Transformer PM Best Practices

[electriken]

Can someone offer a short summary of Transformer PM Best Practices for visual, mechanical, and electrical testing/inspection and the recommended intervals. The particular one in question is a customer owned, pad mount, 12.5kV x 480V serving critical loads.

 

[oldfieldguy]

Well, pad mounted transformers are generally treated differently than regular power transformers. Their very design is made for a "set it and forget it" philosophy.

However, since it is critical, I would recommend the tests outlined in NETA Maintenance Test Specification: Oil sampling annually for dissolved gases and physical properties, and electrical tests every two years, three if it's in a nice, clean location.

old field guy

 

[NCTHAI]

Electrical Test - Annualy
- IR
- Wdg Resistance
- Low voltage excitation current
- Earth Resistance measurments

Protection Tests - Annual
- Bucchholz
- PRV
- Protection relays if installed

Inspection - Annual
- For oil leak
- Corrosion
- Earthing - protective
- Connection Tightness
- Bushing Inspection

Other
- DGA - Annual / as required
- Structural Integrity

Hope this helps.

NC