Product Manual

CHAPTER V
Electrical Characteristics and Connections
Voltage, frequency and phase of power supply should be consistent
with the motor nameplate rating. A motor will operate satisfactorily
on voltage within 10% of nameplate value, or frequency within 5%, or
combined voltage and frequency variation not to exceed 10%.
Voltage
Common 60 hz voltages for single-phase motors are 115 volt, 230 volt,
and 115/230 volt.
Common 60 hz voltage for three-phase motors are 230 volt, 460 volt
and 230/460 volt. Two hundred volt and 575 volt motors are sometimes
encountered. In prior NEMA standards these voltages were listed as 208
or 220/440 or 550 volts. Motors with these voltages on the nameplate
can safely be replaced by motors having the current standard markings
of 200 or 208, 230/460 or 575 volts, respectively.
Motors rated 115/208-230 volt and 208-230/460 volt, in most cases,
will operate satisfactorily at 208 volts, but the torque will be 20% - 25%
lower. Operating below 208 volts may require a 208 volt (or 200 volt)
motor or the use of the next higher horsepower, standard voltage
motor.
Phase
Single-phase motors account for up to 80% of the motors used in
the United States but are used mostly in homes and in auxiliary low-
horse-power industrial applications such as fans and on farms.
Three-phase motors are generally used on larger commercial and
industrial equipment.
Current (Amps)
In comparing motor types, the full load amps and/or service factor amps
are key parameters for determining the proper loading on the motor.
For example, never replace a PSC type motor with a shaded pole type
as the latter’s amps will normally be 50% - 60% higher. Compare PSC
with PSC, capacitor start with capacitor start, and so forth.
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