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#74705 - 02/02/07 07:34 AM operating cost?
Rob Offline

Registered: 12/22/03
Posts: 15
Loc: New York
How do you determine operating cost of a 3 phase motor. 460 volt 15 amp.
My utility rate is .08 cents per kwh.
Is there a common formula?

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#74706 - 02/02/07 07:58 AM Re: operating cost?
renosteinke Offline
Cat Servant

Registered: 01/22/05
Posts: 5305
Loc: Blue Collar Country
Measure the actual amps drawn on each leg. Average. Multiply by 1.73. That's your amp load.

From there, it's the usual amps x volts x time x rate = electrical cost.

This will give you figures good enough to work with. Actual results will vary a bit, due to changes in load, power factor, harmonics, etc ... but the number you get will be close enough for budgeting.

#74707 - 02/02/07 02:20 PM Re: operating cost?
JBD Offline

Registered: 07/12/01
Posts: 599
Loc: WI, USA
One quick and dirty method is to estimate 1KVA of input power for each HP of output.

For a fully loaded motor you can use 1KW per HP. For lightly loaded motors use 1.1KW per HP instead.


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