A.O. Smith ST1302 Manual page 4

2
ST1302
CAP START/RUN
PT1072
PARTIAL MOTOR
Level 2
4. Capacitor Start/Capacitor Run
This design is used to increase efficiency in
the run mode. Both start and run capacitors
are used.
5. Polyphase (3 Phase)
This is the simplest, most efficient design.
Its use is limited to commercial and industri-
al applications since three phase power is not
available in residential areas.
These same motors may sometimes be applied
to pumps used in other applications where the
selection and troubleshooting procedures are sim-
ilar, but the application has specific considera-
tions due to the fluid being pumped or the oper-
ating environment.
Underwriter's Laboratories has established
safety standards for many pump motors.
Standard 1081 applies to swimming pool motors
and Standard 778 applies to jet pump motors.
The motors are two pole (3450 RPM) designs or
two pole/four pole (1725 RPM) designs. The two
pole design is used because it runs cooler and
moves more water.
Typical pump motors discussed here use ball
bearings at each end of the shaft, one of which is
locked to take any thrust loading. Some pump
motors have had ball/sleeve bearing construction.
Jet pump motors typically have double shielded
bearings and pool pump motors typically have
double sealed bearings. Both types are perma -
nently lubricated and neither type is waterproof.
Some pumps utilize a partial motor where the
pump provides the shaft extension bearing bore.
This type of construction is not popular, and
replacement usage has fallen dramatically. Some
replacement motors are still available. Two basic
types were used in the past. The difference is the
length of the shaft extension.
Pump Motors
A.O.Smith