THREE PHASE SCROLL COMPRESSOR START UP INFORMATION
Scroll compressors, like several other types of compressors, will only compress in one rotational direction. Direction of rotation is not an issue with single phase compressors since they will always start and run in the proper direction.
However, three phase compressors will rotate in either direction depending upon phasing of the power. Since there is a 50-50 chance of connecting power in such a way as to cause rotation in the reverse direction, verification of proper rotation must be made. Verification of proper rotation direction is made by observing that suction pressure drops and discharge pressure rises when the compressor is energized. Reverse rotation also results in an elevated sound level over that with correct rotation, as well as, substantially reduced current draw compared to tabulated values.
Verification of proper rotation must be made at the time the equipment is put into service. If improper rotation is corrected at this time there will be no negative impact on the durability of the compressor. However, reverse operation for over one hour may have a negative impact on the bearing due to oil pump out.
NOTE: If compressor is allowed to run in reverse rotation for several minutes the compressor’s internal protector will trip.
All three phase ZR*3 compressors are wired identically internally. As a result, once the correct phasing is determined for a specific system or installation, connecting properly phased power leads to the same Fusite terminals should maintain proper rotation direction.
The direction of rotation of the motor may be changed by reversing any two line connections to the unit.
SEQUENCE OF OPERATION
COOLING – Circuit R-Y makes at thermostat pulling in compressor contactor starting the compressor and outdoor motor. The G (indoor motor) circuit is automatically completed on any call for cooling operation, or can be energized by manual fan switch on subbase for constant air circulation.
HEATING – A circuit R-W1 is completed on each heating cycle energizing electric heat if so equipped.
START UP NOTES
For improved start up performance, wash the indoor coil with dishwasher detergent
COMPRESSOR CONTROL MODULE
The compressor control is an anti-short cycle/lockout timer with high and low pressure switch monitoring and alarm output.
ADJUSTABLE DELAY-ON-MAKE AND BREAK TIMER
On a call for compressor operation the delay-on-makeperiod begins which will be 10% of the delay-on-breaksetting. When the delay-on-make is complete and the high pressure switch (and low pressure switch if employed) is closed, the compressor contactor is energized. Upon shutdown the delay-on-break timer starts and prevents restart until the delay-on-break and delay-on-make periods have expired.
HIGH PRESSURE SWITCH AND LOCKOUT SEQUENCE (Standard Feature)
If the high pressure switch opens, the compressor contactor will de-energize immediately. The lockout timer will go into a soft lockout and stay in soft lockout until the high pressure switch closes and the delay-on-make time has expired. If the high pressure switch opens again in this same operating cycle the unit will go into manual lockout condition and the alarm circuit will energize. Recycling the wall thermostat resets the manual lockout.
LOW PRESSURE SWITCH, BYPASS, AND LOCKOUT SEQUENCE
NOTE: The low pressure switch is an optional control and the bypass and lockout sequence are part of the standard compressor control module.
If the low pressure switch opens for more that 120 seconds, the compressor contactor will de-energize and go into a soft lockout. Regardless the state of the low pressure switch, the contactor will reenergize after the delay-on-make time delay has expired. If the low pressure switch remains open or opens again for longer than 120 seconds the unit will go into manual lockout condition and the alarm circuit will energize. Recycling the wall thermostat resets the manual lockout.
