The project is designed to shut down
the power supply when it is overloaded. Conventional circuit breaker like MCB
based is on thermal bimetal lever trip mechanism. It is very slow and the trip
time is dependent upon the percentage of overload. This project senses the
current passing through a series element and the corresponding voltage drop is
compared against the preset voltage proportional to the current by a level
comparator to generate an output for the load to trip.
The concept of electronic circuit
breaker came into focus realizing that conventional circuit breakers such as
MCBs take longer time to trip. Therefore, for sensitive loads it is very
important to activate the tripping mechanism at the shortest possible time,
preferably instantaneously. This project is demonstrates fast tripping
mechanism as against the slow one like MCB. Electronic circuit breaker is based
on the voltage drop across a series element proportional to the load current,
typically a low value resistor. This voltage is sensed and rectified to DC
which is and then compared with a preset voltage by a level comparator to
generate an output that drives a relay through a MOSFET to trip the load. The
unit is extremely fast and overcomes the drawback of the thermal type. It uses
a microcontroller from 8051 family.
Further the project can be enhanced
by using a CT for galvanic isolation between mains and control circuit. Power
electronic devices such as thyristors / IGBTs can be used for ultra fast
operation compared to all the methods.
Hardware Requirements:
8051 series Microcontroller, Op-amp,
Transformer, MOSFET, Diodes, Capacitors, Resistors, LED, Crystal, LCD, Voltage
Regulator, Relay, Lamps.
Software Requirements:
Keil compiler
Languages: Embedded C or Assembly