Fluke 434 - Manual (Page 35)

Volts/Amps/Hertz
Tips and Hints
8
8-3
Tips and Hints
Voltage and frequency should be close to the nominal values of for example 120 V, 230
V, 480 V, 60 Hz, or 50 Hz.
The voltages and currents in the table can e.g. be used to check if power applied to a 3-
phase induction motor is in balance. Voltage unbalance causes high unbalanced currents
in stator windings resulting in overheating and reduced motor life. Each of the phase
voltages should not differ more than 1 % from the average of the three. Current
unbalance should not exceed 10 %. In case of too high unbalance, use other measuring
modes to further analyze the power system.
A Crest Factor close to 2.0 indicates high distortion. CF = 2.0 can e.g. be found if you
measure the current drawn by rectifiers that only conduct at the sine wave top.