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#17904 12/04/02 02:37 PM
Joined: Jun 2001
Posts: 21
V
VOLTS Offline OP
Member
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.

#17905 12/04/02 03:11 PM
Joined: Jul 2001
Posts: 599
J
JBD Offline
Member
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.

#17906 12/04/02 06:36 PM
Joined: Jul 2002
Posts: 175
E
Member
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

#17907 12/04/02 07:23 PM
Joined: Apr 2001
Posts: 507
G
Member
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).]

#17908 12/04/02 07:42 PM
Joined: Nov 2002
Posts: 267
W
Member
Just wondering, what's wrong with an amp meter?

#17909 12/04/02 07:52 PM
Joined: Aug 2002
Posts: 42
G
Member
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).]

#17910 12/04/02 08:49 PM
Joined: Apr 2002
Posts: 2,527
B
Moderator
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).]

#17911 12/05/02 09:23 AM
Joined: Jun 2001
Posts: 21
V
VOLTS Offline OP
Member
The information was helpful thank you!


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