Transformer test

[alce]

We have a three distribuiton transformer (1MVA 12.47kV/480V), and we would like to run different test to calculate the following
capacitances:
- Phase to Phase
- Primary to secondary
- Phase to ground.
I was wondering if anybody knows of any technique/procedure or circuit configuration that allows to measure such capacitances.

Alce

 

[buzzp]

I do not know of a simple way that will provide meaningful results as far as measuring the capacitance. You have probably heard of Doble Engineering. They make testers for this purpose

http://www.doble.com.

I know there is another company but I can not remember their name.

 

[mvcjr]

I don't think it would be possible to test for the phase-to-phase capacitance (in 3-phase transformers) since each phases are interconnected. In the same manner, you can not test for phase-to-phase insulation resistance of three-phase transformers unless you remove the internal interconnections.

AVO/Megger also manufactures test equipment for testing capacitance or power factor/dissipation factor.

God bless!

 

[jbartos]

Suggestion: Visit

http://www.motordoc.org/downloads/Testing.PDF

etc. for more info

 

[Jerry123]

This may help. If you are looking for a test set to give you a capacitance. You may what to use a Biddle dissipation factor test set. I only suggest this because it is what I'm familiar with. I do believe that the doble uses that same concept though. The normal tests run will give a capacitance from primary to ground, primary to secondary, and primary to secondary and ground, along with the Power Factor. This is the same for testing the secondary side.

As for phase to phase. I'm not sure if it would work, but if you can isolate the three windings you maybe able to do it. The test connection would be different.