Readings in the range listed below 100
CAUTION: Megger checks should NEVER be performed on any compressor that is under a vacuum.
COMPRESSOR CONTACTOR
The contactor serves as the voltage supply switch for the compressor circuit. Voltage to the coil of the contactor is supplied by the circuit board.
Check Out:
The two (2)* line supply screws of the contactor should always have supply voltage present when voltage is on to the product.
The other two (2)* screws (load) should have line voltage when the contactor is energized. The contactor coil receives its supply voltage from the circuit board. Should the contactor fail to energize:
Check for supply voltage from circuit board, lead connections to contactor coil, and ohms value of coil.
* (3) if the product is 3 phase
COMPRESSOR & STARTING COMPONENT CHECK-OUT PROCEDURE
When compressors fail to start or run properly, it is normally the external electrical supply or the compressor start components that are defective
1.Check voltage at compressor terminals. NO voltage will require checking the electrical circuit working back from the compressor to determine where the voltage supply is interrupted and correct as required. The load voltage, while compressor is trying to start, should not be less than 90% of rated required voltage.
Line voltage and wire size effect the life expectancy of the electrical components, compressor, motor winding, solenoid coils, etc.
Poor line quality voltage will cause many erratic electrical problems. Remember every electrical product, ice ma- chine, dispenser,
2.A defective capacitor or start relay may prevent the compressor from starting. Should the compressor at- tempt to start, but is unable to do so, or if the compressor hums or trips off on the over protector, check the following:
NOTE: For 50 HZ application on dual rated 50/60 HZ models, load voltage while compressor is start- ing must not be less than 90% of 50 HZ
rating.
Relay
Potential --
For the potential type, contacts are normally closed. The start contacts open by C.E.M.F. generated by the com- pressor at approximately 80% of the normal operating speed. As the contacts open, only the start capacitor is removed from the start circuit. Both the start and run winding and the run capacitor remain in the circuit. This relay may or may not be directional in mounting.
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