Design And Construction Of Under And Over Voltage Power Protection System

DESIGN AND CONSTRUCTION OF UNDER AND OVER VOLTAGE POWER PROTECTION SYSTEM ABSTRACT The power line fluctuations and cut-offs or power failure causes damages to electrical appliances connected to the line. It is more serious in the case of domestic appliances like fridge and air conditioners. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged. Low and high voltage monitor is a device designed to protect electrical appliances from over voltage as well as under voltage. The under/over voltage monitor circuit with time delay presented in this w ork is a low cost and reliable circuit for protecting such equipments from damages. Whenever the power line is switched on it gets connected to the appliance only after a delay of a fixed time. t ime. If there is hi/low fluctuations beyond sets limits the appliance get disconnected. The system tries to connect the power back after the specific time delay, the delay being counted from the time of disconnection. If the power down time (time for which w hich the voltage is beyond limits) is less than the delay time, t ime, the power resumes after the delay: If it is equal or more, then the power resumes directly.

TABLE

OF

Title Approval Dedication Acknowledgement Abstract Table

CONTENT

Page Page

of

Content

CHAPTER

1.0 1.1 1.2 1.3 1.4

ONE

objective significance applications

advantages CHAPTER

and

of of of applications

Introduction project project project

the the the of

the

project TWO

2.0 2.1

literature review of voltage regulation

2.2

overvoltage to homes appliances

CHAPTER

3.0 3.2 3.3 3.4 3.5 3.6

THREE

Construction/ Methodology block diagram of the project circuit diagram of the project system operation circuit description Description of major components used

CHAPTER

4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7

FOUR

Result analysis installation of the complete design construction procedure and testing casing and packaging assembling of section testing of system operation problems encountered cost analysis

CHAPTER

5.1 5.2 5.3

review

FIVE

Conclusion Recommendation Bibliography

CHAPTER INTRODUCTION

ONE

Low and high voltage monitor is a device designed to protect electrical appliances from over voltage as well as under voltage. The under/over voltage protection circuit with time delay presented in this work is a low cost and reliable circuit for protecting such equipments from damages. Whenever the power line is switched on it gets connected to the appliance only after a delay of a fixed time. If there is hi/low fluctuations beyond sets limits the appliance get disconnected. The system tries to connect the power back after the specific time delay, the delay being counted from the time of disconnection. If the power down time (time for which the voltage is beyond limits) is less than the delay time, the power resumes after the delay: If it is equal or more, then the power resumes directly.

This work provides few circuit ideas that can provide low voltage and over voltage protection to connected electrical assets. Though these circuits won’t be able to stabilize the input voltage, even so may prove very effective in providing total safety to your precious electrical home appliances against dangerous input voltages. The first design of a low voltage indicator circuit may be used to indicate the presence of dangerous low voltage conditions. A low voltage may appear to be something that is lower in magnitude and power, but that is what makes it more lethal. For example a refrigerator working at 230 volts AC mains will never “like” voltages below 190, since in such cases its compressor due to the lack of sufficient voltage, will try to compensate by drawing heavy currents and may get damaged if the situation persists. The same is true for other types of AC operated motors. Also in vehicles, for example a car, if the battery voltage falls below 9 volts, it may be quite harmful for the life of the battery itself and moreover the vehicle will just not start at that voltage. 1.2

OBJECTIVE

OF

THE

PROJECT

The objective of this work is: 



Provide a solution to under voltage and over situation faced by residents of high density areas of Nigeria by designing and constructing an effective and comparatively cheaper voltage stabilizer which will have a cost price of less than total cost obtained which could be afforded by most low income earners. To regulate the voltage of there is any over voltage or under voltage an regulate the voltage that will suit the purpose the analysis design, construction and cost comparison have been done and necessary tests have been satisfactory out.

1.3

SIGNIFICANCE

OF

THE

STUDY

As a student of electrical and electronic engineering, working on this project have expose my knowledge to function and working principle of many electrics components such as voltage comparator, transistor, and mainly to auto-transformer. It has made me to understand the working principle and application of s of over and under voltage cutout if for both in homes and industries. 1.4

APPLICATIONS

OF

HIGH-AND-LOW

VOLTAGE

MONITOR

Over or under voltages in electricity is one of the major problems that affect their production. Due to high demand of electricity to sustain their operations, it results to low or high voltage output which can damage

equipments. Therefore, these companies need specialized devices to help them protect their equipments from early wear and tear. High-And-Low Voltage monitor is an electromechanical constituents that control the regular voltage outputs. During peak consumption of electricity, the sudden flow of power can damage electric or electronic machines. On the other hand, if there is low output of voltage, a machine may fail to function. It provide safe output to guard varieties of equipments including ultra modernized music systems, medical equipments LCD, Home Theater, industrial machines and more. They are designed with special features to protect equipments which include line noise spike protection, primary switching technology, auto reset, and overload cutoff protection. In order to preserve the life of machines, these devices are recommendable in any operation. They assure that machines are working well all the time especially in peak timings. 1.5

ADVANTAGES AND APPLICATIONS OF THE PROJECT 

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Cost is less as compared to voltage stabilizers Consumes less power. This circuit is used in homes and offices to protect equipments from high voltages and low voltages.

