Electric Motor Service Factor Definition

Most motors have a duty factor of 1 15 for open motors and 1 0 for totally closed motors.

Electric motor service factor definition.

The service factor sf is commonly misunderstood as an allowable overload for electric motors. The americas water systems group serves north and south america. For example the maximum motor load for a 1hp electric motor with a service factor of 1 15 is. The service factor sf is a measure of periodically overload capacity at which a motor can operate without damage.

Service factor is an indicator of the amount of overload a motor can be expected to handle for example a motor with a 1 0 service factor cannot be expected to handle more than its nameplate hp on a continuous basis. The rated horsepower of an ac motor to the rated armature current of a dc motor or. The canadian electrical code defines service factor as a multiplier that when applied to. However motor operation under these conditions leads to many performance issues down the road.

Motor service factor is probably the most misunderstood value on a motor nameplate. As per the standards a motor s nameplate should indicate the service factor as sf. Traditionally totally enclosed fan cooled tefc motors had an sf of 1 0 but most manufacturers now offer tefc motors with service factors of 1 15 the same as on odp motors. Motors of 10 hp and up usually have a service factor of 1 15.

Franklin electric offers a full line of pumping systems to serve a wide variety of clean water applications. In these cases a motor with a service factor of 1 15 can be applied to the rated power. If it is a 1 0 you can run a motor to 100 load if it is 1 15 then it can be loaded to 115 of its rated load. This means that the motor can operate at 100 of its rated power.

To most it seems quite simple. A 1 15 service factor motor can be. The standard which defines the service factor for motors and generators is the mg 1 standard which in turn defines powers and speeds. A motor designed to operate at its nameplate power rating has a service factor of 1 0.

Most hazardous location motors are made with an sf of 1 0 but some specialized units are available for class i applications. To the rated output of a generator. 1 15 x 1 1 15hp anything above this load will certainly result in motor overheating and consequent damage of the ac motor. Likewise for each power and speed the mg 1 standard defines a frame number which is linked to the service factor.

A motor operating continuously at a service factor greater than 1 will have a reduced life expectancy compared to operating at at its rated nameplate horsepower. A motor with a 1 15 service factor can be expected to safely handle infrequent loads to 15 past it s rated horsepower. Some applications require a motor that can exceed the rated power. For example you may find a 100 hp motor with a sf of 1 15 driving a 110 hp load under the incorrect assumption that it tolerates up to 115 hp.