how to trip a circiut breaker with a pic micro

Hello,

If I understand your question correctly, you can purchase a circuit breaker with a shunt trip option. This allows an external signal to trip the circuit breaker. I know you can get them in AC version but I'm not sure about DC. Probably. I used Carling but Airpax may have them as well.

Tim

To add to the above post, most MCB manufacturers also sell shunt trips as add-ons to the MCB.

In the case of the GE brand (not wanting to plug GE here, but this is the brand that I am most familiar with), shunt trips are available that will fit both the MCBs and all of the RCCBs and RCBOs, and in two voltage ranges : AC 24V-60V/DC 24V-48V, and AC 110V-415V/DC 110-125V.

Clearly, to operate these with a PIC micro you will need an interface - either a small relay, or if you go with the lower DC option you could use a simple BJT or mosfet circuit.

In the real world you are going to need something that can auto reset after you enter a code from say a pre-paid electric card.. This means a shunt trip breaker will not work since it must be manually reset..

What you need is a contactor using as you suggested a relay that connects and disconnects the load.. The only type of breaker you could open and close without manual reset is of the industrial type which would not be cost efficient for residential customers..

Ah, mission creep.

If you really want to automatically reset your MCB (assuming that you do need to use an MCB instead of a contactor) then you can also buy a motor operator to do this.

This obviously adds to the cost, and Ekiechle is probably correct in that a contactor is almost certainly going to be the most economical option.

You don't say WHY you want to also trip the circuit breaker. A shunt trip option is a possible solution (although you are going to need to manually reset it).

Have you considered implementing a crowbar protection circuit? Effectively it means shorting out the output (with a low resistance load) which will trip the circuit breaker. The trick is to choose a load that will trip the circuit breaker without dissipating too much heat and of course tripping your circuit breaker before any of the downstream fuses or circuit breakers. A little dangerous if you don't know what you are doing.

Thinking about it you would be better off to just use a contactor in series with the circuit breaker and just use the contactor to disconnect the load.

Circuit breakers are not designed to be used as switches, they are protective devices. if you wear them out by operating them too much, they are a LOT more expensive to replace than contactors. You want a contactor.

The SY027 TRIP is used to monitor a 4-20mA loop and provides easily settable high and low level alarm relays. In order to prevent relay chatter at the set points Hysteresis of 0.4mA is included and LED's are provided to indicate a trip condition. Supply voltage for the trip amplifier is 24Vdc. Might help