This material is a complete and well researched project material strictly for academic purposes, wh approved by different Lecturers from different higher institutions. We make abstract visible All Project Topics on this site have complete 5(five) Chapters . Each Project Material include: Abstract + etc + Literature Review + etc + Conclusion + Recommendation + References To

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Know about Under and Overvoltage Protection Circuit with Working by Tarun Agarwal at 

ELECTRONICS 8 COMMENTS

For the satisfactory working of all electrical and electronic devices,  it is recommended to allow voltage at prescribed limits. Voltage fluctuations in electric power supply certainly have adverse effects on connected loads. These fluctuations can be of over voltage and under voltages which are caused by several reasons like voltage surges, lightning, overload, etc. Over voltages are the voltages that exceed the normal or rated values which cause insulation damage to electrical appliances leading to short circuits. Similarly, under-voltage causes overloading of the equipment leading to lamp flickers and ineffici ent performance of the equipment. Thus, this article is intended to give under and overvoltage  protection circuit schemes with different control structures.

Over Voltage or Under Voltages

To understand this concept and know it better, one needs to go through three different types of over voltage protection circuits that use comparators and timers.

1. Under and Over Voltage Protection Circuit Using Comparators This voltage protection circuit is designed to develop a low-voltage and high-voltage tripping mechanism to protect a load from any damage. In many of the homes and industries fluctuations in AC mains supply take place frequently. The electronic devices get easily damaged due to fluctuations. To overcome this problem, we can implement a tripping mechanism of under / overvoltage protection circuit to protect the loads from the undue damage.

Overvoltage and Under Voltage Protection Block Diagram

Circuit Operation 

As shown in the above block diagram, the mains AC power supplies the power to the whole circuit and for operating loads by using relays, and also for tripping the load (lamps) in the presence of the input voltage which falls above or below a set value.

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Two comparators used as a window comparator formed out of one quad comparator IC. This operation delivers an error in the output if the input voltage to the comparator crosses the limit beyond the voltage window. In this circuit, an unregulated power supply is connected to bot h op-amps terminals, wherein each noninverting terminal is connected through the two series resistors and a potentiometer arrangement. Similarly, the inverting terminal is also powered through Zener diode and resistance arrangements, as shown in the given under or overvoltage protection circuit.

Overvoltage

Protection

Circuit using Comparators 

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The Potentiometer’s preset VR1 is adjusted such that the voltage at non -inverting is less than 6.8V for stable maintenance of load for the normal supply range of 180V-240V and the voltage of inverting terminal is 6.8V constant due to Zener diode. Hence the op-amp output is zero under this range and thus th e relay coil is de-energized and the load is not interrupted during this stable operation. When the voltage is beyond the 240 V the voltage at the non-inverting terminal is more than 6.8, so the operational amplifier output goes high. This output drives the transistor and thus the relay coil gets energized and finally loads are turned off due to overvoltage. Similarly, for under voltage protection, lower comparator energizes the relay when the supply voltage falls below 180 V by maintaining 6V at the inverting terminal. These under and overvoltage settings can be changed by varying the respective potentiometers.

2. Under and Over Voltage Protection Circuit using Timers This is another under / overvoltage protection circuit for designing low- voltage and high voltage protection mechanismto protect the load from damage. This simple electronics circuit uses timers in place of comparator as in the above case as a control mechanism.

These two timers combination delivers an error output to switch the relay mechanism when the voltage violates its prescribed limits. Thus, it protects the appliances from the adverse effects of supply voltage.

Over Voltage Protection using Timers

Circuit Operation: 

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The entire circuit is powered with rectified DC supply, but the regulated power is connected to timers and unregulated power is connected to potentiometers to get the variable voltage. Both the timers are configured to work as comparators i.e., as long as the input present at the pin2 of timer is less positive than 1/3 Vcc then the output at pin 3 goes high and reverse will happen once the input at pin2 is more positive than the 1/3 Vcc. The Potentiometer VR1 is connected to timer 1 for under voltage cutoff, and the VR2 is to second timer for over-voltage cutoff. The two transistors are connected to two timers for making switch logic.

