Reverse-feeding this transformer

[Cannonmn]

Here's the label with diagrams:

 

[infinity]

OK what's the question?

Welcome to the Forum.

 

[ggunn]

Here's the label with diagrams:

Sometimes you can use a step up transformer as a step down (or vice versa) and sometimes you can't. Check with the manufacturer.

 

[GoldDigger]

This is a delta to delta to wye step down.
If you use it for step up you will end up with either ungrounded or corner grounded delta. Is that OK?

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[roger]

Here's the label with diagrams:

And a nice label it is.

Roger

 

[augie47]

Here is a interesting read from GE on the subject:
http://apps.geindustrial.com/publibrary/checkout/Transformer2?TNR=White Papers|Transformer2|generic

 

[Cannonmn]

Will this transformer work ok when reverse-fed to get 480/3?

Will this transformer work ok when reverse-fed to get 480/3?

Data in pic below. I need to create 480v.3phase to run machine tools. I have a qualified electrician ready to hook up transformer but he's not a transformer expert so I want to find out about issues in doing this. I know influx current will be momentarily high and we're prepared to deal with that. Big question I tried to get GE customer service to answer was whether this transformer, given where taps are etc., will present any huge problems. The GE instruction cited on the label pictured, only mentions the high influx current issue, but nowhere says you cant reverse-feed it. Then there's the ground issue. The only way I've read that you can create a ground for your loads is to use a corner ground, typically done by grounding the B phase. Comments?

 

[GoldDigger]

The only simple grounding solution for a delta is the corner ground.
Motors should have no problems with it, but some VFDs or built-in speed controls will not like it and at a minimum may need modification.

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[ActionDave]

Data in pic below. I need to create 480v.3phase to run machine tools. I have a qualified electrician ready to hook up transformer but he's not a transformer expert so I want to find out about issues in doing this. I know influx current will be momentarily high and we're prepared to deal with that. Big question I tried to get GE customer service to answer was whether this transformer, given where taps are etc., will present any huge problems. The GE instruction cited on the label pictured, only mentions the high influx current issue, but nowhere says you cant reverse-feed it. Then there's the ground issue. The only way I've read that you can create a ground for your loads is to use a corner ground, typically done by grounding the B phase. Comments?

The short answer is yes, this transformer can be fed from either side. Back in the old days, like before 2011, it was done all the time, backfeed a transformer, corner ground it and your done.

Electrons are dumb as a rock and don't care about labels or tech support opinions. Motors are dumb as a rock, they don't care about anything other than having the correct voltage fed to them. Electronics are a different matter, they are still dumb, but they require some special handling.

 

[JFletcher]

If you need a wye secondary (277/480V; i.e., a neutral), then that transformer will not work. It is also 480V - 208Y/120V, so if reverse fed, you need 208V on the primary; 240V will be too hot (high a voltage). Yes, it can be fed from either side.

 

[Jraef]

Here is a interesting read from GE on the subject:
http://apps.geindustrial.com/publibrary/checkout/Transformer2?TNR=White Papers|Transformer2|generic

What's interestingly relevant in that paper is the fact that it indirectly states that for GE, they are insisting that step-up transformers be custom built to order, which then plays to the NEC requirement* that transformers used to step-up voltage be approved for use by the manufacturer, either on the nameplate of in some other form of documentation. That paper to my reading means you cannot legally use GE transformers for step-up.

*Depending on which code cycle you are on.

 

[GoldDigger]

... That paper to my reading means you cannot legally use GE [step-down] transformers for step-up.

FIFY


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[Jraef]

FIFY


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Yeah, OK... sheesh:roll:

Commonnm,
By the way this was a duplicate thread. Please refrain from cross posting in the future. I'm merging this thread into the one you started yesterday.