How does Service Factor (S.F.) Apply To A
To determine the service factor horsepower
of a motor, multiply the nameplate horsepower (not amperage) by the
service factor. For example, if a 1/2 Hp motor has a service factor
of 1.6, the motor's service factor maximum horsepower is:
(0.5 HP) x (1.6 S.F.)
= 0.8 Hp.
Likewise, a 10 Hp motor with a nameplate
service factor of 1.15, as shown in example 1, has a service factor
If maximum horsepower of:
(10 HP) x (1.15 S.F.)
= 11.5 Hp
Franklin Electric submersible motors have
service factors in agreement with NEMA guidelines for "pump
motors". Table I lists the service factors and horsepower ratings
for Franklin's 60 Hz submersible motors. 50 Hz submersible motors
generally have a service factor rating of 1.0.
How Does Service Factor Relate to Motor
Franklin 60 Hz motors typically show two
amperage values on the nameplate and in the specification sections
of the Application Installation Maintenance (AIM) manual. The first
value labeled "amps" or "rated input amps" is the expected running
amps when the motor is operated at rated voltage and nameplate
horsepower loads. The second value labeled "SF Max Amps" or "Max A"
is the expected running amps when the motor is operated at rated
voltage and service factor horsepower loads.
Even though amps may increase slightly when
input voltage is higher or lower than nameplate voltage, the motor
amp reading remains the simplest indicator of motor load. your
motor amp reading is higher than nameplate service factor amps, the
horsepower load probably exceeds the service factor horsepower