Introduction - A.O. Smith ST1302 Manual

Pump Motors

Introduction

The motors discussed in this application mod-
ule are those commonly found on swimming
pools, spas, jetted tubs, home water systems and
other centrifugal pumps. The motors are 48 and
56 frame used to pump water.
MOTOR TYPES
There are five distinct electrical designs which
may be found on some or all of the pumps being
discussed.
1. Split Phase
This type is used extensively in spa, jetted
tub and above ground pool pump applica-
tions. Some are used on the lower end of in
ground pool and jet pumps. This design has a
start winding and start switch, but no capaci-
tors.
2. Capacitor Start
This is the most common single phase motor
found on in ground pool and jet pump appli-
cations. The starting torque is higher (150-
175% of full load) and starting current lower
than the split phase equivalent. The opera-
tion is similar to the split phase in that there
is a start switch to take the start winding
and capacitor out of the circuit once the
motor reaches 2/3 to 3/4 of full speed.
3. Permanent Split Capacitor (PSC)
This design does not have a start switch, but
uses a run capacitor that remains in the cir-
cuit at all times. However, the run capacitor
is more expensive than a start capacitor, and
the PSC design has only approximately 40%
of the starting torque of a capacitor start
design.
Level 2
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