Standard Motor Catalog

Section TR Technical Reference Guide

NEMA DESIGN C (1-200 Hp)

Figure 11: Typical NEMA Design C Speed/Torque Curve

GE Types:


Starting Current: Starting Torque: High Breakdown Torque: Normal Full-Load Slip: Low

Figure 9: Line Current vs. Safe Stall Time for Standard Induction Motors

Low (less than 5%)

Motor protection, either inherent or at the motor control should be selected to limit stall time of the motor. POLYPHASE MOTORS, 1-500 Hp NEMA has designated several specific types of motors, each type having unique speed/torque relationships. These designs are described below along with some typical applications for each. Following these descriptions is a summary of performance characteristics. NEMA DESIGN A & B [1-200 Hp (250 Hp-500 Hp, for 2 & 4 Pole only)]


Hard-to-start loads such as plunger pumps, conveyors and compressors.

NEMA DESIGN D (1-150 Hp)

Figure 12: Typical NEMA Design D Speed/Torque Curve

GE Types:


Starting Current: Starting Torque: Very High Breakdown Torque: Not Applicable Full-Load Slip: Low

High (5-8%; 8-13%)

Figure 10: Typical NEMA Design A and B Speed/Torque Curve


The combination of high starting torque and high slip make Type KR motors ideal for very high inertia loads and/or for considerable variations in load; e.g., punch presses, shears, cranes, hoists and elevators.

GE Types:


Starting Current:

Design A - High to Medium (not defined by NEMA) Design B - Low

Starting Torque: Normal Breakdown Torque: Normal Full-Load Slip:

Low (less than 5%)


Fans, blowers, pumps, machine tools, or other uses with low starting torque requirements and essentially constant load.


Data subject to change without notice. 02/23 •

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