EMCP4.1/EMCP4.2 Caterpillar

Winding Connections

The wiring connections that are used between the generator and the EMCP 4 depend upon the winding configurations of the generator. Refer to the following connection diagrams.

Illustration 1	g02286733
Three-phase, four-wire, series, or parallel Wye (star) configuration

Illustration 2	g02286773
Three-phase, four-wire, delta configuration

Illustration 3	g02286775
Three-phase, three-wire, delta configuration

Illustration 4	g02286776
Single-phase, three-wire, double delta configuration

Illustration 5	g02286854
Single-phase, two-wire, double delta configuration

Illustration 6	g03515940
Single-phase, three-wire, L2-N-L3, zig-zag configuration

Illustration 7	g03515942
Single-phase, two-wire, L2-L3, zig-zag configuration

Transformer Connections

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

Note: The EMCP 4 must be programmed when connecting external PTs.

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

Note: The wye configuration of external PTs is preferred for 4-wire wye generators because of the greater accuracy when loads are unbalanced. With the open delta configuration, some power parameters cannot 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 PTs should be used only for 3-wire delta generators.

Illustration 8	g02286873
Four-wire Wye (Star) configuration

Illustration 8 is a typical example of a Wye configuration of an external potential transformer for the four wire Wye generator.

This configuration allows the accurate measurement of all power parameters by the EMCP 4 including when the loads are unbalanced and neutral current is present. All power parameters are shown on the display of the EMCP 4. The EMCP 4 configuration parameter " Generator Connection Configuration" should be set to WYE (or STAR).

Illustration 9	g02286876
Three-phase, three-wire, delta configuration

Open delta configuration of external potential transformers on the 3-wire delta generator

This configuration allows the accurate measurement of power parameters by the EMCP 4 including 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 4 display. The EMCP 4 configuration parameter "Generator Connection Configuration" should be set to DELTA (3 WIRE).

Illustration 10	g02286877
Three-phase, four-wire, delta configuration

The three phase four-wire is also referred to as the open delta configuration for external potential transformers on the 4-wire wye generator.

The three phase four wire configuration results in less accurate measurement of all power parameters by the EMCP 4. Less accurate measurement occurs 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 4 display. The EMCP 4 configuration parameter "Generator Connection Configuration" should be set to DELTA (3 WIRE).

On 4-wire wye generators, three separate PTs 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 4 display.

On 3-wire delta generators, two PTs 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 4 display.