1

HVACR317 – Core for Refrigeration

Motor ApplicationCompressor Motors

2

HERMETIC COMPRESSORS CANNOT BE SERVICED

3

HERMETIC COMPRESSOR CROSS SECTION

4

HERMETIC COMPRESSORS MAY HAVE CURRENT RELAYS FOR MOTOR

STARTING

5

CURRENT RELAYSCLOSE ON HIGH AMPSOPEN ON LOW AMPS

6

MOTOR CURRENT PROFILE

AMPS

APPLIED

MOTOR STARTS

MOTOR SPEED INCREASE MOTOR AT

SPEED

7

MOTOR CURRENT PROFILE

CURRENT RELAY CUT-IN

MOTOR STARTS

CURRENT RELAY CUT-OUT MOTOR AT

SPEED

8

Once the motor is started, the amps level off to FLA (Full Load Amps).

Locked Rotor Amps

(LRA) Full Load Amps (FLA)

AMPS

TIME

AMPS

100%

0%

100%

0%Speed

CURRENT RELAY CUT-IN

CURRENT RELAY CUT-OUT

9

HERMETIC COMPRESSOR WIRING with CURRENT

RELAYS

10

HERMETIC COMPRESSOR WITH CAPACITOR

11

POTENTIAL RELAYS USED TO START ELECTRIC

MOTORS

12

POTENTIAL RELAY APPLICATION

13

POTENTIAL RELAY OPERATION

CURRENT FILLS THE START CAPACITOR AT STARTUP

14

POTENTIAL RELAY OPERATION

CURRENT FILLS THE START CAPACITOR AT STARTUP

15

POTENTIAL RELAY OPERATION

CURRENT BY-PASSES THE START CAPACITOR AFTER MOTOR SPEED

16

POTENTIAL RELAY OPERATION

FLUX LINES BUILD ACROSS THE COIL OPENING THE CONTACTS

17

HARD START KITS FORHART-TO-START

MOTORS

18

CAPACITOR START CAPACITOR RUN MOTOR

CSCR MOTOR

19

MEASURING CURRENT with a CLAMP-ON AMMETER

CURRENT RELAY APPLICATION

POTENTIAL RELAY APPLICATION

20

MEASURING CURRENT with a CLAMP-ON AMMETER

CURRENT RELAY APPLICATION

21

MEASURING RESISTANCE with a MULTIMETER

MOTOR WINDING RESISTANCE

CURRENT RELAY COIL RESISTANCE

22

RESISTANCE MEASUREMENTS ACROSS

MOTOR WINDINGS

LEAD POSITIONS RESISTANCE MEASUREMENT

R to C LOW RESISTANCE

S to C MEDIUM RESISTANCE

HIGH RESISTANCER to S