Power Quality notes
Short Description
Power Quality...
Description
POWER QUALITY
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What is Power Quality ? Any power problem manifested in voltages, current, or
frequency deviations that results in failure or disoperation of customer equipment. In broadest sense, power quality is a set of boundaries that allows electrical systems to function in their intended manner without significant loss of performance or life. The term is used to describe electric power that drives an electrical load and the load's ability to function properly with that electric power. Without the proper power, an electrical device (or load) may malfunction, fail prematurely or not operate at all 2
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IEEE Definition Institute of Electrical and Electronic Engineers (IEEE) Standard
IEEE1100 defines power quality as “the concept of powering and grounding sensitive electronic equipment in a manner suitable for the equipment.” All electrical devices are prone to failure or malfunction when exposed to one or more power quality problems. The electrical device might be an electric motor, a transformer, a generator, a computer, a printer, communication equipment, or a household appliance. All of these devices and others react adversely to power quality issues, depending on the severity of problems.
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TWO DIFFERENT CASES 100 Watts Bulb
Std. 100 W bulb requires 230 V to
produce the required Lumens of light output.
If Voltage drops 10% ? What happens if there is Complete
Outage or blackouts ?
If Voltage raises 10% ? 4
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CRT Monitor of PC
CRT Monitor for PC uses a 230 V AC
Power Supply which is converted in to 5 V DC for logic circuits & high voltage DC to operate CRT.
If Voltage drops 10% ? If Voltage raises 10% ?
POWER QUALITY ISSUES Power Quality Disturbances have been organized into seven categories based on wave shape: 1. Transients 2. Voltage Sag 3. Voltage Swell 4. Interruption 5. Waveform Distortion 6. Voltage Fluctuations 7. Frequency Variations 5
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What is a Transient or Surge? A“typical” lightning stroke can carry nearly 3 billion kW at approximately 125 million volts, with an average current of more than 20,000A. Lightning also produces extremely powerful, short-duration transients on power distribution systems — either by a direct strike or a near hit. In most instances, a lightning strikeinduced surge on local power distribution lines causes damage to susceptible equipment.
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It can also have secondary effects that cause problems to susceptible electronic equipment in a building. CBs protecting utility lines can trip and then try to reclose. The resulting voltage sags and outages can cause more problems to computers and other electronic devices than the voltage transients themselves.
What is a Transient or Surge?
Fig: Typical utility capacitor-switching transients can reach 134% of nominal voltage "up line" from the capacitor.
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Continuous surges. These surges, which can range from 250V to 1,000V, can come from operation of electric motors or other inductive loads. Other causes include DC motor drives, the power electronics of VSDs, DC power supply switching, and even portable tools.
Momentary surges. These surges, which can range from 250V to 3,000V, can originate from the switching of inductive loads. When you interrupt an inductor's current, a surge voltage will be generated. Its magnitude is described by the equation e = L × di/dt,
The opening and closing of electric motor starters or the use of arc welders and furnace igniters can induce these surges. When the conductors carrying these surge currents are in proximity to conductors of signaling or data circuits, induced voltages will be generated within these circuits. The result is the introduction of electrical noise and loop currents.
Deenergizing inductive circuits with air-gap switches such as relays and contactors, can generate bursts of highfrequency impulses.
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Sources of Transients Lightning
�� Static �� Arc Welding Switching
�� Contactor �� Relays �� SCR’s
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What is a Transient or Surge? A Transient can be classified into two categories, impulsive and oscillatory Duration < 50 ns to 50 ms
�� .00000005 seconds to .002 seconds �� .000005 seconds to .050 seconds
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Transient Overvoltage Transient overvoltage are brief, high-frequency increases in
voltage on AC mains.
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Capacitor Bank Switch
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Transient Overvoltage There
are two different types of transient overvoltage: a)low frequency transients : frequency components in the fewhundred-hertz region typically caused by capacitor switching . Low frequency transients are often called "capacitor switching transients".
These transients are caused when a discharged power-factor-
correction capacitor is switched on across the line. The capacitor then resonates with the inductance of the distribution system, typically at 400 - 600 Hz, and produce and exponentially damped decaying waveform. The peak of this waveform, in theory, cannot exceed twice the peak voltage of the sine wave, and is more typically 120% - 140% of the sine peak.
