Motor Service Factor Explained. The nema (national electrical manufacturers association) standard service factor for totally enclosed motors is 1.0. If the motor in the example from step 2 had a service factor of 1.15 then its overload would be acceptable and the motor could be operated without damage.
Service factors are defined by the american gear manufacturers association (agma), based on the type of gearbox, the expected service duty, and the type of application. Service factor is a multiplier that indicates how much a motor can be overloaded under ideal ambient conditions. Motors that continuously operate at a service factor greater than 1 will have a reduced life expectancy compared to operating at its rated nameplate horsepower.
Service factor represents the motor’s ability to handle these temporary demand increases.
A motor being used for a centrifugal fan is likely to have different starting torque requirement than a conveyor belt. Sizing a gearbox (or gearmotor) for an industrial application typically begins with determining the appropriate service factor. The root mean square load torque (power) requirement must be less than 100% of the rated motor torque (power) and ideally greater than 75% of rated motor torque (power). Check the motor nameplate for a service factor.