Current and Voltage

Instantaneous Current

MicroLogic P trip units offer two, non-exclusive measurement possibilities.

On the bar graph displayed on the default screen
- The instantaneous current of the most heavily loaded phase is automatically displayed in amperes for phases 1, 2, 3 and the neutral (depending on the neutral protection settings). The bar graph indicates the percent load of the three phases.
In the I inst. section of the instantaneous currents
- Display in amperes of the instantaneous currents I (rms) on phases I1, I2 and I3 and the neutral current IN, the ground-fault current Ig (MicroLogic 6.0 P), the earth-leakage current IΔn (MicroLogic 7.0 P)
- The maximum instantaneous currents are displayed and stored in memory.
- The stored maximums can be reset at any time.

NOTE: For the measurement ranges and accuracies, see Measurement Ranges and Accuracy .

Demand Current

Display of the demand current on phases I1, I2, I3 and the neutral IN (depending on the type of distribution system)
Selection of the demand calculation method
Display of the interval over which the value is calculated
The maximum demand values are displayed and stored in memory
The stored maximums can be reset at any time.

NOTE: The calculation method, the type of calculation window (fixed or sliding) and its duration may be set in the Metering setup menu under History, maintenance and setup.

Phase-to-Neutral and Phase-to-Phase Voltages

The MicroLogic P trip unit offers different voltage measurements:

Phase-to-phase voltages (rms) between phases U12, U23 and U31, displayed in volts
Phase-to-neutral voltages (rms) between the phases and the neutral V1N, V2N and V3N, displayed in volts.

NOTE: To display the phase-to-neutral voltages, select the 3Φ 4F4CT option in System type in the Metering setup menu under History, maintenance and setup.

For more information about voltage measurement inputs, refer to Selection of the Voltage-Measurement Inputs.

The supply circuit of the voltage-measurement input is reserved exclusively for the trip unit and must never be used to supply other circuits.

Average Voltage

Average U avg of the instantaneous voltages between phases U12, U23 and U31.

Phase Rotation

Display of the phase sequence.

Voltage Unbalance

Display of the unbalance U unbal between the three phase-to-phase voltages, displayed as a percentage.