If the service factor for a motor is not provided on the nameplate, what is the assumed service factor?

When the service factor for an electric motor is not listed on the nameplate, it is standard practice in the industry to assume a service factor of 1. This value indicates that the motor can safely operate at its rated capacity without experiencing undue stress or risk of failure. A service factor of 1 means the motor is designed to handle loads equal to its rated horsepower continuously under normal operating conditions.

Assuming a service factor of 1 ensures that the motor will perform reliably within its designed specifications. If a higher service factor were assumed without proper justification, it could lead to overloading the motor, risking damage or reduced lifespan. Conversely, a lower service factor could underutilize the motor's capabilities, leading to inefficiencies. Therefore, the convention of using a service factor of 1 in the absence of specific information is critical for ensuring safety and reliability in the operation of electric motors.