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Transient Overvoltage b)high-frequency transients :frequency components in the
few-hundred-kilohertz region typically caused by lighting and inductive loads turning off. High frequency transients are often called "impulses", "spikes", or "surges".
Typical rise times are on the order of a microsecond; typical
decay times are on the order of a tens to hundreds of microseconds. Often, the decay will be an exponential damped waveform, with a frequency of approximately 100 kHz, which corresponds to the frequency of equivalent inductor/capacitor model of low voltage power lines. Typical peak voltages for end-use applications are hundreds of volts to a few thousand volts; several thousand amps of current may be available.
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Voltage Transients - Simulation
In this disturbance, the nominal voltage is increased to high value for a moment during fault, this is generated by rapid switching on the source side. In the above circuit the voltage transient is created using rapid switching by breaker before the bus bar that is on the distribution side has been switched on and off by giving values in the switching times in the block parameters. After simulating we can see the output waveform in the scope of the above model.
The above waveform is done by including a negative gain in between the scope and the voltage measurement block, here the voltage transient will persists for only a moment for that moment the voltage value will be increased to a high value thus it is called voltage transient. 23
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Introduction to the most common disturbance on AC mains Voltage Sags (dips) , Voltage Swells and Flickering Voltage sags -- or dips which are the same thing -- are brief reductions in voltage,
typically lasting from a cycle to a second or so, or tens of milliseconds to hundreds of milliseconds. It is caused by abrupt increases in loads such as short circuits or faults, motors starting, or electric heaters turning ON, or they are caused by abrupt increases in source impedance, typically caused by a loose connection
Voltage swells are brief increases in voltage over the same time range.
Voltage swells are almost always caused by an abrupt reduction in load on a circuit with a poor or damaged voltage regulator, although they can also be caused by a damaged or loose neutral connection. Flicker : Random or repetitive variations in the RMS Voltage between 90% and 110% of
nominal can produce a phenomenon known as flicker in lighting equipment
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A typical voltage sag
Voltage sags are the most common power disturbance. At a typical industrial site, it is
not unusual to see several sags per year at the service entrance, and far more at equipment terminals.
Voltage sags can arrive from the utility; however, in most cases, the majority of sags are
generated inside a building. For example, in residential wiring, the most common cause of voltage sags is the starting current drawn by refrigerator and air conditioning motors.
Sags do not generally disturb incandescent or fluorescent lighting,motors, or heaters.
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However, some electronic equipment lacks sufficient internal energy storage and, therefore, cannot ride through sags in the supply voltage. Equipment may be able to ride through very brief, deep sags, or it may be able to ride through longer but shallower sags. AP/EEE/KEC/PERUNDURAI M.SURESH
Simulation - Sag
In this disturbance, the nominal voltage is reduced to get the fault period. This is generated by creating a short circuit for a small period. In the above circuit the sag is created using short circuit by breaker. A load that has been switched ON and OFF by giving values in the switching times in the block parameters. After simulating we can see the output waveform in the scope of the above model. The above waveform is done by including a negative gain in between the scope and the voltage measurement block, here the voltage sag is persists for around 6 cycles you can note that for those 6 cycle the voltage value is reduced.
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Voltage Swell A swell is the reverse form of a sag, having an increase in AC
voltage for a duration of 0.5 cycles to 1 minute’s time. For swells, high-impedance neutral connections, sudden (especially large) load reductions, and a single-phase fault on a three-phase system are common sources.
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Simulation - Swell
In this disturbance, the nominal voltage is increased to get the fault period. In the above circuit the swell is created using rapid switching by breaker. A load that has been switched ON and OFF by giving values in the switching times in the block parameters. After simulating we can see the output waveform in the scope of the above model.
The above waveform is done by including a negative gain in between the scope and the voltage measurement block, here the voltage swell is persists for around 6 cycles you can note that for those 6 cycle the voltage value is increased. 28
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A Practical Approach Induction Motor
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Voltage sags typically are due to starting on large loads, such as an electric motor or an arc furnace. Induction motors draw starting currents ranging between 600 and 800% of their nominal full load currents. The current starts at the high value and tapers off to the normal running current in about 2 to 8 sec, based on the motor design and load inertia. Depending on the instant at which the voltage is applied to the motor, the current can be highly asymmetrical.
