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#17904 - 12/04/02 10:37 AM 75hp current draw
VOLTS Offline
Member

Registered: 06/02/01
Posts: 21
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.

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#17905 - 12/04/02 11:11 AM Re: 75hp current draw
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
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.

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#17906 - 12/04/02 02:36 PM Re: 75hp current draw
electric-ed Offline
Member

Registered: 07/08/02
Posts: 184
Loc: Canada
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

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#17907 - 12/04/02 03:23 PM Re: 75hp current draw
golf junkie Offline
Member

Registered: 04/22/01
Posts: 511
Loc: York, NE
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).]

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#17908 - 12/04/02 03:42 PM Re: 75hp current draw
Wirenuttt Offline
Member

Registered: 11/10/02
Posts: 267
Loc: Massachusetts
Just wondering, what's wrong with an amp meter?

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#17909 - 12/04/02 03:52 PM Re: 75hp current draw
go-go Offline
Member

Registered: 08/08/02
Posts: 42
Loc: Fla.
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 data...ACMotors%5FPump

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

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#17910 - 12/04/02 04:49 PM Re: 75hp current draw
Bjarney Offline
Moderator

Registered: 04/10/02
Posts: 2561
Loc: West-Southern Inner-Northeast ...
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).]

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#17911 - 12/05/02 05:23 AM Re: 75hp current draw
VOLTS Offline
Member

Registered: 06/02/01
Posts: 21
The information was helpful thank you!

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