Manitowoc UG018A, Руководство техника

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33
DIAGNOSING START COMPONENTS
If the compressor attempts to start, or hums and trips
the overload protector, check the start components
before replacing the compressor.
Capacitor
Visual evidence of capacitor failure can include a
bulged terminal end or a ruptured membrane. Do not
assume a capacitor is good if no visual evidence is
present. A good test is to install a known good
substitute capacitor. Use a capacitor tester when
checking a suspect capacitor. Clip the bleed resistor
off the capacitor terminals before testing.
Current Relay
The relay has a set of contacts that energize and de-
energize the compressor start winding. The contacts
on the relay are normally open (start winding de-
energized). When power is applied the run winding will
be at LRA. The relay coil will become an
electromagnet and close the contacts (start winding
energized). As the compressor motor RPM increases,
the run winding current draw and relay coil magnetism
decrease allowing the contacts to open. Replace a
suspect relay with a known good relay, or use a
momentary switch and start capacitor to mimic relay
operation.