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A Practical Approach Figure 1.contains the waveform of the starting current of a 50-hp induction motor with a
rated full-load current of 60 A at 460 V AC. During the first half of the cycle, the asymmetrical current attains a peak value of 860 A. When the circuit feeding the motor has high impedance, appreciable voltage sag can be produced.
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FIGURE .1 Motor-starting current waveform. A 50-hp motor was started across the line.The motor full-load current was 60 A.The first half-cycle peak reached a value of 860 A. AP/EEE/KEC/PERUNDURAI M.SURESH
A Practical Approach Figure 2 shows a 100-kVA transformer feeding the 50-hp motor just described. If
the transformer has a leakage reactance of 5.0%, the voltage sag due to starting this motor is calculated as follows:
Full load current of the 100-kVA transformer at 480V = 120 A. Voltage drop due to the starting inrush = 5.0 × 860 ÷(120 × √2) = 25.3%
If the reactance of the power lines and the utility transformer feeding this transformer
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were included in the calculations, the voltage sag would be worse than the value indicated. It is not difficult to see that any device that is sensitive to a voltage sag of 25% would be affected by the motor starting event.. M.SURESH AP/EEE/KEC/PERUNDURAI
Practical Approach Arc Furnace An electric arc furnace is a system that heats charged material by means of an electric arc. Arc furnaces range in size from small units of approximately one ton capacity used in foundries for producing cast iron products, up to about 400 ton units used for secondary steelmaking (arc furnaces used in research laboratories and by dentists may have a capacity of only a few dozen grams). Temperatures inside an electric arc furnace can rise to approximately 1800 degrees Celsius
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Graphite Electrode
Electric Arc 36
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A Practical Approach Arc furnaces are another example of loads that can produce large voltage sags in electrical power systems. Arc furnaces operate by imposing a short circuit in a batch of metal and then drawing an arc, which produces temperatures in excess of 10,000°C, which melt the metal batch. Arc furnaces employ large inductors to stabilize the current due to the arc. Tens of thousands of amperes are drawn during the initial few seconds of the process
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FIGURE Typical current draw by arc furnace at the primary transformer. Large current fluctuations normally M.SURESH AP/EEE/KEC/PERUNDURAI occur for several seconds before steady state is obtained
A Practical Approach Due to the nature of the current drawn by the arc furnace, which is
extremely nonlinear, large harmonic currents are also produced. Severe voltage sags are common in power lines that supply large arc furnaces, which are typically rated in the 30- to 50-MVA range and higher. Arc furnaces are operated in conjunction with large capacitor banks and harmonic filters to improve the power factor and also to filter the harmonic frequency currents so they do not unduly affect other power users sharing the same power lines. Utility faults are also responsible for voltage sags. Approximately 70% of the utility-related faults occur in overhead power lines. Some common causes of utility faults are lightning strikes, contact with trees or birds and animals, and failure of insulators. The utility attempts to clear the fault by opening and closing the faulted circuit using reclosers, which can require from 40 to 60 cycles. The power line experiences voltage sags or total loss M.SURESH AP/EEE/KEC/PERUNDURAI 38 of power for the short duration it takes to clear the fault.
Voltage Sag @ Refinery – Utility Fault
FIGURE :Voltage sag at a refinery due to a utility fault.The sag caused the programmable logic controller to drop out, which resulted in interruption of power.The sag lasted for approximately 21 cycles.
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Voltage Sag @ Al. Smelter – Utility Fault
FIGURE : Voltage sag caused by utility switching at an aluminum smelter. The sag lasted for five cycles and caused motor controllers to drop out. 40
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Voltage sag due to generator step load application
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FIGURE :Voltage sag due to generator step load application.The nominal 480-V generator bus experienced a sag to 389 V that lasted for approximately 1 sec.
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Voltage swell due to step load rejection
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FIGURE :Voltage swell due to step load rejection. The nominal 480-V generator experienced a rise to 541V that lasted for approximately 18 cycles. M.SURESHbus AP/EEE/KEC/PERUNDURAI
Interruptions An interruption is defined as the complete loss of supply voltage or load current. Depending on its duration, an interruption is categorized as instantaneous, momentary, temporary, or sustained. Duration range for interruption types are as follows: Instantaneous - 0.5 to 30 cycles Momentary
- 30 cycles to 2 seconds
Temporary
- 2 seconds to 2 minutes
Sustained greater than 2 minutes
Fig - Momentary interruption
The causes of interruptions can vary, but are usually the result of some type of electrical supply grid damage, such as lightning strikes, animals, trees, vehicle accidents, destructive weather (high winds, heavy snow or ice on lines, etc.), equipment failure, or a basic circuit breaker tripping.This interruptions can be observed in the above fig.
