3.4 Transformer Connections

In order to monitor generator output voltages greater than 600 Volts, external potential transformers must be used.

Star 3-Wire Delta 4-Wire Delta 2-Wire 1-Phase

3-Wire 1-Phase

Gen Freq (0066h) OK OK OK OK OK VL-L AVG (0064h) OK OK OK OK OK VA-B (006Ch) OK OK OK OK OK VB-C (006Dh) OK OK OK Invalid Invalid VC-A (006Eh) OK OK OK Invalid Invalid VL-N AVG (0094h) OK Invalid OK Invalid OK VA (0072h) OK Invalid OK Invalid OK VB (0073h) OK Invalid OK Invalid OK VC (0074h) OK Invalid OK Invalid Invalid IAVG (0065h) OK OK OK OK OK IA (006Fh) OK OK OK OK OK IB (0070h) OK OK OK OK OK IC (0071h) OK OK OK Invalid Invalid Note: The EMCP 3 must be programmed for the correct winding ratios when connecting external potential transformers. See “Setpoint Programming” for more information on how to program the winding ratios. Note: The wye configuration of external potential transformers is preferred for 4-wire wye generators because of the greater accuracy when loads are unbalanced. With the open delta configuration, some power parameters can not be determined. These parameters are real power phase A, B, C and power factor phase A, B, C. For maximum accuracy, the open delta configuration of external potential transformers should be used only for 3-wire delta generators.