Manual 2100-277
Page 16
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 ZR3 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 terminal
should maintain proper rotation direction.
The direction of rotation of the compressor may be changed
by reversing any two line connections to the unit.
CONDENSER FAN OPERATION
The condenser fan motor on 230/208 volt, one and three
phase, 60 HZ units is a two speed motor that comes factory
wired on high speed for peak performance. If ambient
conditions permit, it can be reconnected to low speed (red
wire) for lower sound level. See wiring diagram.
50 HZ models must have fan wired on low speed. These
models are factory wired on low speed.
START UP
IMPORTANT INSTALLER NOTE
For improved start up performance wash the indoor coil
with a dish washing detergent.
CRANKCASE HEATERS
WL421 units are provided with compressor crankcase heat.
WL602 and WL482 units are not provided with crankcase
heat. These units utilize scroll compressors which do not
require crankcase heat in this application.
The WL421 models have an insertion well-type heater
located in the lower section of the compressor housing.
This is a self-regulating type heater that draws only enough
power to maintani the compressor at a safe termperature on
these units.
Some form of crankcase heat is essential to prevent liquid
refrigerant from migating to the compressor causing oil
pump out on compressor start up and possible valve failure
due to compressing a liquid.
The decal in Figure 9 is affixed to all WL421 units detailing
start up procedure. This is very important. Please read
carefully.
HIGH PRESSURE SWITCH
The WL482 and WL602 models are supplied with a remote
reset high pressure switch. If tripped, this pressure switch
may be reset by turning the themostat off then back on
again.
FIGURE 9
STARTING PROCEDURE
IMPORTANT
THESE PROCEDURES MUST BE FOLLOWED AT
INITIAL START UP AND AT ANY TIME POWER HAS
BEEN REMOVED FOR 12 HOURS OR LONGER.
To prevent compressor damage which may result
from the presence of liquid refrigerant in the
compressor crankcase.
1. Make certain the room thermostat is in the “off”
position (the compressor is not to operate).
2. Apply power by closing the system disconnect
switch. This energizes the compressor heater
which evaporates the liquid refrigerant in the
crankcase.
3. Allow 4 hours or 60 minutes per pound of
refrigerant in the system as noted on the unit
rating plate, which ever is greater.
4. After properly elapsed time, the thermostat
may be set to operate the compressor.
5. Except as required for safety while servicing,
Do not open system disconnect switch
.
7961-061
