Keep the work area clean and free of debris. Avoid using non-conductive materials such as Styrofoam cups, plastic ashtrays, cellophane wrappers, or plastic covered binders in the vicinity of the cards and modules.

66



Once removed from the card file/rack, immediately place printed circuit boards into an anti-static conductive-shielded bag. Wrap the bag in conductive foam to protect the circuit board during transport and shipment. Modules fitted with batteries may require



special packaging. Avoid wearing clothing made of synthetic fabric when handling modules. Cotton

overalls are preferred. 3.4.3.2 Packing: All plug-in modules and cards shall be packaged in anti-static packaging to prevent damage to Electro-Static Sensitive Devices (ESSD) from electro-static discharge. When so packed, the modules may be stored and transported without further precaution. 3.4.3.3 Storage: For storage of Modules and cards following precautions shall be taken:  Must not be in close proximity to magnets, e.g. Automatic Warning System (AWS)   

magnets. Must be protected from damage due to electrostatic discharge. Must be protected from the environment including physical handling damage. If many modules are involved, it is permissible to use conductive card frames or racks. However bags and wraps are preferred.

3.4.3.4 Transport: The equipment or modules must not be transported in close proximity to magnets e.g. AWS- magnets. 3.4.3.5 Handling Lithium Batteries: Following precautions should always be observed while handling Lithium Batteries. 3.4.3.6 Packaging: Package all modules with batteries in a non-conductive anti-static bag. An electrically conductive bag may short the battery terminals causing premature discharge of the battery. 3.4.3.7 Damage: The lithium batteries contain very highly corrosive electrolyte. If a battery is damaged:  Ensure unnecessary personnel do not enter the affected area.  Ventilate the immediate area.  Avoid contact with any liquid or internal components by wearing the appropriate safety 

equipment. Thoroughly wash the affected area with clean water and allow it to dry. 67



Return the module that may have been in contact with the electrolyte to the firm for inspection duly packaged with an appropriate safety warning.

3.5 DO’s AND DON’TS: 3.5.1 DO’S:  To avoid possible damage to the diagnostic computer when connected to the Electronic Interlocking equipment, if the power supply of the diagnostic computer is connected to an AC power source, isolate the power source from earth ground by way of a 3-prong to 2-prong adapter.  Before powering up the Electronic Interlocking equipment, ensure that there is no train entering into the section in both Up and Down Direction.  Observe all Electrostatic discharge precautions while handling any Printed Circuit Board or board component.  For repair or replacement if any, return the equipment to the firm. 3.5.2 DON’TS:  Do not use Radio equipment within the immediate vicinity of Electronic Interlocking system as Radio transmissions can affect electronic equipment.  Do not make circuit alterations or repairs to the Electronic Interlocking system.  Do not install or remove any printed circuit board with battery power applied to the system.  Do not attempt to repair any Electronic Interlocking system printed circuit board or peripheral device in the field. 3.6

Microlok II Development System

The Microlok II development system contains the tools necessary to develop and compile an application logic program, debug the program, and upload the application program to the Microlok II system hardware. The development system also contains the tools required for field installation, system configuration, monitoring, maintenance, and troubleshooting There are three main components of the prototype Microlok II development system:

68



The text editor is used to create the application source file using a predefined file structure. Any DOS or Windows-based text editor application can be used for this



purpose. The logic compiler is a PC-based tool that checks the application source file for errors and then generates the appropriate application file for transfer to the Microlok II CPU board flash EPROMs. The compiler also generates error and program listings, symbol table information, and installation information. This program is a 32-bit Windows 95



application that runs in a DOS window. The Microlok II Maintenance Tools program is a PC-based application that is used to upload an application program to the Microlok II system, configure the Microlok II unit during system commissioning, obtain system status and historical information from the system log, user log, and error log, and debug the application logic by displaying logic states as the program executes. The Tools program is typically loaded on a laptop PC. The PC is in turn connected by an RS-232 serial connection to the Microlok II CPU board diagnostic port. The general process for developing and implementing a Microlok II application is



