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
Legacy KB System (APS) Data: RESL182108 V1.0, Originally authored by DaMi on 02/13/2007, Last Edited by DaMi on 02/13/2007
Related ranges: ION Other