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An interruption, whether it is instantaneous, momentary, temporary, or sustained, can cause disruption, damage, and downtime, from the home user up to the industrial user. A home, or small business computer user, could lose valuable data when information is corrupted from loss of power to their equipment. M.SURESH AP/EEE/KEC/PERUNDURAI
Momentary Interruptions
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Outage
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Interruptions - Simulation
In this disturbance, the nominal voltage will be zero for a period of time, this is generated by rapid switching on the source side. In the above circuit the voltage interruption is created using rapid switching by breaker before the bus bar that is on the distribution side has been switched on and off by giving values in the switching times in the block parameters. After simulating we can see the output waveform in the scope of the above model.
The above waveform is done by including a negative gain in between the scope and the voltage measurement block, here the voltage interruption will persists for only a period of time for that period the voltage value will be zero thus it is called voltage interruption or outages. 46
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Causes of Sag, Interruptions Outages
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Simplified Utility System
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Example
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Simplified Utility System
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Waveform Distortion There are five primary types of waveform distortion: 1. DC offset 2. Harmonics 3. Interharmonics 4. Notching 5. Noise
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DC offset
Direct current (DC) can be induced into an AC distribution system, often due to failure of rectifiers and Geo Magnetic disturbances ( GMD). It adds unwanted current to devices already operating at their rated level. Overheating and saturation of transformers can be the result of circulating DC currents. When a transformer saturates, it not only gets hot, but also is unable to deliver full power to the load, and the subsequent waveform distortion can create further instability in electronic load equipment. Fig shows the DC offset
The solution to dc offset problems is to replace the faulty equipment that is the source of the problem. Having very modular, user replaceable, equipment can greatly increase the ease to resolve dc offset problems caused by faulty equipment, with less costs than may usually be needed for specialized repair labor. 52
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What are Harmonics? Harmonics are sinusoidal voltages or currents having frequencies that are multiples of the frequency at which the supply system is designed to operate, that combine with the fundamental voltage or current, and produce waveform distortion.
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Harmonics Harmonic distortion is the corruption of the fundamental sine wave at
frequencies that are multiples of the fundamental. (e.g., 150Hz is the third harmonic of a 50Hz fundamental frequency; 3 X 50 =150). Symptoms of harmonic problems include overheated transformers, neutral conductors, and other electrical distribution equipment, as well as the tripping of circuit breakers and loss of synchronization on timing circuits that are dependent upon a clean sine wave trigger at the zero crossover point. Fig shows the waveform distortion
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Fig: Harmonic Waveform Distortion M.SURESH AP/EEE/KEC/PERUNDURAI
A Pure Sine Wave
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Fundamental with 5th harmonics
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Distortion produced by 5th order
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Fundamental with 7th harmonics
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Distortion produced by 7th order
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Fundamental with 5th & 7thHarmonics
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Creation of Non Linear Wave form
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Potential sources of Harmonics SMPS Dimmers Current regulators Power electronic converters Low power consumption lamps Arc welding machines Induction motor with irregular magnetizing current associated with saturation of the iron • All equipment with built-in switching devices or with internal loads with non-linear voltage/current characteristics • • • • • • •
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Causes for Harmonic Distortion Harmonic distortion has been a significant problem with IT equipment in the past, due to the nature of switch-mode power supplies (SMPS). These non-linear loads, and many other capacitive designs, instead of drawing current over each full half cycle, “sip” power at each positive and negative peak of the voltage wave. The return current, because it is only short-term, (approximately 1/3 of a cycle) combines on the neutral with all other returns from SMPS using each of the three phases in the typical distribution system. Instead of subtracting, the pulsed neutral currents add together, creating very high neutral currents, at a theoretical maximum of 1.73 times the maximum phase current. An overloaded neutral can lead to extremely high voltages on the legs of the distribution power, leading to heavy damage to attached equipment. At the same time, the load for these multiple SMPS is drawn at the very peaks of each voltage half-cycle, which has often led to transformer saturation and consequent overheating. Other loads contributing to this problem are variable speed motor drives, lightning ballasts and large legacy UPS systems. Methods used to mitigate this problem have included over-sizing the neutral conductors, installing K-rated transformers, and harmonic filters. 67
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Why Worry?