illustrated in the figure below: An application engineer reviews the planned Microlok II application and identifies specific system requirements such as the Microlok II circuit boards to be used, system



interconnects, vital and non-vital I/O requirements, and all required interlocking logic. The Microlok II system programmer creates a unique application source file based on the system requirements specified by the application engineer. The programmer uses a standard text editor to create the source file. The source file is given a file name



extension of .ML2. The completed application source file is then processed by the Microlok II logic compiler. The compiler reads the source file and verifies that the content of the file follows the prescribed format and conventions. The compiler produces an application file (.MLP file extension) and a listing file (.MLL extension) that contains a summary 69

of the application program, as well as any errors detected in the source file. Chapter 4 

of this manual covers the operation of the Microlok II logic compiler. Based on the severity and types of errors detected by the compiler, the application source file may need to be corrected using the text editor and run through the compiler again. Steps 2 – 3 are repeated until the compiler produces an acceptable application





file.

Fig-3.11:Process of Application Logic Processing The compiled application file is transferred to a laptop computer and then uploaded to the appropriate Microlok II installation during system startup. The Microlok II



Maintenance Tools program is used to do this. If the proper switch is set in the first line of the application program, the compiler will also generate a debug symbol file with the extension .MLD. This file can then be accessed by the Maintenance Tools program.

3.6.1

Differences Between Microlok And Microlok II

The following is a discussion of the differences between Microlok and Microlok II. In the original Microlok, when a timer bit was assigned a value that required the starting of a timer, the start of that timer was immediate, and the expiration of that timer was permitted to happen when it actually expired.

The following demonstrates how the original MicroLok implemented timers:

70

1. Logic executes and assigns a 1 to the bit named X, and X has a set delay of 500 milliseconds. At that point in time, a 500ms timer is started. 2. Microlok continues to execute other logic. 3. The 500ms timer started in step #1 expires, and X is assigned a 1, and any other logic dependent on X is also triggered. In the above example, the amount of time required to complete step #2 is dependent upon system loading and the amount of logic triggered. If step #2 only required 100 ms, the system would have become stable after step #2, and the outputs would have been delivered. Approximately 400 ms later, the timer would expire and assign a 1 to X. If the amount of time required to complete step #2 exceeded 500 ms, the system would not have become stable, and the output would not have been delivered before X was assigned a 1.

In Microlok II, the implementation of timers was changed so that a timer cannot expire within the same logic cycle in which it was started. In the above example, regardless of the amount of time required to complete step #2, timer X will not be permitted to expire until the system has become stable.

3.6.2

GUIDELINES FOR CREATING AN APPLICATION PROGRAM

The following subsections provide guidelines and conventions that must be observed when creating a Microlok II application source file. 3.6.2.1

Text File Notation

Microlok II programs are free format and are not case sensitive. Comments, which is text ignored by the compiler, begin with a ‘%’ and end with a ‘\’. Single line comments may be identified with ‘//’. Additionally, comments may be delimited with /* and */ .

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The term is used to represent a single application logic Boolean bit. The user specified name consists of numbers and letters. While a name may begin with a number, it must contain at least one letter. For example: flash, 1TK, NWZ. The term is used to represent a list of Boolean bits. Each bit name is separated by a comma. The bit list may contain from 1 to the maximum allowable number of bits.

A term enclosed in brackets < > is meant to represent a special type of user defined bit. For example, in the segment MICROLOK_II PROGRAM ;, the term follows the same rules as a , but the item also has a special meaning, that being the program name. 3.6.2.2

Definitions

Some conventions are used in this document in the definition of the application language for Microlok II. These are: •

All text in this font represents Microlok II program statements.

•

is a user supplied program value. The valid values are explained near the definition.

•

Id names can contain letters or numerals. They may start with a numeral but must contain at least one letter.

• •

is a comma-separated list of valid id names that refer to Boolean bits. is a comma separated list of valid id names that refer to numeric variables.

•

Brackets [ ] are used to enclose optional parts of program statements. The brackets themselves are not part of the program.

•

Structures such as [bill] | [george] indicate that either bill or george can be placed in this location in the program statement.

