Nema Design A - D

[magneticted]

Are these torque values as defined in NEMA relate to all motors. What I'm thinking is their a Kw size limit, and also is it just relate to Low Voltage Motors. And would not be appropriate to MV/HV motors irrespective of power.

 

[electricpete]

They related to small and integral horsepower motors. The cutoff is somewhere in the neighborhood 250 - 500 rpm, depending on speed.

NEMA does not apply these curves to larger motors.

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[aolalde]

As electricpete mencioned these designs per NEMA MG1 standard apply only to small and medium machines and the scope is given in par 12.0

The induction motors up to and including:
500 HP - 3600 rpm
500 HP - 1800 rpm
350 HP - 1200 rpm
250 HP - 900 rpm
200 HP - 720 rpm
150 HP - 600 rpm
125 HP - 514 rpm