5
© 2015 Emerson Climate Technologies, Inc.
AE4-1387 R7
are any questions concerning their application, contact
your Emerson Climate Technologies representative.
Discharge Line Thermostat
Figures 1A, 1B
and
1C
show the operating maps
based on refrigerant for the ZS**KAE scroll. Operation
beyond these limits can cause high compression ratios
or excessive internal compressor temperatures. This
will result in overheating the scroll members, causing
excessive wear resulting in premature compressor
failure.
If the system is designed where operation within these
guidelines cannot be guaranteed, then the discharge
line thermostat is required in the compressor control
circuit.
The thermostats have a cut out setting that will insure
discharge line temperatures below the 275°F maximum
limit. It should be installed approximately 6 inches from
the discharge tube outlet. If a service valve is installed
at the discharge tube, the thermostat should be located
5 inches from the valve braze.
Kits have been set up to include the thermostat, retainer,
and installation instructions. These thermostats must
be used with ½” O.D. discharge lines to ensure proper
thermal transfer and temperature control. They work
with either 120 or 240-volt control circuits and are
available with or without an alarm circuit capability.
See
Table 4
for a list of discharge line thermostat kit
numbers.
Pressure Controls
Both high and low-pressure controls are required on all
models. See
Table 5
for set points.
Pump Down Recommendations
All the ZS**KAE scrolls have an internal spring loaded
low-leak discharge check valve suitable for pump down
application. This valve prevents system pressures from
equalizing and pump down can be achieved. However,
during laboratory testing, we have observed a potential
short cycling condition on the ZS09KAE through
ZS33KAE models. This phenomenon can be attributed
to several factors:
1. Location of low-pressure control sensor. If it is
located right at the suction inlet of the compressor,
it will be more sensitive to pressure spikes.
2. Actual low-pressure setting. Refer to our
recommended setting in
Table 5.
If the differential
pressure setting is too close, this will increase the
possibility of short cycling.
3. Type of Low-pressure control can have an effect
on cycling. The encapsulated non-adjustable type
is more susceptible to causing excessive cycling
due to tolerances.
4. If short cycling cannot be avoided, using a 3-minute
time delay will limit the cycling of the compressor
to an acceptable level.
IPR Valve
Refrigeration scroll compressors (1.3 - 4.5 hp) ZS09-
33KAE have internal pressure relief valves, which open
at a discharge to suction differential pressure of 375
to 450 psi. This action will trip the motor protector and
remove the motor from the line.
Internal Temperature Protection
Refrigeration scroll compressors (1.3 - 4.5 hp)
ZS09-33KAE incorporate a thermo disc which is a
temperature-sensitive snap disc device located at the
muffler plate port. It is designed to open and route hot
discharge gas back to the motor protector thus removing
the compressor from the line.
Motor Protection
Conventional inherent internal line break motor
protection is provided.
Oil Types
Polyol ester lubricants must be provided if the scroll
compressor is to be used with HFC refrigerants. See
Form 93-11
for a complete list of all Emerson approved
lubricants.
CAUTION
POE must be handled carefully and the proper
protective equipment (gloves, eye protection,
etc.) must be used when handling POE lubricant.
POE must not come into contact with any surface
or material that might be harmed by POE, includ-
ing without limitation, certain polymers (e.g. PVC/
CPVC and polycarbonate).
Oil Charges
The recommended oil charges for these compressors
are shown in
Table 6
.
