Electronic Modular Control Panel II+ (EMCP II+) for EUI Engines Caterpillar

Illustration 1	g00584152
Wye Configuration Of External Potential Transformers (PT) On 4-Wire Wye Generator This configuration allows the accurate measurement of all power parameters by the GSC+ including when the loads are unbalanced and neutral current is present. All power parameters are shown on the display of the GSC+.

Illustration 2	g00584153
Open Delta Configuration Of External Potential Transformers (PT) On The 3-Wire Delta Generator This configuration allows the accurate measurement of power parameters by the GSC+ including when the loads are unbalanced and circulating current is present. The real power phasecan not be determined. The power factor phase can not be determined. The phases are not shown on the GSC+ display.

Illustration 3	g00584154
Open Delta Configuration Of External Potential Transformers (PT) On The 4-Wire Wye Generator This configuration results in less accurate measurement of all power parameters by the GSC+ when the loads are unbalanced and neutral current is present. Real power phase and power factor phase are not shown on the GSC+ display.

Note: The wye configuration of external potential transformers (PT) 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 the real power phase (A, B, C) and power factor phase (A, B, C). For maximum accuracy, use the open delta configuration of the external potential transformers. This should be used only for 3-wire delta generators.

On 4-wire wye generators, three separate potential transformers (PT) are required for accurate power metering unless the loads are continually balanced. Even if the loads are balanced, some power parameters can not be determined. The following parameters are not shown on the GSC+ display: the real power phase and power factor phase. The ATB+ contains three potential transformers in order to accommodate 4-wire wye generators. The full capabilities of the ATB+ are not utilized when an open delta PT configuration is used for 4-wire wye generators.

On 3-wire delta generators, two potential transformers allow maximum accuracy for all load conditions. The real power phase can not be determined. The power factor phase can not be determined. The previous two phases are not shown on the GSC+ display.

When you are connecting an external potential transformers to a ATB+, the GSC+ must be programmed.

Procedure For Programming When Potential Transformers Are Used

1. Program setpoint P032 in order to match the configuration of the external potential transformer. Setpoint P032 must always match the configuration of the external potential transformer. This should be done regardless of the configuration of the generator. This is necessary because the ATB+ is connected only to the external potential transformers. The ATB+ cannot sense the generator's connections.
   • For external potential transformers that are connected in a wye configuration, program setpoint P032 to 0 (wye). Setpoint P032 is also programmed to 0 when no potential transformers are present on wye configurations.

   • For external potential transformers that are connected in a delta configuration, program setpoint P032 to 1 (delta). Setpoint P032 is also programmed to 1 when no potential transformers are present on delta configuration.

   Note: When setpoint P032 is programmed to 1 (delta), the real power phase and the power factor phase can not be determined. The real power phase and the power factor phase are not shown on the GSC+ display.

2. Program the setpoint P020 to match the external potential transformer's turn ratio. See Testing And Adjusting, "AC Voltage Range - Adjust". Setpoint P020 should match the external potential transformer's turn ratio. The ratio should match the setpoint P032 regardless of the generator's configuration.