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•

Structures like [rodger] ... indicate that rodger can be repeated as many times as is necessary at that point in the program.

3.6.2.3

Reserved Words

Reserved words are alphanumeric phrases of up to 16 characters that have a special meaning to the Microlok II compiler. As such, you cannot use reserved words as variables. 3.6.2.4

I/O Board Designations

The purpose of this section is to define the relationships between the I/O boards specified in the user’s application logic program and the board references specified by the Microlok II system. Specifically, when an error is logged, how is the error referenced back to the application logic program? Or when the user displays on the CPU board are active, how do the displays relate back to the actual program and the physical cardfile? The following program example will be used to describe the cross-referencing of I/O boards to the application program: Interface Local Board: relayin Type: IN16 [ADJUSTABLE|FIXED] ENABLE: input: RI1, RI2, RI3, RI4, RI5, RI6, RI7, RI8, RI9, RI10, RI11, RI12, RI13, RI14, RI15, RI16; Board: lampout Type: LAMP16 [ADJUSTABLE|FIXED][[16|18|24|25|36]WATT][MODE [0|1]] Output: L1, L2, L3, L4, L5, L6, L7, L8, L9, L10, L11, L12, L13, L14, L15, L16;

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Board: relayin2 Type: IN16 [ADJUSTABLE|FIXED]ENABLE: input: RI1, RI2, RI3, RI4, RI5, RI6, RI7, RI8, RI9, RI10, RI11, RI12, RI13, RI14, RI15, RI16; Board: nonvital Type: NV.IN32.OUT32 [ADJUSTABLE|FIXED]ENABLE: NV.Output: NVO1, NVO2, NVO3, NVO4, NVO5, NVO6, NVO7, NVO8, NVO9, NVO10, NVO11, NVO12, NVO13, NVO14, NVO15, NVO16, NVO17, NVO18, NVO19, NVO20, NVO21, NVO22, NVO23, NVO24, NVO25, NVO26, NVO27, NVO28, NVO29, NVO30, NVO31, NVO32; NV.Input: NVI1, NVI2, NVI3, NVI4, NVI5, NVI6, NVI7, NVI8, NVI9, NVI10, NVI11, NVI12, NVI13, NVI14, NVI15, NVI16, NVI17, NVI18, NVI19, NVI20, NVI21, NVI22, NVI23, NVI24, NVI25, NVI26, NVI27, NVI28, NVI29, NVI30, NVI31, NVI32;

Board: relayout Type: OUT16 [ADJUSTABLE|FIXED]ENABLE: Output: RO1, RO2, RO3, RO4, RO5, RO6, RO7, RO8, RO9, RO10, RO11, RO12, RO13, RO14, RO15, RO16; Board: noniso Type: CODER.OUT [ADJUSTABLE|FIXED]ENABLE: Output: NIO1, NIO2, NIO3, NIO4;

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In this example, six different physical I/O boards are defined: two standard vital input boards, a lamp driver board, a non-vital I/O board, a vital output board, and a coder output board. Each identified I/O board has a number and/or a name associated with it. The number or name is defined by the user and is a reference for the user; however, the executive software must be able to uniquely identify a board, and the user must be able to determine which specific board is being referenced. 3.6.3

CREATING A MICROLOK II APPLICATION SOURCE FILE

This section provides a comprehensive procedure for creating a Microlok II application source file using a standard Windows-based text editor. (If you use a text editor other than DOS, be sure to save the output file as “text only.”) This section details the basic structure and requirements of the program as well as all of the optional features available to the programmer. 3.6.3.1

Program Structure

The program consists of several major sections that are ordered in the source as they are defined below. A high level view of a Microlok II program looks like:

75

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CHAPTER-4 EVALUATION OF TRAINING The history of signalling dates back to as early as 1814, the year of the first practical use of George Stephenson’s Steam Locomotive. The first rail cars were pulled by horses and mules and were used in mines and quarries. Records as early as 1806 show that hand and arm signals were used to direct the movement of these early trains. Hand signals, flags in day and lanterns at night were used to signal ‘B’ & ‘O’ trains in 1829. In some cases a mounted flagman preceded the train. This system continued in New York city in West St. as late as 1920’s.

