Transformer Hi-Pot testing 1

[sh7035]

What is the recommended voltage test level on a transformer winding. My old rule of thumb is 2x the working voltage. Is this OK with a DC tester?

 

[controlnovice]

For testing transformers we do several tests.

Disconnect all high, low and neutral connections. Tie all high voltage connections together, all low voltage connections together with neutral. Megger, and maintain for 1 minute,

1) the high voltage winding to low voltage(with Neutral)and to ground,
2) High voltage winding to ground,
3) Low voltage winding to high voltage winding and to ground,
4) Low voltage winding to ground,
5) and High voltage winding to low voltage winding.

For oil filled transformer:
Transformer Voltage: 0 -600, DC test: 1000V, Min acceptable resistance: 100 Mohms
Transformer Voltage: 601 - 2500, DC test: 2500, Min acceptable resistance: 1000 Mohms
Transformer Voltage: 2501 - 15000, DC test: 5000. Min acceptable resistance: 5000 Mohms

I don't know if these are the recommended test voltages or where the source came from. Unfortunately, that is not documented in our test procedures.

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This is normally the space where people post something insightful.

 

[Senselessticker]

I don't have the document handy at the moment. But I believe NETA should have some recommended practice for hi-pot testing.

 

[rob46]

The link to NETA ATS 2003 is

http://www.7x24lonestar.org/files/724/Documents/17/Acceptance Testing Specs NETA 2003.pdf.