Treatment of Resistance for single phase transformers
Treatment of Resistance for single phase transformers
(OP)
Hi...
Given that one uses the series (winding) resistance values from the transformer test reports to estimate* the resistive part of transformer impedance...
...And for a 3-phase transformer, one uses the sum of the resistance values for the 3 phases... what does one do if the given transformer is actually made up of 3 single-phase transformers?
- john
* (I know this isn't complete, but assume that's all one has available.)
Given that one uses the series (winding) resistance values from the transformer test reports to estimate* the resistive part of transformer impedance...
...And for a 3-phase transformer, one uses the sum of the resistance values for the 3 phases... what does one do if the given transformer is actually made up of 3 single-phase transformers?
- john
* (I know this isn't complete, but assume that's all one has available.)






RE: Treatment of Resistance for single phase transformers
RE: Treatment of Resistance for single phase transformers
To get one value for three single-phase transformers used together, would I add up the load loss values for each of the three phases and divide by the sum of the MVA values, to get an average resistance value?
- john
RE: Treatment of Resistance for single phase transformers
Correct. Losses would have to be expressed in MVA. You would get the per unit resistance at the transformer rating base (same base as the impedance).
RE: Treatment of Resistance for single phase transformers
If the transformer is three-phase, the short circuit transformer test is a three-phase transformer test. This way the transformer connections can stay intact. If the transformer is a single phase, than the results will be obtained for a single phase transformer. If the three phase transformer consists of three single phase transformers, than there is a choice. The three phase connected single phase transformers will be more representative for the measurement, test and calculation results.