NEMA MG1 Part 30 1

[Farkel]

I don't have the most recent copy of MG1, and would like to know what Part 30 says about a TEFC 200HP, 2 Pole motor in regards to continuous running at 4200RPM.
Regards,
Farkel

 

[macmckim]

Nema MG1 Part 30, point 30.2.2.3 states if you want to operated the motor above its base speed, to consult with the motor manufacture.

 

[electricpete]

NEMA MG-1 2003
"30.2.2.2.4 Motor Torque During Operation Above Base Speed
Above base speed, a motor input voltage having a fundamental component equal to rated motor voltage (which may be limited by the control and its input power) as frequency increases will result in constant horsepower operation (torque reducing with reduced volts per hertz). The maximum (breakdown) torque capability of the motor within this speed range will limit the maximum frequency (and speed) at which constant horsepower operation is possible.

The curves in Figure 30-4 represent the load which the defined motor is capable of carrying above base speed.. The curves represent operation at constant horsepower for 1.0 service factor motors and similar performance for 1.15 service factor motors. The maximum frequency of 90 hertz is established based on the approximate peak torque capability of greater than 175 percent for NEMA Design A, B, and E motors assuming operation at a constant level of voltage equal to rated voltage from 60 to 90 hertz. For the capability of motors for which the minimum breakdown torque specified in 12.39.1 or 12.39.3 is less than 175 percent, consult the motor manufacturer.
For operation above 90 hertz at a required horsepower level, it may be necessary to utilize a motor with a greater horsepower rating at 60 hertz.

However, the maximum speed at which a motor can safely operate may be limited to some speed below the maximum speed related to its load carrying capability because of mechanical considerations (see 30.2.2.3)."

"30.2.2.3 Maximum Safe Operating Speeds
The maximum safe operating speed of a direct-coupled motor at 0–40C ambient temperature should not exceed the values given in Table 30-1. For possible operation at speeds greater than those given in Table 30-1 or conditions other than those stated consult the motor manufacturer. For motors not covered by Table 30-1, refer to 12.53.1 or 20.13."

The table shows a max speed of 3600 for your motor (200hp 2-pole TEFC). Note the table allows speed above nameplate for smaller 2-pole motors below 50hp and also for 4-pole and 6-pole 200hp TEFC, but not for 2-pole 200hp TEFC.

Therefore for your particular motor, operation above 3600 rpm is not permitted except based on consultation with the manufacturer. (same as macmckim said).

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