Switch gear for Dual Transformers

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james wuebker

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Location
Iowa
We are pouring 2 transformer pads for a big plastic molding company. The electric company is going to install 2- 2500KVA transformers there. I believe there's going to be 1- 4000 amp GFCI disconnect for each. Do there make switch gear that big so if one transformer quits we can switch over and use one transformer to run it all until we can get the other transformer on line?
 
Re: Switch gear for Dual Transformers

You can use double ended switchgear with a tie breaker. Just be aware of the ground fault circuitry problems and the increased available short circuit current if the plant is operated with both services and the tie breaker closed. Load may also have to be shed to get under the capacity of a single transformer when operating off only one.
 
Re: Switch gear for Dual Transformers

As mentioned they are called double ended, or main-tie-main (or for that matter main-tie-tie-main also). If it is a manual operation, then loads can be shed at that time. It can be designed as an automatic transition (open or closed type).
 
Re: Switch gear for Dual Transformers

You do not mention the secondary voltage of the transformer, or the type and rating of the transformer. Bottom line is you need to know the low voltage side max. amps. This should be on the transformer nameplate.

Assuming the secondary side is 480 volts, your switchgear would have a main breaker for each transformer and a normally open tie breaker.
The largest standard size bus would be 4000 amps.

This is basic reply. would need more details. Liquid filled transformer ( assumed if it is out doors.) Type rating Delta / Wye , OA / FA etc.
 
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