Switchgear with Shunt trip

[Brownetown]

I have an old switchgear most likely 30years+. It has a shunt trip device tied in with Handel. Every time customer loses power something triggers the Gear to trip.

Problem the ats is tied in after switch gear. Everytime they lose power ATS switches over but never realizes power has been restored due to the gear always going into trip position.

I’ve located an old phase monitor along with a re-set button. I’ve did a little digging and saw that this was a normal years ago having the phase monitor trigger the shunt due to has anyone have experience with this?

 

[jim dungar]

...this was a normal years ago having the phase monitor trigger the shunt due to has anyone have experience ...

I wouldn't say it was normal, but it was not uncommon where a facility running at low voltage or reverse phasing was more of a problem than having no power at all.

There should be no problem with you simply disconnecting the phase monitor from the breaker. But you would want to make sure the breaker actually has a shunt trip and not an under voltage trip.

 

[Jraef]

I just have to comment on “…old switchgear most likely 30years+.”

What???

But also, is it a shunt trip or an under voltage trip? It sounds like an under voltage trip.

 

[DBill64]

I mean it sounds like they did one of two things:

Designed it specifically for the shunt trip to trigger due to power issues, the ATS would then supply power for the duration of power loss, but intentionally made it so that reinitialization of normal power had to be done manually (probably as a way to ensure people put eyes on equipment in the facility before reinitializing normal power?).
OR
They goofed up when designing the ATS addition sometime after the original install of the switchgear, and did not take into account the existing power monitoring and shunt trip breaker.

How long do these power outages usually last? Are these short fraction-of-a-second blips or hour-long outages? If they're short, you could look to add a time delay to the input of the shunt trip (of like 1-3 seconds) to eliminate nuisance tripping from short lived power outages.

You could also just disconnect the phase monitor from the shunt trip like Jim said, but I would make absolutely sure that it is 100% no longer required before doing that. The original design wasn't done for no reason. Someone deemed it pretty critical to make sure that normal power was disconnected if that phase monitor saw something it didn't like.

 

[hillbilly1]

I have an old switchgear most likely 30years+. It has a shunt trip device tied in with Handel. Every time customer loses power something triggers the Gear to trip.

Problem the ats is tied in after switch gear. Everytime they lose power ATS switches over but never realizes power has been restored due to the gear always going into trip position.

I’ve located an old phase monitor along with a re-set button. I’ve did a little digging and saw that this was a normal years ago having the phase monitor trigger the shunt due to has anyone have experience with this?

There is a high rise in downtown Atlanta that has that, no generator though. Building was built probably in the 70’s. It was to protect against single phasing, which is probably what’s happening to your building. Poco loses one phase, instead of all three. Do they have a fire pump? Lowes drops the generator feed to the building if the fire pump starts. They had an issue with the shunt trip on the generator firing due the momentary power outage to the fire pump. A lot of fire pump controllers fail to the “ON” position momentarily. I had the manufacturer add a short time delay to the contact to prevent nuisance tripping.