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Why Worry?
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IEEE Harmonic Standards Bus voltage at PCC
Individual THD (%) voltage distortion (%)
69 KV & below
3.0
5.0
69.001KV 161KV
1.5
2.5
161.001KV & above
1.0
1.5
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Harmonics The electric power distribution system is designed to operate with sinusoidal voltages and
currents. But not all waveforms are sine waves. Electronic loads, for example, often draw current only at the peak of the voltage waveform, which always means that the current is distorted, and may distort the voltage as well. One convenient way to describe these waveforms is to make a list of sine waves that, when added together, reproduce the distorted waveform. The sine waves in this list are always multiples, or harmonics, of the fundamental frequency (50 Hz or 60 Hz).
A typical distorted current waveform, drawn by the supply above. It only draws current at the peak of the voltage waveform, because the diodes in BR1 only conduct when the AC voltage is higher than the voltage on C1.
A typical input circuit of a single-phase supply.
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This is the same waveform, expressed as a frequency spectrum. Note that the frequency content of the waveform consists of odd multiples (3,5,7,9, etc.) of the fundamental. This is typical for electronic loads.
Interharmonics Interharmonics are a type of waveform distortion that are usually the result of a signal
imposed on the supply voltage by electrical equipment such as static frequency converters, induction motors and arcing devices. Cycloconverters (which control large linear motors used in rolling mill, cement, and mining equipment), create some of the most significant interharmonic supply power problems. These devices transform the supply voltage into an AC voltage of a frequency lower or higher than that of the supply frequency. Interharmonics can be clearly seen in fig
The most noticeable effect of interharmonics is visual flickering of displays and incandescent lights, as well as causing possible heat and communication interference.
Fig .Interharmonic Waveform Distrotion Solutions toAP/EEE/KEC/PERUNDURAI interharmonics include filters, UPS systems, and line conditioners. M.SURESH
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Harmonics are bad! Excessive losses and heating in motors, transformers
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and capacitors connected to the system Insulation failure due to overheating and over voltages Malfunctioning of sophisticated electronic equipments Over loading and over heating of neutral conductors with loss of conductor life and possible risk of fire Saturation of transformers Interference with communication network
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Notching Notching is a periodic voltage disturbance caused by electronic devices, such as variable speed drives, light dimmers and arc welders under normal operation. This problem could be described as a transient impulse problem, but because the notches are periodic over each ½ cycle, notching is considered a waveform distortion problem. The usual consequences of notching are system halts, data loss, and data transmission problems. It can be seen clearly in fig
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Fig - Notching One solution to notching is to move the load away from the equipment causing the problem (if possible). UPSs and filter equipment are also M.SURESH AP/EEE/KEC/PERUNDURAI viable solutions to notching if equipment cannot be relocated.
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Noise Noise is unwanted voltage or current superimposed on the power system voltage or current waveform. Noise can be generated by power electronic devices, control circuits, arc welders, switching power supplies, radio transmitters and so on. Poorly grounded sites make the system more susceptible to noise. Noise can cause technical equipment problems such as data errors, equipment malfunction, longterm component failure, hard disk failure, and distorted video displays. Fig . shows the noise in the waveform. There are many different approaches to controlling noise and sometimes it is necessary to use several different techniques together to achieve the required result. Some methods are: • Isolate the load via a UPS • Install a grounded, shielded isolation transformer • Relocate the load away from the interference source • Install noise filters • Cable shielding
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Voltage Fluctuations Since voltage fluctuations are fundamentally different from the rest of the waveform
anomalies, they are placed in there own category. A Voltage fluctuation is a systematic variation of the voltage waveform or a series of random voltage changes, of small dimensions, namely 95 to 105% of nominal at a low frequency, generally below 25 Hz.This can be clearly seen in fig.
Fig -Voltage Fluctuation Any load exhibiting significant current variations can cause voltage fluctuations.
Arc furnaces are the most common cause of voltage fluctuation on the transmission and distribution system. One symptom of this problem is flickering of incandescent lamps. Removing the offending load, relocating the sensitive equipment, or installing power line conditioning or UPS devices, are methods to resolve this problem.
