Standby/Emergency Gen Sets

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Lady Engineer

Senior Member
Location
New Jersey
Ok, I have a 600KW Gen Set. The ATS, rated 800A, is connected to the Gen Set, the Normal is connected to a 800A air breaker (branch) in Main Switchgear (rated 4000A) and the Load side of the ATS goes to an 800A EM. Panel. The Panel does not feed Life Safety loads. The main for the switchgear is rated 3000A at 480V.

Question: I don't want to install a 3000A ATS, but I would like to feed the entire building off of the 600KW Gen Set, by load shedding done to the loads which need back up. Is there a way I can do this on the load side or line side of the 3000A Main with using the 800A ATS?? The reason I want to feed the building is that, the current life safety loads are on batteries so they aren't separated into separate panels or circuits. :?
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
Ok, I have a 600KW Gen Set. The ATS, rated 800A, is connected to the Gen Set, the Normal is connected to a 800A air breaker (branch) in Main Switchgear (rated 4000A) and the Load side of the ATS goes to an 800A EM. Panel. The Panel does not feed Life Safety loads. The main for the switchgear is rated 3000A at 480V.

Question: I don't want to install a 3000A ATS, but I would like to feed the entire building off of the 600KW Gen Set, by load shedding done to the loads which need back up. Is there a way I can do this on the load side or line side of the 3000A Main with using the 800A ATS?? The reason I want to feed the building is that, the current life safety loads are on batteries so they aren't separated into separate panels or circuits. :?
No way around getting a 3000 amp switch as when on normal power there is no load shed and it has to carry the entire potential 3000 amp load. Otherwise it sounds like a sound plan. I'm assuming this is an optional standby system then.
 

Lady Engineer

Senior Member
Location
New Jersey
No way around getting a 3000 amp switch as when on normal power there is no load shed and it has to carry the entire potential 3000 amp load. Otherwise it sounds like a sound plan. I'm assuming this is an optional standby system then.
I didn't think so either. Thy person before me didn't think about. It seemed hokey to me.
 

iwire

Moderator
Staff member
Location
Massachusetts
Kirk keys and breakers with an external control.

We just completed a supper market where a generator is set up to run the entire switch board by back feeding the gear through a generator breaker interlocked with the main.

So you could have a 2000 amp main, interlocked with a 600 amp generator breaker avoiding a full sized transfer switch.
 

Lady Engineer

Senior Member
Location
New Jersey
Kirk keys and breakers with an external control.

We just completed a supper market where a generator is set up to run the entire switch board by back feeding the gear through a generator breaker interlocked with the main.

So you could have a 2000 amp main, interlocked with a 600 amp generator breaker avoiding a full sized transfer switch.
Trying to find out what to do with the 800A ATS. It's fairly new, about 3 years old.
 

dkidd

Senior Member
Location
here
Occupation
PE
I once had a client who bought a generator on eBay and wanted to use it. Problem was it was 120/240 single phase and he needed 480Y/277.
 

MSU

Member
Location
Hattiesburg, MS
Verify MCB open

Verify MCB open

If using the Kirk Key scheme, the only thing you know when you "open" the main CB is that the handle moved. If possible, devise a scheme to prove contact separation. Otherwise backfeeding the Utility will be the result.
 

texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
A Kirk key system would be OK, but I was under the impression that even though this is an optional standby system, it was to be automatic. If you want to go the manual/Kirk key route, GE and others make a pre packaged set up for this.
 
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