Manual 2100-354
Page
19
START UP AND OPERATION
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 24V solenoid coil on reversing valve
controls heating cycle operation. Two thermostat options,
one allowing “AUTO” changeover from cycle to cycle and
the other constantly energizing solenoid coil during heating
season and thus eliminating pressure equalization noise
except during defrost, are to be used. On “AUTO” option,
a circuit is completed from R-W1 and R-Y on each heating
“On” cycle energizing reversing valve solenoid and pulling
in compressor contactor starting compressor and outdoor
motor. R-G also make starting indoor blower motor. Heat
pump heating cycle now in operation. The second
energizes the reversing valve solenoid constantly whenever
the system switch on subbase is placed in “Heat” position,
the “B” terminal being constantly energized from R. A
thermostat demand for heat completes R-Y circuit, pulling
in compressor contactor starting compressor and outdoor
motor. R-G also make starting indoor blower motor.
