AC Motor Current draw
AC Motor Current draw
(OP)
Please help me understand this formulation.
say the motor is a three phase ac induction motor (asynchronous).
with the following specifications
575 V, 2 HP, 1740 RPM, Efficiency nominal/full load = 0.86
PF (full load Power Factor) = 0.78 PF (50% Load Power Factor) = 0.57
The formula to calculate the current is
I = 746*HP / (1.73*V*Eff*PF)
At full load the current drawn is ~ 2.2 amps
At half load the current drawn is ~ 3 amps.
it does not make sense? I think I am missing something here, does this mean at no load it will draw high current?
please point out where I am going wrong. Thanks in advance
say the motor is a three phase ac induction motor (asynchronous).
with the following specifications
575 V, 2 HP, 1740 RPM, Efficiency nominal/full load = 0.86
PF (full load Power Factor) = 0.78 PF (50% Load Power Factor) = 0.57
The formula to calculate the current is
I = 746*HP / (1.73*V*Eff*PF)
At full load the current drawn is ~ 2.2 amps
At half load the current drawn is ~ 3 amps.
it does not make sense? I think I am missing something here, does this mean at no load it will draw high current?
please point out where I am going wrong. Thanks in advance





RE: AC Motor Current draw
So, at half load, the current drawn should be ~1.5A
Try to be perfect. You'll never make it, but you will be very, very good.
RE: AC Motor Current draw
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(2B)+(2B)' ?
RE: AC Motor Current draw
RE: AC Motor Current draw
Bill
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"Why not the best?"
Jimmy Carter
RE: AC Motor Current draw
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(2B)+(2B)' ?
RE: AC Motor Current draw
I presented this more as an approximation and explanation than an in-depth rigorous solution that may leave some readers lost in the numbers.
Yours
Bill
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: AC Motor Current draw
I_100 =746*HP /(1.73*V*Eff*PF)= (746*2/(1.73*575*0.86*0.78) )=2.2
I_50 =746*HP /(1.73*V*Eff*PF)=(746*2/(1.73*575*0.86*0.57) ) = 3.0
What's wrong with this calculation has nothing to do with the value of pf plugged in and everything to do with the value of HP plugged in. jmontero nailed it straightaway. The only reason I chimed in is that our posts were so close in time that I never saw his.
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(2B)+(2B)' ?
RE: AC Motor Current draw
=====================================
(2B)+(2B)' ?
RE: AC Motor Current draw
=====================================
(2B)+(2B)' ?