York YCAS0130 manual 126

Micro Panel Contents

Internally, the (3) on-board C.T.s and internal circuitry allow the Motor Protection Module to protect against high motor current as programmed on the Motor Pro- tector dip switches. These switches are set at the factory according to motor specifications.

The module also provides phase rotation protection to as- sure the screw compressor does not rotate backwards. A single phase protection circuit located in the module also monitors for a phase imbalance. If phase to phase current imbalance exceeds the 17-25% average imbal- ance thresholds internally set in the module, the Motor Protector will shut the system down.

Whenever the Motor Protection Module senses a fault, internal contacts M1-M2 will open, and shut the system down. These contacts are wired in series with the com- pressor motor contactor. When the contacts open, the micro will attempt to start the system 2 more times. Since the motor contactor signal path from the Relay Output Board to the motor contactor is broken by the Motor Protection Module contacts, it will lock the system out after 3 faults. The Motor Protection Module must then be reset by removing 115VAC power from the Control Panel using CB3. After the Motor Protector is reset, the individual system SYS switch (S2-S5) must be switched OFF and then ON to reset the microprocessor to allow restart of the system.

Always review the data in the history buffer when faults occur. Since the Micro attempts to restart 2 more times and fails to restart with the M1-M2 contacts open, the Micro will record the last 2 faults of "Low Curr/MP/ HP". Hence, the third (3rd) history buffer will show data related to the true cause. See page 142 for additional fault data.

FORM 201.19-NM1 (204)

Anytime the module faults, a thorough investigation of the problem should be performed before attempting to return the system to operation. Failure to perform this investigation could lead to motor or compressor failure. Always record the number displayed on the module display before removing power. Additional details on the Motor Protection Module can be found on page 16.

126 YORK INTERNATIONAL