Tan delta testing of transformer Winding: Test Procedure with Standard Test Results I Transformer Diagnostic Testing I Transformer Testing
Purpose of the Test:
- Insulation assesment of the Transformer for detecting Moisture, Carbonization/Contamination and Mechanical Failure.
Test Procedure:
- Completely Isolate the Transformer. Neutral Earthing (If exists), is to be removed.
- Short all Bushings (R, Y & B Phase) of same voltage level together, with the help of bare braided copper jumper.
Two Winding Transformer:
| Winding | Mode | Tan Delta (%) | Capacitance (pF) |
|---|---|---|---|
| HV-LV (CHL) | UST-R | ||
| HV-GND (CH) | GAR-R | ||
| HV-LV + GND (CH+CHL) | GND-RB | ||
| LV-HV (CHL) | USt-R | ||
| LV-GND | GAR-R | ||
| LV-HV + GND (CL+CLH) | GND-RB |
Standard Test Results:
Typical values are normally in the order of %. A Measurement higher than 1% is questionable.