Tecumseh AH5540E - Single-phase Compressor Motor Types

16
SERVICE HANDBOOK
Single-phase Compressor Motor Types
Tecumseh hermetic compressors contain motors designed for specific requirements of starting
torque and running efficiency. There are four general types of single-phase motors, each dis-
tinctly different from the others. Each type of motor may have two to four different configurations
depending on the compressor components.
Resistance Start — Induction Run (RSIR)
This motor, also known as a split-
phase motor, is used on many small
hermetic compressors up through
1/3 HP. The motor has low starting
torque and must be applied to
complete self-equalizing capillary
tube systems such as household
refrigerators, freezers, small water
coolers, and dehumidifiers. This
motor has a high resistance start
winding which is not designed
to remain in the circuit after the
motor has come up to speed (see
Figure 3-1). A relay is necessary to
perform the function of disconnecting
the start winding as the motor comes
up to design speed. Three types of
relays are used with this motor:
•acurrentrelay,
• a wired-in PositiveTemperature
Coefficient (PTC) relay (see Figure
3-2), or
• a module Positive Temperature
Coefficient (PTC) relay.
Capacitor Start — Induction
Run (CSIR)
The CSIR motor is similar to RSIR ex-
cept a start capacitor is included in
series with start winding to produce
a higher starting torque (see Figure
3-3). This is commonly used on com-
mercial refrigeration systems through
¾ HP. Two types of relays are used
with this motor:
•acurrentrelay,or
•apotentialrelay.
Capacitor Start and Run (CSR)
This motor arrangement uses a start
capacitor and a run capacitor in paral-
lel with each other and in series with
the motor start winding (see Figure
3-4). This motor has high starting
torque, runs efficiently, and is used
on many refrigeration and air condi-
tioning applications through 5 HP. A
RSIR motor diagram with current
relay
FIGURE 3-1:
RSIR motor diagram with wired-in
PTC relay
FIGURE 3-2:
CSIR motor diagram
FIGURE 3-3:
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Start Winding
Main Winding
Compressor - Unit
Ground
C
S
R
4 T M Thermal Protector
(115 Volt Only - Neutral)
Line 1
Line 2
Ground
Start Winding
Main Winding
PTC Relay
Compressor - Unit
Ground
Alt. 3/4" Thermal Protector
Control
C
S
R
(115
Volt Only - Neutral
)
(115
Volt Only - Neutral
)
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Start Winding
Main Winding
Compressor - Unit
Ground
S
R
C
Start Capacitor
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Star t Winding
Main Winding
Compressor - Unit
Ground
C
S
R
4 T M Thermal Protector
Identied Conductor
(115 Volt Only - Neutral)
Line 1
Line 2
Ground
Star t Winding
Main Winding
PTC Relay
Compressor - Unit
Ground
Alt. 3/4" Thermal Protector
Control
C
S
R
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Start Winding
Main Winding
Compressor - Unit
Ground
S
R
C
Start Capacitor
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Star t Winding
Main Winding
Compressor - Unit
Ground
C
S
R
4 T M Thermal Protector
Identied Conductor
(115 Volt Only - Neutral)
Line 1
Line 2
Ground
Star t Winding
Main Winding
PTC Relay
Compressor - Unit
Ground
Alt. 3/4" Thermal Protector
Control
C
S
R
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Start Winding
Main Winding
Compressor - Unit
Ground
S
R
C
Start Capacitor
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Start Winding
Main Winding
Compressor - Unit
Ground
C
S
R
4 T M Thermal Protector
(115 Volt Only - Neutral)
Line 1
Line 2
Ground
Start Winding
Main Winding
PTC Relay
Compressor - Unit
Ground
Alt. 3/4" Thermal Protector
Control
C
S
R
(115
Volt Only - Neutral
)
(115
Volt Only - Neutral
)
Line 1
Line 2
Ground
Control
Relay - Current
External Thermal
Protector
Start Winding
Main Winding
Compressor - Unit
Ground
S
R
C
Start Capacitor