NEMA Class 1 Division 2 Group D Motors

[magneticted]

With LV and MV motors is it allowed to apply a service factor of 1.15 and still keep within the allowed stator / rotor temperature limits class B

If we allowed a service factor, then the motor could be deemed to be overloaded and exceeding the T temperature classificaTION

Would this be a correct assumption

Regards

 

[weh3]

For service factor, check the motor nameplate.

Also, don't confuse the motor's design limits with the surface temperature limitation from NEC. If it comes with a surface temperature label, then it will also have a thermal cutout (sealed, of course) to prevent exceeding that rating. Even if the cutout were to operate, it should still be well within design limits.

William

 

[aolalde]

For Division 2 locations the NEC allows the use of non explosion proof enclosures, as far as sparking devices are not installed.
Motor operations with adecuate overload protection will prevent development of high temperature.
For details consult the National Electric Code NFPA 70.