IDENTIFYING UNMARKED SINGLE-PHASE PSC AND CSR MOTOR TERMINALS MEASUREMENT PROCEDURE

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StepExpected Result/Action
15. Turn power ) off. Use the capacitor discharge too! (Figure SP-8-6) to discharge
run capacitors and any other capacitors in the unit. Locate the
cted to the compressor motor windings and start circuit. (Refer
iring diagram.)
The wiring related to the compressor motor and its starting circuit is identified. All
high-voltage capacitors used in the equipment are discharged, including the run
and start capacitors.
16. Isolate the compressor from the remainder of the circuit by disconnecting the
compressor leads from all components, including the run and start capacitors
and start relay.
Compressor leads disconnected from other unit wiring to measure compressor
motor resistance only.
17. Set up the VOM/DMM to measure resistance on the R x 1 ohm scale. Make
sure the meter is zeroed. Measure across the three motor leads to find the
two motor terminals that give the highest resistance reading as shown in
Figure SP-9-19, View A.
The two wires that produce the highest reading are the run and start windings.
The VOM/DMM is reading the combined (series) resistance of the run and start
winding. The remaining wire is connected to the motor C (common) terminal.
Mark this wire as the C terminal. Proceed to step 18 to determine other terminals
through the process of elimination.
18. Connect one lead of the VOM/DMM to the C terminal wire, identified in step
17. Touch the other meter lead to each of the remaining two compressor
motor wires to find the highest resistance as shown in Figure SP-9-19,
View B.
The highest resistance is the S (start) terminal of the compressor motor. The
remaining terminal is the R (run) terminal.

pic1 11 IDENTIFYING UNMARKED SINGLE PHASE PSC AND CSR MOTOR TERMINALS MEASUREMENT PROCEDURE

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