225kVA - 2000kVA @ 480VAC Tranformer Test

[Tony Boccella]

Question#1: When supplying a portable generator for the testing of various sized transformers (225, 500, 750, 1000, 1500, and 2000kVA) do I need a generator to match each specific transformer or can I use one size generator as the load should be felt at the transformer, right?

Question#2: Is there any deration that should be observed when dealing with transformers and/or standby generator?


Thank you all in advance!

 

[petersonra]

Question#1: When supplying a portable generator for the testing of various sized transformers (225, 500, 750, 1000, 1500, and 2000kVA) do I need a generator to match each specific transformer or can I use one size generator as the load should be felt at the transformer, right?

Question#2: Is there any deration that should be observed when dealing with transformers and/or standby generator?


Thank you all in advance!

I don't understand what you mean by the "load being felt" comment.

In general, the transformer is not going to care any. All the transformer cares about is getting the right voltage at the right frequency. However, some generators are not real thrilled with being very lightly loaded.

What is it you want to derate? The transformer? The generator? The wiring between them?

I suspect that you have one or more specific question(s) that you want answered but are unwilling to just ask them.

It is very hard to answer questions that are as vague as the ones you are posing.

 

[Tony Boccella]

Transformer Test

Transformer Test

Ok so in a nut shell... what I would like to know is, when you hook a temporary generator to a transformer (sizes already stated) and a load is also connected, do I need to size the generator to each specific transformer or can I use a 750kVA generator and test all the transformers from 225-750kVA??? I apologize for coming across vague/confusing first round. :slaphead:

 

[zog]

Question#1: When supplying a portable generator for the testing of various sized transformers (225, 500, 750, 1000, 1500, and 2000kVA) do I need a generator to match each specific transformer or can I use one size generator as the load should be felt at the transformer, right?

Question#2: Is there any deration that should be observed when dealing with transformers and/or standby generator?


Thank you all in advance!

What type of testing are you doing?

 

[petersonra]

Ok so in a nut shell... what I would like to know is, when you hook a temporary generator to a transformer (sizes already stated) and a load is also connected, do I need to size the generator to each specific transformer or can I use a 750kVA generator and test all the transformers from 225-750kVA??? I apologize for coming across vague/confusing first round. :slaphead:

I will say this again. As long as it is getting the correct voltage and frequency, the transformer just does not care.

I noticed you changed from 225-2000kVA in the first post to 225-750kVA in this one.

The generator might have some issues depending on what the load profile looks like.

I have worked on a bunch of test stands for applying loads to various things, and they often do some really odd ball things like running unbalanced loads (unbalanced between phases) or really low power factor loads.

I would find out what the load profile of the tests are going to be and pass them on to the generator manufacturer and see what they think.

 

[GoldDigger]

Sounds like an unloaded 2000kVA transformer would be a large low power factor load all right. And the connection surge could be hard on the generator.

 

[zog]

Ok so in a nut shell... what I would like to know is, when you hook a temporary generator to a transformer (sizes already stated) and a load is also connected, do I need to size the generator to each specific transformer or can I use a 750kVA generator and test all the transformers from 225-750kVA??? I apologize for coming across vague/confusing first round. :slaphead:

Did someone call you to rent a generator for transformer testing? I suspect you misunderstood what they are asking for.

 

[Besoeker]

Sounds like an unloaded 2000kVA transformer would be a large low power factor load all right.
Low power factor but not a large load. I've just recently had a quotation in for a 950kVA transformer.

This from the proposed manufacturer's spec:

Total rating: 950kVA
Vector group: Ddoyn11
No load loss: 2550 watts

And the connection surge could be hard on the generator.

I think the OP is wanting to test a range of transformers.
A generator large enough to power the largest transformer should do bearing in mind that the generator power factor may be 0.8.
Maybe inrush could be a problem but if it's for test purposes only the generator voltage could be raised after the transformer is connected. I don't know if all AVRs have that facility. The ones we make (not mainstream business for us) can ramp the voltage up.

But I don't think it's all that common for transformer manufacturers to do full rating tests. Those that I've witnessed have had the load losses measured with the output shorted and just enough input voltage to produce full load current. That and the no-load losses are combined.

I can't recall any full power tests that I've witnessed - the cost of the wasted power not to mention the practical difficulty of dissipating all the heat......
Back to back tests are possible with two with the supply providing just the losses for both transformers.