Overvoltage Protection Circuit using Timers 

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In the normal operating conditions, (Between 160 and 250 V) the output of the timer 1 is held low so the transistor 1 is in cutoff state . As a result, the reset pin of the timer 2 is high which causes to output at pin 3 is high, so the transistor 2 conducts, and then the relay coil gets energized. Thus, in the normal or stable-voltage conditions the load doesn’t get interrupted. In the overvoltage condition (above 260V), the input voltage at pin 2 of timer 2 is goes high. This causes low output at the pin 3, which in turn drives the transistor 2 into a cutoff state mode. Then, the relay coil gets de-energized and the load gets tripped from the main supply. Similarly, in under voltage condition, the timer 1 output is high and it drives the transistor 1 into conduction mode. As a result, the reset pin of timer 2 is goes low and therefor the transistor 2 is in cutoff mode. And finally, the relay is getting operated to isolate the loads from the main supply. These overvoltage and under voltage conditions status are also displayed as LED indication which are connected to respective timers as shown in the figure.

These are the two different overvoltage and under-voltage prote ction circuits. Both circuits work in a similar way, but the components used makes the difference between them. These circuits are simple, low cost and easy to implement and therefore, now you will be able to choose between these two for the best and reliable control with ease of implementation. So write your choice and for any other technical help to  build electronic  projects circuits in the comment section below. Photo Credits:   

Over Voltage or Under Voltages by static Overvoltage Protection Circuit using Comparators by blogspot Overvoltage Protection Circuit using Timers by electronic-circuits

Mains Over Voltage and Under Voltage Protection Circuit Explained December 17, 2011 – by hitman97

The post discusses a mains 220V or 120V operated over voltage and under voltage protection circuit using relay cut-off, and using just a couple of transistors.

Our Mains AC domestic power may be full of ups and downs or fluctuations, which may be quite fatal to our sophisticated appliances like TV sets, DVD players, compotes etc. A very simple circuit presented when installed in the house electrical may help in restricting the issue to a great extent.

Here we will learn two designs of over and under voltage circuits, the first based on transistors and the other one using an op amp.

Using Transistors:

You will be surprised to know that a nice little circuit for the said protections can be built using just a couple of transistors and a few other passive components.

Looking at the figure we can see a very simple arrangement where T1 and T2 are fixed as an inverter configuration, meaning T2 responds oppositely to T1.

Please refer the circuit diagram.

In simple words when T1 conducts, T2 switches OFF and vice versa.

The sensing voltage which is derived from the DC supply voltage itself is fed to the base of T1 via preset P1. The preset is used so that the tripping thresholds can be determined precisely and the circuit understands when to execute the control actions. P1 is set for detecting high voltage limits.

Initially when the voltage is within the safe window, T1 remains switched OFF and this allows the required biasing voltage to pass through P2 and reach T2, keeping it switched ON.

Therefore the relay is also kept activated and the connected load receives the required AC voltage.

However in case suppose, the mains voltage exceeds the safe limit, the sensing sample voltage at the base of T1 also rises above the set threshold, T1 immediately conducts and grounds the base of T2.

This results in switching OFF of T2 and also the relay and the corresponding load. The system thus restricts the dangerous voltage from reaching the load and safeguards it as expected from it.

Now suppose the mains voltage goes too low, T1 is already switched OFF and at this situation T2 also stops conducting due to the settings of P2, which is set so that T2 stops conducting when the Mains input goes below a certain unsafe level.

Thus the relay is once again tripped OFF, cutting of power to the load and prompting the required safety measures.

Though the circuit is reasonably accurate, the window threshold is too wide, meaning the circuit triggers only for voltage levels above 260V and below 200V, or above 130V and below 100 V for 120 V normal supply inputs.

Therefore, the circuit may not be very useful for folks who might be looking for absolutely accurate tripping points and controls which can be optimized as per ones personal preference.

To make this possible a couple of op amps may be required to be included instead of transistors.

Parts List for the above AC mains over voltage, under voltage protection circuit.

R1, R2 = 1K,

P1, P2 = 10K,

T1, T2 = BC547B,

C1 = 220uF/25V

RELAY = 12V, 400 OHMS, SPDT,

D1 = 1N4007

TR1 = 0-12V, 500mA

Using an Op Amp:

The above discussed operations can also be done using an op amp, with precise results.

Overvoltage and Under Voltage Protection System March 6, 2017 by Tarun Agarwal 4 Comments

If any unexpected fluctuation in the power supply may cause many problems in the industries, homes, offices. Voltage fluctuations in the electric power supply have a very poor effect on connected load. These fluctuations of over voltage and under voltage protection system are produced by many reasons which are like voltage surges, limiting, overload and etc. General applications of these systems are used in agriculture motors, water pumps and etc. In this article, we will discuss the different control structures like timers and comparators of the under voltage and over voltage protection system.

