Dry Tranformer Turns Ratio

[shamimkhan]

How much deviation is allowed from the calculated value ( three phase dry transformer Rated voltage 11000 / 415 volts, Rated Power 2000KVA)? Kindly also mention the reference of Standard.

[SecondGen]

The standard deviation as defined by ANSI/IEEE C57.12.00-2006, Section 9.1 states that results should be within 0.5% of nameplate markings, with rated voltage applied to one winding. The TTR with accuracy of 0.1% is accepted as a referee.

- Power Equipment Maintenance and Testing, Paul Gill


ANSI/NETA standards also state that TTR results should be within 0.5%

[jflan13]

How much deviation is allowed from the calculated value ( three phase dry transformer Rated voltage 11000 / 415 volts, Rated Power 2000KVA)? Kindly also mention the reference of Standard.

In the NETA-MTS and ATS under electrical test results it says, "Turns-ratio test results should not deviate more than one-half percent from either the adjacent coils or the calculated ratio." Page 32 for both books.