Originally posted by sparky:
Redsy,
is there a recommended overall % , or would that be motor make , brand...???
Sparky,
The book states that "induction motors will operate successfully under running conditions at rated load with a voltage variation of 10% at the motor terminals. A frequency variation of 5% is permissible. A combined variation of voltage and frequency of 10% is acceptable provided the frequency doesn't vary by more than 5%(i.e. 7% voltage variation with 3% frequency variation).
Also: the effects of overvoltage are shown:
Starting amps--decrease
Full load amps--increase
Efficiency--decrease
P.F.--decrease
Torque--decrease.
Notice that undervoltage AND overvoltage are shown to increase Full-load amps.
It says that low voltage will cause higher than normal current to the point of over heating.
It also says that a SMALL increase in voltage could reduce current draw, but increases in excess of 10% cause saturation of the iron and a significant increase in current draw with accompanying overheating.
