AE4-1311 R2
March 2007
ZPS and ZRS Modulating Scroll
Introduction
The two step modulated scroll is based upon the
very successful ZR16K4 to ZR61K3 single capacity
scroll. Typical Model Numbers are ZRS43K4-PFV
(R-22) or ZPS40K4E-PFV (R-410A).
The basic scroll design has been modified with the
addition of an internal unloading mechanism that
opens a by-pass port in the first compression pocket,
effectively reducing the displacement of the scroll.
The opening and closing of the by-pass port is
controlled by an internal electrically operated
solenoid. See Fig. 1. The ZPS/ZRS modulated scroll
uses a single step of unloading to go from full
capacity to approximately 67% capacity. See Fig. 2.
A single speed, high efficiency motor continues to
run while the scroll modulates between the two
capacity steps. More technical information is
available in the “Online Product Information” section
at www.emersonclimatecustomer.com.
for R-22 must be followed for this compressor,
including recommendations for system testing as
outlined by the “Application Diagram”. The
modulated scroll has standard internal protection
such as an IPR valve and inherent motor protector
®
but does not have the Thermodisc high discharge
temperature protection. These internal protection
devices are described in AE Bulletin 4-1331 and 41312.
There are a few important differences outlined below
that must be observed when designing a system with
the two step scroll.
Operating Envelope
In most respects the two step modulated scroll will
operate like a standard scroll in both the high and
low capacity mode. The basic application guidelines
in Application Bulletin 4-1331 for R-410A and 4-1312
The maximum operating condensing pressure varies
for the ZPS and ZRS scrolls. Please see Figure 3
and Chart 1 for condensing pressure limits
The
maximum condensing limit is the point where the
compressor can still run with a low supply voltage of
197 for the -PFV (208-230 volt) and -10% for all
other motors. The ZPS and ZRS scrolls can operate
at both full- and part-load capacity throughout the
entire operating envelope shown in Figure 3.
Figure 1
Figure 2
Application Considerations
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© 2007 Emerson Climate Technologies, Inc. Printed in the USA.
Figure 3
CHART 1
Model
Max CT
Charge
Limit *
Lbs/kg
Frame
Size*
ZPS20K4E
140°F/60°C
9.6/3.6
63
ZPS26K4E
145°F/63°C
9.6/3.6
63
ZPS30K4E
140°F/60°C
9.6/3.6
63
ZPS35K4E
145°F/63°C
9.6/3.6
63
ZPS40K4E
140°F/60°C
9.6/3.6
63
ZPS51K4E
140°F/60°C
12.0/4.5
70
ZPS60K4E
145°F/63°C
12.0/4.5
70
ZRS43K4
150°F/65°C
9.6/3.6
63
ZRS52K4
140°F/60°C
12.0/4.5
70
Figure 4
* See AE bulletins 4-1312 & 4-1331, Table 5, for explanation.
2
© 2007 Emerson Climate Technologies, Inc. Printed in the USA.
AE4-1311 R2
Capacity Control
The compression process of a scroll is described in
AE Bulletin 4-1312, Figure 7. At any point in the
compression process, there are several pockets
within the scroll that are compressing gas.
Modulation is achieved by venting a portion of the
gas in the first suction pocket back to the low side of
the compressor thereby reducing the effective
displacement of the compressor. See Figure 2. Full
capacity is achieved by blocking these vents, thus
increasing the displacement to 100%. A dc solenoid
in the compressor, controlled by a rectified external
24 volt ac signal, moves the slider ring that covers
and uncovers these vents. The vent covers are
arranged in such a manner that the compressor
operates somewhere around 67% capacity when the
solenoid is not energized and 100% capacity when
the solenoid is energized. The loading and unloading
of the two step scroll is done “on the fly” without
shutting off the motor between steps. See wiring
diagram Fig. 4. The unloaded mode default was
chosen for two reasons:
1.
It is expected that the majority of run hours will
be in the low capacity, unloaded mode.
2.
It allows a simple two-stage thermostat to
control capacity through the second stage in
both cooling and possibly heating if desired.
Unloader solenoid
Standard wiring without Comfort Alert Module
A nominal 24-volt direct current coil activates the
internal unloader solenoid. The input control circuit
voltage must be 18 to 28 volt AC. The coil power
requirement is 20 VA. The external electrical
connection is made with a molded plug assembly
529-0061-00. This plug contains a full wave rectifier
to supply direct current to the unloader coil.
Unloader Test Procedure
If it is suspected that the unloader is not working, the
following methods may be used to verify operation.
