Square D breaker tripping

[Electron_Sam78]

I have a Square D Powerpact MJP36600 600 amp breaker that kept tripping with loaded or unloaded and with or without power. Upon dissecting the breaker, It turns out that the actuator/solenoid was tripping it due to continuous spring tension from the solenoid applied to the tripping mechanism. Does anyone know how the internals are supposed to work? It seems that the solenoid should have reverse spring tension keeping it in and that the trip unit should fire it upon a trip sense. I ended up removing the solenoid to get the panel back in service due to the high priority the fed equipment had and it is protected upstream at the switchgear. Picture of the solenoid attached.

 

[jim dungar]

Was this breaker provided with the optional undervoltage release?
You would have to ask the system designer why this was chosen, there may be good reasons for it.

 

[Electron_Sam78]

Was this breaker provided with the optional undervoltage release?
You would have to ask the system designer why this was chosen, there may be good reasons for it.

Good question. I’m not sure

 

[hillbilly1]

Does this breaker have a shunt trip input?

 

[Electron_Sam78]

Does this breaker have a shunt trip input?

Does this breaker have a shunt trip input?

No

 

[jim dungar]

Does this breaker have a shunt trip input?

Shunt trips require a voltage be applied in order to cause a trip. The OP describes an under voltage release where a lack of applied voltage causes a trip.

The OP picture looks like a field replaceable module some body added it on purpose.

 

[hillbilly1]

Shunt trips require a voltage be applied in order to cause a trip. The OP describes an under voltage release where a lack of applied voltage causes a trip.

The OP picture looks like a field replaceable module some body added it on purpose.

Shunt trips can have an alternate power source, the breaker does not need to have power to trip.

 

[Jraef]

Shunt trips require a voltage be applied in order to cause a trip. The OP describes an under voltage release where a lack of applied voltage causes a trip.

The OP picture looks like a field replaceable module some body added it on purpose.

That's the first thing that came to mind for me too. The breaker may not have been ordered with a UV trip, but someone may have added one in the field.