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Frequency Variations
Frequency variation is extremely rare in stable utility power systems, especially systems interconnected via a power grid. Where sites have dedicated standby generators or poor power infrastructure, frequency variation is more common especially if the generator is heavily loaded. IT equipment is frequency tolerant, and generally not affected by minor shifts in local generator frequency. What would be affected would be any motor device or sensitive device that relies on steady regular cycling of power over time. Frequency variations may cause a motor to run faster or slower to match the frequency of the input power. This would cause the motor to run inefficiently and/or lead to added heat and degradation of the motor through increased motor speed and/or additional current draw. Frequency variations can be seen in fig
Fig - FrequencyVariation To correct this problem, all generated power sources and other power sources causing the frequency
variation should be assessed, then repaired, corrected, or replaced.
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Duration ��Transient or Surge (Impulse)
�� .00000005 -- .002 sec
��Transient or Surge (Oscillatory)
�� .000005 -- .050 sec
�� Sag
�� .008 -- 1 min
�� Swell
�� .008 -- 1 min
�� Momentary Interruption
�� .008 -- 3 sec
�� Interruption
�� 3 sec to 1 min
�� Outage
�� Greater than 1 min
�� Harmonics
�� Steady State Condition
�� Unbalance
�� Steady State Condition
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Customized Solutions
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Customized Solutions
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Customized Solutions
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Customized Solutions
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Flicker Flicker is a very specific problem related to human perception and incandescent light bulbs.
It is not a general term for voltage variations. Humans can be very sensitive to light flicker that is caused by voltage fluctuations. Human perception of light flicker is almost always the limiting criteria for controlling small voltage fluctuations. The figure illustrates the level of perception of light flicker from a 60 watt incandescent bulb for rectangular variations. The sensitivity is a function of the frequency of the fluctuations and it is also dependent on the voltage level of the lighting.
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Voltage Regulation The term "voltage regulation" is used to discuss long-term variations
in voltage. It does not include short term variations, which are generally called sags, dips, or swells. The ability of equipment to handle steady state voltage variations varies from equipment to equipment. The steady state voltage variation limits for equipment is usually part of the equipment specifications. The Information Technology Industry Council (ITIC) specifies equipment withstand recommendations for IT equipment according to the ITI Curve (formerly the CBEMA curve). The 1996 ITI Curve specifies that equipment should be able to withstand voltage variations within +/- 10% (variations that last longer than 10 seconds). 88
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Other Disturbances The most common disturbances on AC power systems are voltage sags or dips. Other
problems, such as transient overvoltage and brief interruptions, occur almost everywhere. Problems with harmonics, voltage regulation, and flicker occur at a wide range of sites. Some other disturbances that occur at specific locations include:
Frequency variations. On utility grids, these are rare events, usually associated with
catastrophic collapses on the grid. However, at sites with back-up diesel generators, they are common.
High frequency noise. This can be caused by anything from arcing brushes on a motor,
to local radio transmitters.
Mains signaling Some utilities intentionally place small signals on the mains voltage to
act as control signals (for example, they may control a capacitor switch, or they may instruct revenue meters to go to a different rate structure).
EFT Extremely Fast Transients are nano-second range transient overvoltage. Due to their
high frequency content, they do not travel well over the mains circuits, getting damped out within a few meters. However, they can be caused by nearby contact arcing.
Unbalance On three-phase systems, the voltages and currents on each phase should, in 89
theory, matchAP/EEE/KEC/PERUNDURAI the voltages and currents on the other phases. Sometimes they don't. M.SURESH
IEEE PQ Standards
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Electromagnetic Compatibility Electromagnetic compatibility is the capability of electrical and electronic systems,
equipments, and devices to operate in their intended electromagnetic environment within a defined margin of safety, and at design levels or performance, without suffering or causing unacceptable degradation as a result of electromagnetic interference. Eg: Switching off your electronics devices when you are taking a flight
As more electronics products e.g. handphones, radio transmitters, solid state
switching devices, motor drives devices are developed and push to the market, the increase of electromagnetic pollution is on the rise everyday. These devices caused emissions to the environment where it was used.
As a result of these emissions, they will affect other electronic equipment which is
susceptable to these emissions. As more microprocessors are used to replace analog or mechanical means of a product, it become apparent that the issue of EMC cannot be ignored. Ignoring this will caused the product to suddenly malfunction or even caused damage to properties or lives.