What is an Over Voltage and Under Voltage Protection? In the following characteristics, the voltage exceeds its upper limit is called as over voltage. Depending on the duration the over voltage durations are like a transient, voltage spike and power surge. The following graph shows the variations between the time and voltage. When the voltage is below the fixed voltage is said to be as under voltage.

Over Voltage Protection

Over Voltage and Under Voltage Circuit Using Comparator

The components required for the block diagram of the comparator circuit is the power supply, step down transformer, bridge rectifier, two preset pins, comparators, voltage regulator, relay, buzzer and AC current. This circuit is planned to expand a low voltage and high voltage tripping mechanism to protect the load from the damage. Generally, in homes & industries, we can observe that there is a fluctuation in AC power supply takes place frequently. Due to the fluctuations of the AC power supply, the electronic gadgets will damage easily. To overcome this problem we can implement the tripping mechanism of over voltage and under voltage protection circuit.

Block Diagram of Over Voltage and Under Voltage Circuit Using Comparator

Circuit Diagram Operation The circuit diagram consists of two IC which are named as LM324, LM7812, NPN transistor, two Zenor diodes, capacitors and LED respectively. In the circuit, we can observe that the input of 220v AC through a transformer T1 and it reduce up to 12v with the help of the bridge rectifier. By using the two capacitors C1 & C2 of power smoothing filters we can convert the voltage, alternating current to direct current.

Circuit of Over Voltage and Under Voltage Protection Using A Comparator

The IC Rex bit is an input pin of IC1 is computing to the 12v power supply is fixed to the IC2. Thus we can consider as an IC op-amp and its pressure act as an IC2/1 is a high voltage detector, high voltage ICs, current works to the transistor Q1 and the relay function works with the cutting of power from the load intensity. The IC/2 is used to detect the lower voltages and with VR1 & VR2 the two components are specified. The LED is used to display the high power & low power over a specified.

Over Voltage & Under Voltage Protection System Using Timer This is another type of protection system using timer circuit is designed for the low voltage & high voltage protection system load from the damage. From the above circuit, we can observe that in the place of comparator we are using a timer in this circuit. These two timers are delivered an output error to switch the relay mechanism when the voltage violates its arranged limits. Therefore it protects the appliances from the adverse effects of the supply voltage.

Block Diagram of Over Voltage & Under Voltage Protection System Using Timer

Circuit Diagram Operation The entire power supply of this circuit is in rectified DC supply and to get the variable voltage the regulated power is connected to the timers & unregulated power is connected to the potentiometer. The two timers configurations are working as a comparator i.e., the input is at the timer to the pin 2, it is less positive than the 1/3 Vcc. The output pin is at the pin 3 which goes high and once the input pin 2 is more positive than the 1/3 Vcc it will be reversed. The potentiometer VR1 is connected to the first timer for under voltage cutoff, the potentiometer VR2 is connected to the second timer for over voltage cutoff.

For the formation of switch logic, the two transistors are connected to the two timers. Generally, we consider that normal operating conditions are between 160 to 250V at this voltage the output of the first timer is considered as a low, thus  the transistor 1 is in the cutoff state. Therefore the result will be the reset pin of the second timer is at high which produces the output at pin 3 is high. So that the transistor 2 is in the conducting state and the relay coils are energized. Hence, in the normal conditions, the load will not get interrupted.

Circuit Diagram of Over Voltage and Under Voltage Protection System Using Timer

In the over voltage conditions are considered about above the 260V at this condition the second timer pin 2 will be high. It produces the low output at the pin 3, therefore the drivers turn the second transistor into the cutoff mode. Thus, the relay coils are de-energized from the main power supply the load gets tripped. In the same way, in the under voltage conditions, the first timer output is high and drives the first transistor mode in the conduction state. Therefore the reset pin of the second timer is at the low condition and the second transistor is in the cutoff mode. Finally, the relay is operated to isolate the load from the main power supply. The conditions of the over voltage and under voltage positions are also displayed on the LED indication which is connected to the respective timers are shown in the figure.

 Application of Over Voltage and Under Voltage    

It is used in the home appliances, industries to control the voltage fluctuations Protection of sensitive electronic devices  Agriculture motors Water pumps

 Advantages of Over Voltage and Under Voltage     

The price of this circuit is very less and r eliable It can handle heavy loads up to 7A In the abnormal condition automatically the switch is OFF state In the safe condition automatically the switch is in the ON-state These are highly sensitive

In this article, we have discussed the over voltage and under voltage protection system. I hope by reading this article you have gained some basic information about this article. If you have any queries about this article or about the implement ation of the major projects in electrical & electronic please feel free to comment in the below section. Here is the question for you, what is the function of over voltage and under voltage protection system? Filed Under: Electrical, Electronics