GE EPM 9650/9800 manual Chapter Modbus Register Map Notes

Chapter 4

Modbus Register Map Notes

4.1: Modbus Register Map Notes

The information in this chapter refers to the Register Map’s “Notes” column.

1)Time information can be supplied from one of two different sources, an internal Real Time Clock or an external GPS Clock. The internal Real Time Clock is a chip containing its own battery, which is used to maintain the passage of time when the EPM unit is without operational power. It is similar to those used in PCs and it reports time accurate to the second. The external GPS clock is supported through an IRIG-B connection, allowing synchronization and accuracy to the hundredth of a second (10 milliseconds).

2)These registers, when read, always report the time as reported by the EPM unit, either from the internal Real Time Clock or the external GPS Clock. Values written here for the purpose of updating the internal Real Time Clock are not read back.

3)These values are calculated by the EPM Comm Processor, as part of the Waveform Capture function. These values are only calculated if the EPM device has Waveform Logging Capability.

4)Phase Voltages are in secondary Volts. To convert this value into primary Volts, multiply by the Phase Voltage PT Ratio, composed of the Phase Voltage PT Ratio Numerator and Denominator (Registers 45916 - 45917 and 45918 - 45919).

5)Auxiliary Voltage is in secondary Volts. To convert this value into primary Volts, multiply by the Auxiliary Voltage PT Ratio, composed of the Auxiliary Voltage PT Ratio Numerator and Denominator (Registers 45920 - 45921 and 45922 - 45923).

6)Phase and Calculated Neutral Currents are in secondary Amps. To convert this value into primary Amps, multiply by the Phase Current CT Ratio, composed of the Phase Current CT Ratio Numerator and Denominator (Registers 45908 - 45909 and 45910 - 45911).

7)Measured Neutral Current is in secondary Amps. To convert this value into primary Amps, multiply by the Auxiliary Current CT Ratio, composed of the Auxiliary Current CT Ratio Numerator and Denominator (Registers 45912 - 45913 and 45914 - 45915).

8)Measured Neutral is the RMS produced by samples from a CT around the Neutral Line and connected to the Neutral current terminals of the EPM9650. Calculated Neutral is the RMS produced by adding the three Phase Current samples together and treating the result as a sample of the neutral line.

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