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EMC Standard In order to ensure that the equipments are designed to perform as close as possible in its environment, the European standards making body CENELEC(European Committee for Electrotechnical Standardization) has been mandated to produce standards for use with the European EMC Directive. For telecommunications equipment ETSI(European Telecommunications Standards Institute) is the mandated standards body. There are 3 types of standards :
a) Product or product family standards, relating to a specific product or product family group. The product standards take precedence over the generic standards and are drafted to cover the particular range of product types.These standards should refer to the Basic Standards for test methods wherever possible. It wil consist of defining what tests to carry out, what levels or limits, and what operating conditions and performance criteria to apply. These are prepared by IEC, CENELEC or CISPR.
b) Generic Standards relating to a particular environment of use. At present these are for: (i) Domestic, Commercial and Light Industry (ii) Industrial environment
c) Basic Standards, to provide general information and relate to the disturbing phenomena and testing and measuring techniques. Basic standards do not contain limits or performance criteria. They serve as a reference for product standards and will not normally be listed in the Official Journal, but will be referred to in product or generic standards.
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EMC Standard List of Product Standards related to household electrical appliances i) EN 55014 Limits and methods of measurements of radio disturbance charateristics of
household electrical appliances, portable tools, and similar electrical apparatus (CISPR 14).
ii) EN 55015 Limits and methods of measurement of radio disturbance characteristics
of electrical lighting and similar equipment (CISPR 15).
iii) EN 55104 Electromagnetic compatibility - immunity requirements for household
appliances, tools and similar apparatus (CSIPR 14-2)
Generic Standards - Emissions i) EN 50081 Part 1 Generic emission standard, part 1: Residential, commercial and
light industry environment.
ii) EN 50081 Part 2 Generic emission standard, part 2: Industrial environment.
Generic Standards - Immunity i) EN 50082 Part 1 Generic immunity standard, part 1: Residential, commercial and
light industry environment.
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M.SURESH AP/EEE/KEC/PERUNDURAI ii) EN 50082 Part 2 Generic immunity standard, part 2: Industrial environment
EMC Standard
Basic Standards
i) EN 61000-3-2 Electromagnetic compatibility (EMC). Limits. Limits for harmonic current emissions (equipment input current up to and including 16 A per phase)
ii) EN 61000-3-3 Electromagnetic compatibility (EMC). Limits. Limitation of voltage changes, voltage fluctuations and flicker in public low-voltage supply systems, for equipment with rated current 16 A per phase and not subject to conditional connection.
iii) EN 61000-4-1 Electromagnetic compatibility (EMC). Testing and measurement techniques. Overview of IEC 61000-4 series.
iv) EN 61000-4-2 Electromagnetic compatibility (EMC). Testing and measurement techniques. Electrostatic discharge immunity test. Basic EMC publication.
v) EN 61000-4-3 Electromagnetic compatibility (EMC). Testing and measurement techniques. Radiated, radio-frequency, electromagnetic field immunity test.
vi) EN 61000-4-4 Electromagnetic compatibility (EMC). Testing and measurement techniques. Electrical fast transient/burst immunity test. Basic EMC publication.
vii) EN 61000-4-5 Electromagnetic compatibility (EMC). Testing and measurement techniques. Surge immunity test.
viii) EN 61000-4-6 Electromagnetic compatibility (EMC). Testing and measurement techniques. Immunity to conducted disturbances, induced by radiofrequency fields.
ix) EN 61000-4-7 Electromagnetic compatibility (EMC). General guide on harmonics and interharmonics measurements and instrumentation, for power supply systems and equipment connected thereto.
x) EN 61000-4-8 Electromagnetic compatibility. Testing and measurement techniques. Power frequency magnetic field immunity test. Basic EMC publication.
xi) EN 61000-4-9 Electromagnetic compatibility (EMC). Testing and measurement techniques. Pulse magnetic field immunity test. Basic EMC publication.
xii) EN 61000-4-10 Electromagnetic compatibility (EMC). Testing and measurement techniques. Damped oscillatory magnetic field immunity test. Basic EMC publication.
xiii) EN 61000-4-11 Electromagnetic compatibility (EMC). Testing and measurement techniques. Voltage dips, short interruptions and voltage variations immunity tests.
xiv) EN 61000-4-12 Electromagnetic compatibility (EMC). Testing and measurement techniques. Oscillatory waves immunity test. Basic EMC publication.
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The Bigger Picture
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The Bigger Picture
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