Kw rating of a motor

[Jk1996]

Hi, is the Kw rating on a motor mechanical output? I’m trying to get my head round if I can use a 7.5kw isolator for a 7.5kw motor?

 

[che12345]

@ Mr waross (Electrical)9 Feb 23 02:41
"...To expand on Mr Che Kuan Yau's post:
30.8 Amps at 208 Volts = 11.088 electrical kW. "
No.
Per NEC Table 430-150 , the typical 10 hp full-load current 30.8 A at 208 V. Expanding " 30.8 Amps at 208 Volts = 11.088 electrical kW " is NOT called for by the NEC. It is incorrect and is in conflict with the intention of the Tabulated value in the NEC, which is the Law in the US.
Che Kuan Yau (Singapore)

 

[LionelHutz]

When it comes to motor control stuff, the NEC is not the law. I work with motor controls every day and generally don't give a shit what the NEC or the CEC says. Hardly need to look at either.

 

[waross]

I am confused?
What has "Per NEC Table 430-150 ,......" to do with an explanation of the difference between electrical kW and mechanical kW as applied to electric motors?
Using mechanical kW to select a standby generator capacity may result in an unhappy customer.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[che12345]

@ Mr waross (Electrical)9 Feb 23 16:52
"...I am confused? What has "Per NEC Table 430-150 ,......" to do with an explanation of the difference between electrical kW and mechanical kW as applied to electric motors?..."
Refer to the question raised by Mr Jk1996 (Electrical)(OP)26 Jan 23 13:51
Hi, #1. is the Kw rating on a motor mechanical output? #2. I’m trying to get my head round if I can use a 7.5kw isolator for a 7.5kw motor?, .... comprising of two different questions.
Question #1. had been fully answered. Now we are on question #2. , to avoid any confusion.
Che Kuan Yau (Singapore)

 

[Maximillianrichards]

The kW rating on a motor is its electrical power rating, which is a measure of the amount of electrical energy it consumes. The mechanical output of a motor is typically lower than its electrical power input due to losses from the efficiency of the motor.

You can use a 7.5 kW isolator for a 7.5 kW motor, but it is important to make sure that the isolator has the correct current rating for the motor and that it is suitable for the voltage and frequency of the power supply. Additionally, you should check that the isolator complies with relevant electrical safety standards and regulations.

 

[LionelHutz]

The kW rating on a motor is its electrical power rating, which is a measure of the amount of electrical energy it consumes.

No, wrong.