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Signalling using fixed track side signals began first in U.S. on New Castle and French Town Railroad in 1832. This 17 mile railroad used fixed signals, flags at first and later ball signals to pass information from one terminal to another.

4.1 BLOCK SIGNALLING The early trains operation was more or less by schedules and hence train separation was by time separation. As traffic increased tracks were divided into blocks and trains separation was by space inte3rval. This is how block 78ignaling began., Various electrical and mechanical systems were tried, the objective being letting one train pass into a block and inhibiting the block entering signal from clearing to allow another train into the block until the first train was reported to have left the block. Subsequently, systems having permissive feature also came into being which allowed trains to follow each other into the same block. From 1851 the telegraph was used to determine the location and progress of trains along the line and to transmit train orders to expedite traffic. All the above systems required substantial manpower and had no protection against a part of a train being accidentally left in a block section between block stations. On 20.10.1872, Dr. William Robinson invented the closed track circuit which gave great fillip in Railway 78ignaling. First installed in Kinzua, PA the closed track circuit quickly proved its worth and other installations involving closed track circuit followed rapidly. All modern track circuits are based on Dr. Robinson’s original concept, even through their capabilities have been greatly enhanced by modern track relays, coding and more recently electronic techniques such as audio and high frequency joint less track circuits. The next advance in block 78ignaling came in 1911 when Sedgwick N. Wight a GRS engineer invested APB i.e. absolute permissive block 78ignaling. This allows train to

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operate in either direction of single track with full signal direction for both following and opposing movement. 4.2 INTERLOCKING The first installation resembling interlocking was installed at Bricklayer’s Arms Junction in England in 1843 wherein switches and signals were operated by a switchman with hand levers and foot stirrups respectively. However, there was no interlocking between switches and signals. Switches were sometimes thrown under trains and signals cleared over open switches but the advantages of centralized control were achieved. In 1856, the first mechanical interlocking incorporating essential interlocking requirements was developed by John Saxby in England. In United States the first interlocking was put in service in 1870 at Trenton, New Jersy. Gradually, mechanical frames were replaced by various types power interlocking, such as hydro pneumatic and electro pneumatic system. In 1901 the Taylor Signal company commissioned the first all-electric, dynamic indication interlocking at Eau Claire, Wis., on the Chicago, St. Paul, Minneapolis and Omaha railway. This system was an immediate success and thousands of levers were installed some of which are still in service. The next development, Relay Interlocking, which requires no mechanical locking between the levers, developed with CTC i.e. Centralised Traffic Control. 4.3 CENTRALISED TRAFFIC CONTROL On July 25th 1927 the first CTC system, invested by Sedgwick N. Wight (the inventor of APB), commissioned between Stanley and Berwick, Ohio on the Ohio Division of New York Central Railroad, This tremendously improved facility and economy in train operation. 4.4 ALL RELAY INTERLOCKING In 1929, GRS commissioned first remotely controlled unit wire all relay interlocking system on the Chicago, Burlington and Quincy at Lincoln, Nebraska.

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The first installation of all relay Interlocking with push button, automatic selection of routes and positioning of switches and signals, the GRS type NX, was made at Brunswick, England on the Cheshire Lines, in February 1937. The first NX route-type interlocking in the United States was installed at Girard Jct., Ohio, on the New York Central in 1937.

CHAPTER -5 CONCLUSION AND FUTURE SCOPE OF TRAINING Train Control Systems for Increasing Train Intelligence The on-board digital ATC system capabilities described are certain to become much more advanced and intelligent than the train control systems that we have had up to now. Further development of digital processing technology will enable more sophisticated functions and smarter on-board systems.

Fig-5.1:Rail Transportation System Fig. 5.1 shows a schematic overview of a train control system that can accommodate more intelligent on-board systems. The track-side system manages all the information coming from the on-board system (location information, etc.), and transmits whatever 80

information is needed for safe running to all the trains in the vicinity (stopping positions, speed limits, etc.). In other words, the system consists of three elements: 

The track-side system manages overall safety.



