Identifying Unmarked Terminals of a PSC/CSR Motor

Sometimes the terminals on a single-phase compressor are not marked or are hard to identify. The terminals can be identified using a VOM/DMM to measure the resistance of the motor windings. The procedure is provided in the detailed procedure at the end of this section and briefly described below.

First, use the VOM/DMM to find the two terminals across which the highest resistance is measured. These are the run (R) and start (S) terminals. The remaining terminal is the common (C ) terminal. Next, put one lead of the VOM/DMM on the common (C ) terminal, then put the other lead on one o f the other two remaining terminals to find the highest resistance. This is the start winding (S) terminal. The remaining terminal is the run winding (R) terminal.

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