Design and fabrication of over voltage relay
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This document describes the design and fabrication of an over voltage relay to be integrated into a power system lab. It presents the circuit design which uses a transformer, rectifier, regulators, op-amp, resistors, capacitors, diode, potentiometer, and relay. The over voltage relay works by comparing the input voltage to a reference voltage using an op-amp circuit. If the input voltage is higher than the reference voltage, the relay will trip to protect equipment from overvoltage.
Design and fabrication of over voltage relay
- 1. DESIGN AND FABRICATION OF OVER VOLTAGE RELAY TO BE INTEGRATED IN POWER SYSTEM LAB Presented by: PREMCHAND KUMAR :-120301ELR055
- 2. CONTENTS INTRODUCTION CAUSE OF OVER VOLTAGE EFFECTS OF OVER VOLTAGES CIRCUIT DESIGN COMPONENT REQUIRED Working Principal CONCLUSION
- 3. INTRODUCTION OVER VOLTAGE:- When the voltage in a circuit or part of it is raised above its upper design limit, this is known as overvoltage.
- 4. CAUSE OF OVER VOLTAGE Overvoltage can be caused by a number of reasons, sudden reduction in loads switching of transient loads lightning strikes failure of control equipment such as voltage regulators neutral displacement.
- 5. EFFECTS OF OVER VOLTAGES ON POWER SYSTEMS: Over voltage tends to stress the insulation of the electrical equipment’s and likely to cause damage to them when it frequently occurs Over voltage caused by surges can result in spark over and flash over between phase and ground at the weakest point in the network, breakdown of gaseous/solid/ liquid insulation, failure of transformers and rotating machines.
- 7. Components Required • Transformer 12v • Bridge wave rectifier • Capacitors-1000micro farads 63v & 1 micro farad 25v • Regulator 7812 , 7912 • Potentiometer-10k • Resistances -10k,1k • IC LM741 • Led • Diode of IN4007 • Relay • Load
- 8. COMPONENT DESCRIPTION TRANSFORMER:- A transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. It is use for step down the voltage from 220v to 12v
- 9. CAPACITOR Here the capacitors are used for filtering purpose.
- 10. Regulator 7812 , 7912 Here is circuit Power Regulator +12V,-12V. IC LM7812 is used for +12V and IC LM7912 is used for -12V.
- 11. Potentiometer-10k Potentiometer also known as pot is generally used in circuits to provide variable resistance or variable voltage.
- 12. OP-AMP The Operational Amplifier is probably the most versatile Integrated Circuit available. The most common Op-Amp is the 741 and it is used in many circuits. The OP-AMP has two inputs, INVERTING ( - ) and NON-INVERTING (+), and one output at pin 6.
- 13. PIN DESCRIPTION OF IC LM741
- 14. WORKING OF OP-AMP 741: INVERTING AMPLIFIER:- NON-INVERTING AMPLIFIER:
- 15. COMPARATOR:
- 16. Diode(IN4007) Diodes are frequently used to conduct damaging high voltages away from sensitive electronic devices. A diode offers a very low resistance in one direction and a very high resistance in other direction, thus permitting an easy current flow in only one direction.
- 17. Relay A relay is an electromechanical device that is actuated by an electrical current. The current flowing in one circuit causes the opening or closing of another circuit. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to protect electrical circuits from overload or faults.
- 18. Working Principal:- We are giving 220 volts ac as a input to the transformer. We are using step down transformer it serves to reduce the pressure remaining 12 volts, through a D1-D4 connected to direct rectifier bridge circuit. This rectifier converts ac to dc but the obtained dc is not pure dc it is a pulsating dc, to obtain pure dc we are using regulator (IC LM7812 & 7912) .
- 19. continue…. From IC LM 7812 we obtained +12v & from IC LM7912 -12v. Here the capacitors are used for filtering purpose. The output of 7812 & 7912 regulator is connected to OPAMP 741.It compares two input voltages one voltage is reference voltage (Vref) and the other is called the input voltage (Vin).Whenever the Vin rises or falls below the Vref value the polarity of the output changes thus making it to work as a comparator.
- 20. continue…. If the Vin will be greater then Vref then relay will trip .Thus we can protect our equipment from overvoltage.
- 21. CONCLUSION: It will indicate the high voltage. Due to this we can safe guard our home appliances without damaging the equipments.