Electronics November 1, 2021


by kazawadi

Electric devices such as motors and lamps get faults because of overvoltage or undervoltage. Which is the most cause by fluctuation to the AC mains. This causes disturbances to the electricians to use most of the time for maintenance per day.

Therefore due to this problem, the designing of overvoltage and under voltage detection system will solve the problem


To protect the electric devices from damage due to overvoltage
or under voltage

Increase the production at the company

Remove disturbances of daily maintenance


The existing system has some downs in protecting the electric devices from overvoltage and under voltage.


It leads to the damage of electric devices due to the failure in controlling the rise and falling of voltage.

  • The system will include AC power supply , transformer, bridge rectifier, regulator, microcontroller, relay, display and load.
  • The proposed system will protect the electric devices from being damaged due to over and under voltage
  • Reduce the disturbances of daily maintenance to the electricians¬†
  • Increase the production at the company

The circuit is provided with AC voltage as an input to the transformer. Then the step down transformer used to step down the voltage and connected direct to the bridge rectifier circuit.

This rectifier converts AC to DC but the obtained DC is not pure DC it is pulsating DC to obtain pure DC. We are using the capacitors for filtering and voltage regulator for keeping a constant output DC voltage for powering the microcontroller and display.

The variation of voltage obtained by varying the value of the potentiometers inserted after the capacitors. To the potentiometer is where we insert the reference values for both overvoltage and under voltage.

The microcontroller then play part in comparing the two voltages the coming voltage with the required voltage basing to the reference value of voltage.

When the coming voltage is beyond the reference voltage then the microcontroller sends signals to the transistors to trigger the relay to cut the supply. When fluctuations occur the transistor triggers the relay coil to de-energize there by cutting supply to the load.

At normal condition it triggers the relay coil to re-energize so as to power the load.

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