DC motor FLA

[StanleySmith]

hey guys, I'm using a 120/220VAC drive to power a 1/3 HP DC motor. I want to calculate the FLA.
What's the formula??? Can I use this relatioship 1HP =746W =746x1Vx1Amp ?
Thank you,

 

[Skogsgurra]

"a 120/220VAC drive to power a 1/3 HP DC motor"

How do you mean? Connecting a DC motor to an AC drive? I do not understand.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[itsmoked]

Roughly yes! You can use that formula. It would, of course, exclude all the losses (~20%) and it won't describe the starting current.

And Skog's question remains...

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[StanleySmith]

Sorry, It's a AC-DC converter. AC line voltage is 115/230, and it produces 0-90 VDC/0-180 VDC armature voltage...

 

[Skogsgurra]

It depends on what the rated voltage is. If it is 90 V and we assume 80 % efficiency, then your FLA will be something like 250[W]/90[V]/.80 = 3.5 A. If it is 180 V, you will get half of that current.

Is there an excitation winding as well? If so, is it supplied by a separate rectifier - or do you supply it from the main rectifier. In the latter case, you need to add the field winding current to the total.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[aolalde]

For the DC motor circuit:
I = Pe/V
were:
Pe = electric power supplied in watts = Pot/EFF
V = motor input voltage
Pot = Mechanical Power output in watts
EFF = Motor efficiency