enter image description hereI want trip a MCB whenever I want to trip using some ckt.I have found that there is two mechanism by which mcb trip: 1)Bi Metallica expansion 2)Solenoid effect. So i think of controlling the solenoid by some external connection.But till now nothing works. Plz give a way so that i can do it.

  • \$\begingroup\$ Can you also add purpose too. People can suggest safer ways. \$\endgroup\$
    – User323693
    Feb 15, 2017 at 14:18
  • \$\begingroup\$ Let me paraphrase your question: You want to add a remote controlled switch functionality to your circuit breaker which is not tied to overcurrent or other means of overload? \$\endgroup\$
    – Ariser
    Feb 15, 2017 at 15:03
  • \$\begingroup\$ Yes want a push button outside the MCB to trip it.My plan is to take out the connection of Solenoid(inside MCB) and using a rectifier ckt to control it.But thats not working. \$\endgroup\$
    – jintu bora
    Feb 16, 2017 at 16:01

1 Answer 1


Anything that you do to the inside of the circuit breaker will either jeopardize or destroy at least some of the normal function of the MCB. Even just opening the case makes the future function of the MCB questionable.

You could conceivably use an external solenoid to push the lever.

You could connect a relay in series with the circuit breaker.

You could buy a circuit breaker with a built-in shunt-trip mechanism, but that would be a molded case circuit breaker that would be larger and more expensive.

can you plz provide a circuit of "shunt trip coil"?

The trip coil shown in the picture could be converted to a shunt trip coil by disconnecting it and providing a new path for current through the thermal trip element. Then the 5 turns of heavy wire would need to be removed and replaced with many more turns of smaller wire. It you want to trip the breaker by supplying 2% of the present magnetic trip current, you would divide the original number of turns by 0.02 and use about 250 turns. The trip current multiplied by the number of turns needs to remain about the same.

  • \$\begingroup\$ can you plz provide a circuit of "shunt trip coil"? \$\endgroup\$
    – jintu bora
    Feb 26, 2017 at 14:38

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