NEMA A, B, C and D Electrical Motor Design
A comprehensive tool for selecting and comparing NEMA electrical induction motor designs (A, B, C, and D) based on their performance characteristics including slip, starting current, locked rotor torque, and breakdown torque for different applications.
NEMA Motor Design Comparison
NEMA has established four different designs (A, B, C, and D) for electrical induction motors. Different motors with the same nominal horsepower may have different start current, torque curves, speeds and other variables.
Design Characteristics:
NEMA Design A
- Maximum 5% slip
- High to medium starting current
- Normal locked rotor torque
- Normal breakdown torque
- Suited for: fans and pumps
NEMA Design B
- Maximum 5% slip
- Low starting current
- High locked rotor torque
- Normal breakdown torque
- Suited for: HVAC applications with fans, blowers and pumps
NEMA Design C
- Maximum 5% slip
- Low starting current
- High locked rotor torque
- Normal breakdown torque
- Suited for: equipment with high inertia and high starting torques (positive displacement pumps, conveyors)
NEMA Design D
- Maximum 5-13% slip
- Low starting current
- Very high locked rotor torque
- Suited for: equipment with very high inertia starts (cranes, hoists)