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How can I design a system that gives the functionality of an MCB (overload protection, operates in an AC circuit) with an electronic trigger-off.

So that once the device is in ON state, it should be able to be turned-off by

  1. Human interaction (mechanically flipping the latch)

  2. Over-load (MCB inherent feature)

  3. Electronically, by using a small trigger voltage. Once this trigger is applied this switch should be mechanically flipped to off position, so that the user should see it is in OFF state.

The device is to be used to run a domestic motor (say 1HP.)

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closed as too broad by RoyC, Finbarr, stefandz, evildemonic, Lior Bilia May 16 at 19:34

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ It sounds like you want to purchase a device for this purpose. This site is specifically for the design of electronic circuits, so we don't like to recommend specific products. Such recommendations rarely have lasting value, and we want to avoid any product promotion as well. \$\endgroup\$ – Elliot Alderson Apr 17 at 14:05
  • \$\begingroup\$ Did you not search for "Remotely Operated Circuit Breakers"? There's plenty of results. \$\endgroup\$ – Phil G Apr 17 at 15:01
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    \$\begingroup\$ In molded case circuit breakers, there are shunt-trip breakers that are tripped by energizing a solenoid inside the circuit breaker. They may also have other names. That feature may not me available in miniature circuit breakers. \$\endgroup\$ – Charles Cowie Apr 17 at 16:11
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schematic

simulate this circuit – Schematic created using CircuitLab

Figure 1. RCD/ELCB/GFCI and relay.

  1. Human interaction (mechanically flipping the latch)

Toggle the RCD switch.

  1. Over-load (MCB inherent feature)

Built in on the RCD.

3.Electronically, by using a small trigger voltage. Once this trigger is applied this switch should be mechanically flipped to off position, so that the user should see it is in OFF state.

  • Use a relay to switch in a resistance to unbalance the RCD/ELCB/GFCI1.
  • When R1 and R2 are switched in there will be more current passing through the live pole of the RCD than is returning on the neutral pole.
  • On 230 V systems 4.4 kΩ will result in 50 mA difference and this should trip a 30 mA RCD. On 120 V systems R2 may be omitted.

The device is to be used to run a domestic motor (say 1 HP).

You omitted the voltage so we don't know what current this is likely to be so you'll need to work that out.


  • RCD = residual current device.
  • ELCB = earth leakage circuit breaker.
  • GFCI = ground-fault circuit interrupter.

They're all pretty much the same.

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  • \$\begingroup\$ The house may be protected by another RCD, which means this system will sitting inside another RCD. While we imbalance the RCD will the main RCB also get triggered. \$\endgroup\$ – user2332665 Apr 20 at 3:08
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    \$\begingroup\$ That could be a problem. In some countries only the power sockets are on RCD so that the house lights, etc., remain on in the event of a trip. (No point in saving someone's life with an RCD and then kill them falling down the stairs going to the fuse box in the dark.) Check your installation to see. I offered the solution as a novel way of achieving your requirements. \$\endgroup\$ – Transistor Apr 20 at 7:59

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