What would a 75hp 480 vac 3 phase motor draw if it were not connected to anything? Just wired up sitting on a table runnng? Is there a table or a formula anyware all the tables I find are for full load amps.

There are no formulas, too many variables. One rule of thumb I have seen is 75% FLA, but my experience says this is on the high side.

70 to 75% of rated current is about right. The reason - The magnetizing component of the current is the same whether the motor is at full load or no load.

Ed

My experience tells me it's closer to 50% than 75%. 50 may be on the low side though.

FWIW
GJ

[This message has been edited by golf junkie (edited 12-04-2002).]

Just wondering, what's wrong with an amp meter?

Volts,
Baldor lists a 75hp model JPM2551T as FLA @ 208v-176a FLA @ 460v-88a and the no- load current at 30.2a http://www.baldor.com/products/perf...s&family=Pump%7Cvw%5FACMotors%5FPump

[This message has been edited by go-go (edited 12-04-2002).]

Good, informative link, go-go.

FLC/NLC = 87.7/30.2 amperes = 35% [surprisingly low]

Power Factor (25% load) = 53% [rotten!]

PF at zero load is not listed, but likely less than 50%. [Way rotten!]




[This message has been edited by Bjarney (edited 12-04-2002).]

The information was helpful thank you!