9065CT9701R03/21

Service Factor

NEMA standards for motors list service factors of 1.15–1.25 for general-purpose AC motors from 1/2 to 200 horsepower. Other motors, such as totally enclosed, fan-cooled, and motors over 200 horsepower have a standard 1.0 service factor. Given the established standards, the service factor cannot be determined without checking the information on the motor nameplate. For this reason, all the thermal unit selection tables in this catalog are designed for 1.15–1.25 service factor motors, except the tables for Class 8198 High Voltage Starters.

The Class 8198 High Voltage Starters tables are designed for 1.0 service factor. It is important to know when a motor has a service factor of 1.0, because failure to do so will result in an oversized thermal unit selection and reduced motor protection.

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