Three Trip Solenoids 1

[Mbrooke]

Anyone know of a case where a common trip pole breaker would have 3 trip solenoids?

 

[thermionic1]

Likely the mounting bracket for the trip coils is reused for other purposes, such as the close mounting bracket (and other things).

 

[Mbrooke]

Well...

 

[The_Other]

Two protection trips and point of wave relay open.

 

[Mbrooke]

Thanks. Would there be any reason why point on wave switching can't use the other two solenoids?

 

[jwatty]

Point on wave tripping means you'll have separate trip commands for each phase; You certainly can have this set of coils operated by protection and point-on-wave control, but you either have to use a bunch of diodes or you'll need to have protection have three separate trip outputs (one per phase).

 

[The_Other]

It is possible to use a mechanically staggered three pole operated circuit breaker for point on wave opening of a reactor, however not ideal as the same circuit breaker can't be used for point on wave closing.
For a three pole operated CB you most likely would use one of the other solenoids.
I believe Siemens use the same mechanism across their spring operated breakers, which is why there is space for a third solenoid even when not required.

 

[RRaghunath]

Could it be that the space for third coil is not for Trip coil but for No-volt release??
I have seen vendors offering to tri coils plus one no-volt (or Under Volt) release.
Three trip coils makes sense only if the operating mechanism can be single phase. This is a standard option at 132kV and above in case the client is looking for the option of single phase reclose as part of Auto reclose philosophy for the transmission lines.

 

[Mbrooke]

@The_Other: that makes a lot of sense in that you would trip all of the individual poles simultaneously with each trip coil 1 and 2 for regular fault trip, while number 3 would be independent for point on wave switching. Do I have it right?

Yes, this is a diagram for a Siemens breaker. I once drew up a 3x redundant DC system for the fun of it- this was one of those "oh, thanks, you make it to easy!"

 

[The_Other]

Yes, that is correct for a single pole operated circuit breaker.
We run one trip wire out from the control building to the circuit breaker from each protection. This is then jumpered to the trip solenoid for each phase.
We run three open wires from the point on wave relay to the circuit breaker, one for each phase.

 

[Mbrooke]

Makes sense now, thanks!