for a 400kV or 380kV 300MVA Power Transformer what should be the voltage level selected for carrying out the Polarization Index. as these transformers have large capacitances in comparision to the solid insulation HV motors?

Accoriding to NETA Standard MTS-001, Table 10.5, test voltage for liquid filled transformers rated above 5kv should be:
5kvdc, minimum.

They don't say anything about a maximum...I assume if your instrument goes to 10kv or 15kv those would be ok provided the transformer is liquid filled. As I remember, there may be some important precautions against testing liquid-filled transformer while drained.

[QUOTE]Accoriding to NETA Standard MTS-001,QUOTE]

Is it NEMA, and if not may i have table 10.5