Page 343 - Reciprocating Compressors Operation Maintenance

328 Reciprocating Compressors: Operation and Maintenance

TABLE 5-4
TROUBLESHOOTING GUIDE FOR MOTOR CONTROLS

Problem Possible Cause Solution

Noisy magnet Misalignment or mis- Replace or realign
(humming or loud mating of magnet magnet assembly
buzz) pole faces
Foreign matter on pole Clean (do not file) pole
face (dirt, lint, rust) faces; realign if necessary
Low voltage applied Check system and coil
to coil voltage; observe voltage
variations during startup
Broken shading coil Replace magnet assembly
Failure to pick up Low voltage Check system and coil
and seal in voltage; watch for voltage
variations during starting
Wrong magnet coil or Check wiring, coil no-
wrong connection menclature, etc.
Coil open or shorted Check with an ohmmeter;
when in doubt, replace
Mechanical obstruction Disconnect power and check
for free movement of
magnet and contact assembly
Faulty contacts in the Check switches in
control circuit control circuit for
proper operation
Failure to drop out "Gummy" substance Clean with nonvolatile
or slow dropout on pole faces or solvent, degreasing
magnet slides fluid
Voltage to coil not Shorted seal-in contact
removed (exact cause found by
checking coil circuit)
Worn or rusted parts Clean or replace worn
causing binding parts
Residual magnetism Replace worn magnet
due to lack of air gap parts or accessories
in magnet path
Mechanical interlock Check interlocks for
binding (reversing free pivoting; new
starters) bushing or light lubrication
may be required
Welding contacts Remove power at the source;
check contacts for possible
welding