COMPRESSOR MOTOR GROUNDED WINDING MEASUREMENT PROCEDURE
|12. Check the compressor motor for grounded windings as follows:|
Set up the VOM/DMM to measure resistance on the R x 10,000 ohm scale.
Connect one lead of the VOM/DMM to a good ground connection, such as the
compressor body or compressor discharge/suction line (Figure SP-9-16).
Poor electrical contact because of a coat of paint, layer of dirt, or corrosion
can cause an inaccurate measurement and hide a grounded winding. Touch
the other meter lead to each of the motor leads, one lead at a time, and
observe the meter indication.
|VOM/DMM indicates infinity or high resistance. If a resistance reading is
indicated, it should not be less than 1,000 ohms per volt. For example, on a 230-
volt motor, the resistance should not be less than 230,000 ohms (230 volts x
1,000 ohms/volt = 230,000). A high resistance indicates that the motor windings
are not grounded. Proceed to step 13 (single-phase PSC/CSR compressor) or step
14 (three-phase compressor) to check motor windings for partially shorted
VOM/DMM indicates low or zero resistance, or a measurable resistance that is
less than 1,000 ohms per volt. This may indicate that the motor windings are
grounded. Before replacing the compressor, refer to the caution below.
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