3 COMPRESSOR MOTOR AND COMPONENT INFORMATION

1 A LOOK AT SERVICE SAFETY. 2. For more free Tecumseh literature please visit 3. COMPRESSOR MOTOR . AND COMPONENT . INFORMATION . I. Single Phase COMPRESSOR MOTOR Types . 16. II. PSC MOTOR Starting .. 18. III. Hermetic COMPRESSOR Thermal Protectors .. 19. IV. COMPRESSOR MOTOR Starting Relays .. 27. V. Selecting Capacitors .. 32. VI. Identification of Terminal Pins .. 34. VII. Fuse and Circuit Breaker Sizing .. 36. COMPRESSOR MOTOR and COMPONENT INFORMATION 15. I. Single Phase COMPRESSOR Alt. 3/4" Thermal Protector MOTOR Types Tecumseh hermetic compressors contain motors 4 T M Thermal Protector designed for specific requirements of starting torque Line 1 Control and running efficiency.

2 There are four general types C. Start winding of single phase motors, each distinctly different from Line 2. Main winding Identified Conductor the others. Each type of MOTOR may have two to four (115 Volt Only - Neutral) S. different configurations depending on the compres- Ground sor components. COMPRESSOR - Unit Ground R. A. Resistance Start Induction Run (RSIR) PTC Relay This MOTOR , also known as a split-phase MOTOR , is Figure 3-2. RSIR MOTOR diagram with wired-in used on many small hermetic compressors up PTC relay. through 1/3 HP. The MOTOR has low starting torque and must be applied to completely self-equalizing capillary tube systems such as household refrigera- B.

3 Capacitor Start Induction Run (CSIR). tors, freezers, small water coolers, and dehumidifi- The CSIR MOTOR is similar to RSIR except a start ers. This MOTOR has a high resistance start winding capacitor is included in series with start winding to which is not designed to remain in the circuit after produce a higher starting torque. This is commonly the MOTOR has come up to speed. A relay is necessary used on commercial refrigeration systems through to perform the function of disconnecting the start 3/4 HP. Two types of relays are used with this winding as the MOTOR comes up to design speed.

4 MOTOR : Three types of relays are used with this MOTOR : a current relay, or a current relay, a potential relay. a wired-in Positive Temperature Coefficient (PTC) relay, or External Thermal a module Positive Temperature Coefficient Control Protector Line 1 C. (PTC). Start winding Main winding External Thermal Protector Control C. Relay - Current Start winding S. Main winding Line 2. Line 1. Relay - Current R. S. Ground Line 2. COMPRESSOR - Unit R Ground Ground Figure 3-3. CSIR MOTOR diagram. COMPRESSOR - Unit Ground Figure 3-1. RSIR MOTOR diagram with current relay.

5 16 Chapter 3. A LOOK AT SERVICE SAFETY. C. Capacitor Start and Run (CSR) This MOTOR may use either: This MOTOR arrangement uses a start capacitor and a an external thermal protector, or run capacitor in parallel with each other and in series with the MOTOR start winding . This MOTOR has an internal thermal protector. high starting torque, runs efficiently, and is used on PSC motors are basically air conditioning compres- many refrigeration and air conditioning applications sor motors and are very common up through 5 HP. through 5 HP. A potential relay removes the start External or Internal capacitor from the circuit after the MOTOR is up to Thermal Protector speed.

6 This MOTOR may use either: Control Line 1 C. Start winding Main winding an external thermal protector, or Line 2. an internal thermal protector. S. Ground External or Internal COMPRESSOR - R. Thermal Protector Unit Ground Run Capacitor Control Line 1 C. Start winding Line 2 Relay - Figure 3-5. PSC MOTOR diagram. Main winding Potential Ground COMPRESSOR - Unit Ground S. R. Thermal Protector Line 1 C. Plug-In C. Start winding Main winding Figure 3-4. CSR MOTOR diagram. Run Capacitor C2 S. PTC. C1 Relay D. Permanent Split Capacitor (PSC) Line 2.

7 N R. Here a run capacitor is in series with the start wind- Ground PTC Starting and ing. Both run capacitor and start winding remain in COMPRESSOR - Protector Package the circuit during start and after MOTOR is up to Unit Ground speed. This normal starting torque MOTOR is suffi- cient for capillary and other self-equalizing systems. Figure 3-6. PSC MOTOR diagram with start assist kit No start capacitor or relay is necessary. For addi- that includes a module PTC relay. tional starting torque, a proper start assist kit may be added (see Figure 3-6).

8 Some start assist kits may include: a wired-in Positive Temperature Coefficient (PTC) relay, or a module Positive Temperature Coefficient (PTC) relay. COMPRESSOR MOTOR and COMPONENT INFORMATION 17. II. PSC MOTOR Starting Minimum starting voltage for the COMPRESSOR Tecumseh Products Company has pioneered in when it is attempting to start (locked rotor) is: encouraging the development of Permanent Split Capacitor COMPRESSOR motors. This type of MOTOR Table 3-7: Minimum Starting Voltage eliminates the need for potentially troublesome and costly extra electrical components (start capacitors Serial Label Voltage Min.)

9 Voltage for Start and potential MOTOR starting relays). (See Figure 115 103. Figure 3-7.). 208 188. 230 207. 230/208 198. External or Internal Thermal Protector 265 239. Control C. Line 1 Start winding Main winding Line 2 Unequalized system pressure: Head and suc- S tion pressures must be equal and not more than Ground 170 psig. Refrigeration metering device (cap COMPRESSOR - R tube or TX valve) should equalize system pres- Unit Ground sures within 3 minutes. Unequal system pres- Run Capacitor sure may be caused by excessive refrigerant Figure 3-7.

10 Circuit diagram for PSC compressors. charge, short cycling thermostat, or system restriction. Circuit breaker or fuse trips: Branch circuit To fully realize the capabilities of this simplified type fuses or circuit breakers sized too small will of COMPRESSOR MOTOR , it is necessary to understand cause nuisance tripping (see Fuse and Circuit its starting and operating characteristics and the Breaker Sizing on page 36). If the fuse or cir- field conditions which can affect it. cuit breaker trips, see Identifying COMPRESSOR Electrical Problems on page 47 for electrical The following conditions affect PSC MOTOR starting: troubleshooting techniques.