shunt trip breakers

[reskra]

Shunt trip breakers supplied with radiology equipment are tripping everytime the generator is tested in a hospital and have to be manually reset. Does anyone know what would cause this?

 

[coulter]

Is it the shunt trip that is activating or is it a CB protective relay that 's tripping?

carl

 

[infinity]

Does it trip if the building switches from normal to EM (Gen) power?

 

[tallgirl]

Shunt trip breakers supplied with radiology equipment are tripping everytime the generator is tested in a hospital and have to be manually reset. Does anyone know what would cause this?

Where are the cables for the shunt trip part being routed? Do they hang out around anything that might not be energized when the generator is tested?

 

[iwire]

Assuming it is not the shunt causing it but the instantaneous trip unit that is casing this I would recommend changing the transfer switch programing to delayed transition.

What this does (if the ATS has the feature) is disconnect the load from one source then it waits for however long you program it for before reconnecting to the other source.

A quick transfer from one active source to another can cause breaker tripping. I believe the delay lets any supplied transformers or motors completely go dead before being energized again.

Any way adding a 1 second delay has worked for me in the past when customers had seeming random breaker tripping with transfer switch operation.

 

[brian john]

Or is this an undervoltage release..seen this more than once on ATS transfer....

Check the "shunt trip" (cause it may not be a shunt trip) for voltage when operating normally.