Circuit Breaker in Switchgear Panels

You can connect all the trip commands in parallel and activate one trip coil. if your application demands additional trip coil to improve the reliability, contact the manufacturer. Additional trip coil can be mounted on the breaker upon ordering.

for the reliablity pupose you can use AC & DC trip coil . which is depends upon the user.

Strange thing is you'll find a lot of manufacturers will fit rectifiers to AC trip circuits and use DC coils.

why only one trip coil in switchgear panels is present in their circuit breaker??

(1) There are many switchboards with one main incomer CB and many outgoing CBs. Each CB will have its own protection scheme, depending on the kind of discrimination system preferred.

(2) There are mainly three kinds of trip coils: Shunt trip coils and undervoltage releases, and the trip coil of the protective relay if it is built into the CB. The trend nowadays is to use microprocessor based relays with their own low-energy trip coil (self-powered and not dependent on aux power). In most CBs, all three are provided in my experience.

However, as pravinba says, one can parallel all trip commands and use one coil only. Makes one dependant on aux supply.

DC is generally used since in critical power stations, battery banks are provided for reliable aux supply.

Elementary, Dr. Watson! Economy! There is nothing wrong in going for 100% redundancy, in breaker trip coils, if the application is critical. I have come across two trip coils PER POLE in all EHT Circuit Breakers that I have commissioned. The trip supplies, the cables, the cable routes - all will be seperate & different.