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Electric Motors - IEC and NEMA Standard Torques

IEC and NEMA torque classifications of electrical motors.

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NEMA (National Electrical Manufacturers Association) has classified electrical motors in four different NEMA designs where torque and starting-load inertia are important criteria.

Torques of the IEC Design N motors are in general close to NEMA Design B motors. IEC Design N and NEMA Design B are the most commonly used industrial types.

Torques of the IEC Design H are nearly identical to NEMA Design C.

IEC/NEMA Standard Torques (lb ft)
Power (hp)2 Pole4 Pole
Locked Rotor TorquePull Up TorqueBreak Down TorqueLocked Rotor TorquePull Up TorqueBreak Down Torque
3 170 160 110 110 200 230 180 215 120 150 200 250
5 160 150 110 105 200 215 170 185 120 130 200 225
7.5 150 140 100 100 200 200 160 175 110 120 200 215
10 150 135 100 100 200 200 160 165 110 115 200 200
15 - 20 140 130 100 100 200 200 150 150 110 105 200 200
  • 1 lb ft = 1.356 Nm
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