CLCH-SVX07C-EN 105
Start-Up
Calculate Motor Voltage Imbalance
After startup, measure the motor voltage and amperage on all phases to ensure proper operation.
The readings should fall within the range given on the motor nameplate. The maximum allowable
voltage imbalance is 2 percent.
Voltage imbalance is defined as 100 times the sum of the deviation of the three voltages from the
average, divided by twice the average voltage. For example, if the three measured voltages are 221,
230 and 227, the average voltage would be 226 volts. The percent of voltage imbalance is then
calculated.
Voltage imbalance =
where:
A = (226-221) + (230-226) + (227-226)
Voltage imbalance = 2.2% (not acceptable)
In the example, 2.2 percent imbalance is not acceptable and the power company should be notified
to correct it.
100A
2
AvgVoltage×
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