When you see a motor in a factory for a pump or something etc. and it is rated at 150HP is this input or output power? If the 150HP pump is rated for use @480V and has an FLA of 180A it would be 150KVA(approx) if the PF is approx 0.85 then does that mean the motor requires 150KVA with an output of approx,. 127.5KW or is the the input of the motor required to be 150/0.88 to equal the KVA required to run the motor?
Motors?
- Thread starter Mike01
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Motors are rated in output power. So, to determine the true input power required you need to know the efficiency as well as the PF of the motor.
As you have discovered, a "rule of thumb" method is size the input KVA to the motor equal to its output power, 1HP output = 1kVA input.
To determine input kW you need to know efficiency.
To determine input kVA you need both efficiency and PF.
weressl
Esteemed Member
A motor rating always refers to its mechanical shaft output power. The motor efficiency is the conversion of electrical energy into mechanical energy and it is always less than 1.00. Power factor is also a factor between the apparent and 'real' electrical power that electrical equipment uses. In otehr than purely resistive loads it is also always less than 1.00.
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