The on-board system exercises autonomous running control within the scope guaranteed by the track-side system.



Continuous communication is supported between the track-side and on-board systems. Communication between the track-side and onboard systems will use a number of different media including rail-based transmission such as the digital ATC signal, LCX (leaky coaxial) cable, and space wave and other wireless transmission schemes.

Trains are able to run autonomously and safely based on their own on-board systems using route data that is stored in the train’s on-board database. Specifically, the onboard system detects and manages the train’s own position vis-à-vis the stopping position that is sent from the track-side system. The on-board system generates its own speed check profile permitting safe running by means of sequential computation based on the route data—current position, curves, inclines, branch restrictions—and controls the speed of the train accordingly. Essentially, this means that each train can run flexibly in accordance with its own autonomous and line transport requirements within the scope guaranteed by the track-side system. Moreover, with increasing track-side-on-board transmission capacity and more advanced functionality of onboard equipment, this will permit more extensive operating support information for crew members. And at the same time on-board equipment becomes more intelligent, the dependence of conventional train control systems on wayside signals, beacons, ground coils, and other track-side equipment will diminish, and this will reduce the 81

volume and the cost of these track-side facilities. This should also improve the flexibility and expandability of the system as a whole.

APPENDIX I Reserved Words for the Microlok II Compiler ADDRESS ADJ ADJUSTABLE AFTER AND ARRAYS ASSIGN ATTRIBUTES BAUD BEGIN BIT BITS BLOCK BOARD BOOLEAN CAB FREQUENCY CAB RATE CARRIER MODE CLEAR 82

CODE SUBSET CODED CODER OUT COMM CONFIGURATION CONSTANT CONSTANTS CRC SIZE DEBUG PORT ADDRESS DEBUG PORT BAUDRATE DELAY RESET E TRACK ELSE ENABLE END ERROR EVALUATE EVEN EXECUTIVE FUNCTION FAST CODES FIX FIXED FOR FROM

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GENISYS GENISYS MASTER GENISYS SLAVE IF IN16 IN8 OUT8 INITIALIZE TIMER INITIALIZED INPUT INPUTS INTERBYTE TIMEOUT INTERFACE INTERPOLATE KEY OFF DELAY KEY ON DELAY KEYED LAMP OUT LAMP16 LENGTH LINK LOCAL LOG LOGIC LOGIC TIMEOUT MAP

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MARK MASTER MASTER CHECKBACK MASTER TIMEOUT MICROLOK MICROLOK MASTER MICROLOK SLAVE MICROTRAX MIN MOD MODE MSEC NAME NONE NOT NUMERIC NUMERIC INPUT NUMERIC OUTPUT NUMERICS NV ASSIGN NV BOOLEAN NV EVALUATE NV IN32 OUT32 NV INPUT NV NUMERIC

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NV NUMERIC INPUT NV NUMERIC OUTPUT NV OUTPUT NVB OUT12 ODD OFF ON OR OUT16 OUTPUT OUTPUTS OVERRANGE PARITY POINT POINT POLLING INTERVAL PORT PRAGMA PROGRAM PROTOCOL QUESTION RANGES RESTART TIMER ROUND SEC SECTION

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SECURE MODE SET SHARED RAM SHUTDOWN SLAVE SLOT SPACE STALE STALE DATA TIMEOUT STANDARD STATE STOPBITS SYSTEM TABLE TABLES THEN TIME SINCE START TIMER TO TOGGLE TRACK TRACK NAME TRACKA TRACKB TRIGGERS

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TRUNCATE TRX TRACK TYPE UNDEFINED REFERENCES 1. http://www.asa.transport.nsw.gov.au 2. http://www.ansaldo-sts.com 3. http://www.wikupedia.org 4. http://www.rdso.indianrailways.gov.in 5. http://www.mlc-rail.com 6. http://www.mmrda.maharastra.gov.in 7. http://www.railway-technology.com 8. http://www.moxa.com 9. http://www.railwaysignalling.eu 10. http://www.edmi-meters.com 11. http://www.pheonixcontact.com

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