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Is it possible to have a negative Voltage Unbalance reading from a circuit monitor or a power meter?

No, it is not possible to have negative Voltage Unbalance reading from a Series 800 Power Meter or a Series 3000/4000 Circuit Monitor. All voltage unbalance readings will be an absolute value expressed as a percentage of unbalance. Voltage Unbalance is calculated using the following formula: Vunbalance = [(Vavg-Vphase) divided by Vavg].
It is possible, however, to have negative Voltage Unbalance readings if the device is a Series 600 Power Meter or a Series 2000 Circuit Monitor. These devices express Voltage Unbalance as a positive or negative percentage.

In general the absoute value of any Voltage Unbalance larger than 2.5 can cause heating in motors.



Version: Series 600 Power Meter
Series 800 Power Meter
Series 2000 Circuit Monitor
Series 3000 Circuit Monitor
Series 4000Circuit Monitor

© Schneider Electric 2005
Original article#1078

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