EMCP3 Caterpillar

Winding Connections

The wiring connections that are used between the generator and the EMCP 3 depend upon the winding configurations of the generator. Refer to the following connection diagrams.

Illustration 1	g01512173
Three phase four wire (series or parallel) wye (star)

Illustration 2	g01512193
Three-phase four-wire delta

Illustration 3	g01512213
Three-phase three-wire delta

Illustration 4	g01512215
Single phase three-wire (double delta)

Illustration 5	g01512236
Single phase two-wire (double delta)

Transformer Connections

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

Note: The EMCP 3 must be programmed when connecting external potential transformers.

Reference: Systems Operation, RENR7902, "Setpoint Programming" and Testing and Adjusting, "Electronic Control Module (Generator Set) - Configure".

Note: The wye configuration of external potential transformers is preferred for 4-wire wye generators. The preference is due to the greater accuracy when loads are unbalanced. With the open delta configuration, some power parameters cannot be determined. The 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.

Illustration 6	g01228369
Wye configuration with external potential transformers for the 4-wire wye generator

The wye configuration allows the accurate measurement of all power parameters by the EMCP 3. Accurate measurement is possible even when the loads are unbalanced and neutral current is present. All power parameters are shown on the display of the EMCP 3. The EMCP 3 configuration parameter" Generator Connection Configuration" must be set to wye or star.

Illustration 7	g01228370
Open delta configuration of external potential transformers for the 3-wire delta generator

Note: The open delta configuration for 3-wire delta generators allows the accurate measurement of power parameters by the EMCP 3. Accurate measurement is possible even when the loads are unbalanced and circulating current is present. The real power phase A, B, and C cannot be determined. The power factor phase A, B, and C cannot be determined. The phases are not shown on the EMCP 3 display. The EMCP 3 configuration parameter "Generator Connection Configuration" must be set to "delta 3-wire".

Illustration 8	g01228371
Open delta configuration of external potential transformers on the 4-wire wye generator

Note: The open delta configuration for 4-wire wye generators results in less accurate measurement of all power parameters by the "EMCP 3". The open delta configuration results in less accurate measurement when the loads are unbalanced and neutral current is present. Real power phase A, B, C and power factor phase A, B, C cannot be determined and are not shown on the "EMCP 3" display. The EMCP 3 configuration parameter "Generator Connection Configuration" must be set to "delta 3-wire".

On 4-wire wye generators, three separate potential transformers are required for accurate power metering unless the loads are completely and continually balanced. Even if the loads are balanced, some power parameters cannot be determined. Real power phase A, B, C, and power factor phase A, B, C are not shown on the EMCP 3 display.

On 3-wire delta generators, two potential transformers allow maximum accuracy for all load conditions. Real power phase A, B, C and power factor phase A, B, C cannot be determined and are not shown on the EMCP 3 display.