PFC for Transformers

PFC for Transformers

For an exact calculation of the right capacitor value, following formula can be used: 

Qc  = needed capacitor (kvar) 

Io% = magnetising current of the transformer (AS%)

AN  = apparent rated power of the transformer in kVA

There are regional differences in the guidelines of power suppliers con- cerning the admissible size of ca- pacitors directly connected with a transformer. Therefore a consultation with the respective power supplier is recommended before installation of a compensation bank. Modern transformers have laminations which only need low capacity to reverse the magnetism. In case the capacitor output is too high, stress increase may occur during idling.

Standard values for transformer power factor correction (PFC)