600V Generator for 480V System

[bfdeleen]

If I have an existing 600 volt, 3 phase, 60 Hz generator, approx 1500 kva, can I use it on a 480 volt system. The field current must be lower and the rating reduced to 1200 kva. Is this possible?

 

[mpparent]

I don't think that would be recommended.

 

[gordonl]

I'm not so sure there is anything wrong with this idea, certainly overexciting the field would be a concern but as long as the stator current limit is maintained as bfdeleen is doing, it seems OK to me.

 

[peterb]

There should be no problem, providing the AVR is adjusted appropriately. The easiest way to ensure this could be to change the sensing voltage transformers, if they are used, from 600:120V ratio to 480:120V.
The generator can be loaded up to its capability curve, but this must be re-drawn for the lower terminal voltage. Why not check the manufacturer for specific recommendations?

 

[coolfish]

It might work but probably not recommened. Why not use a step down transformer instead, either three winding or auto-transformer? Of course, you will have to wire a 1.5 MVA transformer which could be substantial in size.

 

[dydt]

Economically speaking, I will be looking at using an auto-transformer. The stepdown voltage is not much so the size of the winding will only be heavy on 480 to 600V range. Should be much cheaper than an induction. Your genset is just a back-up right? so the transformer power consumption should be negligible.

dydt

 

[bfdeleen]

In this case, the owner has the generator at one site which is downsized and would like to see if it can be used on another of their sites that is being expanded. Minimum cost is the first choice so I will try to reuse it at the lower voltage.