1. Operate the system and measure compressor
amperage. Cycle the unloader on and off at ten
second intervals. The compressor amperage
should go up or down at least 25 percent (1).
2. If step one does not give the expected results
shut unit off. Apply 18 to 28 volt AC to the
unloader molded plug leads and listen for a click
as the solenoid pulls in. Remove power and
listen for another click as the unloader returns to
its original position.
3. If clicks can’t be heard, shut off power and
remove the control circuit molded plug from the
compressor and measure the unloader coil
resistance. The resistance should be 32 to 60
ohms depending on compressor temperature.
4. Next check the molded plug.
Voltage check: Apply control voltage to the plug
wires (18 to 28 volt ac). The measured DC
voltage at the female connectors in the plug
should be around 15 to 27 VDC.
Resistance check: Measure the resistance from
the end of one molded plug lead to either of the
two female connectors in the plug. One of the
connectors should read close to zero ohms while
the other should read infinity. Repeat with other
wire. The same female connector as before
should read zero while the other connector again
reads infinity. Reverse polarity on the ohmmeter
leads and repeat. The female connector that
read infinity previously should now read close to
zero ohms.
Replace plug if either of these test methods
doesn’t show the desired results.
Wired with Comfort Alert Module
Please read Form No. 2004ECT-208 to understand
the functioning of this module. The Comfort Alert
module, part number 543-0033-00, is a diagnostic
tool that is installed separately in the electrical box of
the unit. It monitors and analyzes the status of the
scroll compressor and detects and communicates
any system or compressor problems without using
external sensors that would have to be installed into
the system. Any faults are translated through a
blinking LED that can guide the technician quickly
and accurately to the root cause of a problem.
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© 2007 Emerson Climate Technologies, Inc. Printed in the USA.
AE4-1311 R2
One of the advantages of using this module with the
modulating compressor is that the rectifier, which is
located in the modulating coil external power plug, is
not used but is now in the module itself. This means
the plug used with the module, part number 5290369-00, is an ordinary two wire plug and therefore
less expensive. This module will always start the
compressor unloaded and keep it unloaded for five
seconds even when the second stage of the
thermostat is calling for more capacity, a definite
starting advantage under low voltage conditions.
Unloader Test Procedure with 543-0033-00
Comfort Alert Module
If it is suspected that the unloader is not working, the
following methods may be used to verify operation.
1. Operate the system and measure compressor
amperage. Cycle the unloader on and off at ten
plus second intervals by applying and removing
Y2 voltage to the module. Wait five seconds after
power is applied to Y2 before taking a reading.
The compressor amperage should go up or
down at least 25 percent(1).
2. If step one does not give the expected results
remove the solenoid plug from the compressor
and with the unit running and the thermostat
calling for Y2 to be energized test the voltage
output at the plug with a dc voltmeter. The
reading here should be 4 to 18 volts. If not,
unplug the harness from the module and check
voltage at the “DC Sol” pins of the module.
Please refer to “Comfort Alert Ultra Tech
Diagnostics” manual, Form #2004ECT-208,
available on-line. The module will not power the
unloader solenoid if the compressor is not
running or fault code 1 or 9 is active.
3. If the correct DC voltage is at the control circuit
molded plug measure the unloader coil
resistance. The resistance should be 32 to 60
ohms depending on compressor temperature. If
the coil resistance is infinity, much lower than 32
ohms, or is grounded the compressor must be
replaced.
(1) A saturated condensing temperature below
80°F (27°C) may not produce as wide a
change in amperage.
UNLOADER SOLENOID PLUG
529-0061-00
WITH RECTIFIER
529-0062-00
WITHOUT RECTIFIER. USE
WITH 543-0033-00 MODULE.
Safety Control Requirements
High Pressure Control: Installing a high pressure
control in the system is optional with this product. If
a high pressure control is used in the system it is
recommended that a manual reset control be used,
since it is very rare that the condition that caused the
control to trip will correct itself without service
intervention. The recommended cutout should be no
2
higher than 425 psig (30 kg/cm ) for R-22 and 645
2
psig (45 kg/cm ) for R-410A.
Low Pressure Control: A low pressure control is
mandatory and must be installed in the system for
loss-of-charge protection on this modulating scroll.
In a system that is very low on charge, the
modulating solenoid will overheat and burn out if
energized. The cut-out should be set no lower than
2
25 psig (1.75 kg/cm ) for R-22 and 50 psig (50
2
kg/cm ) for R410A. An energized unloader coil will
not overheat should the compressor trip on its motor
protector, provided there is proper refrigerant charge
in the system. The low pressure control should be
installed in the common line of the control circuit to
shut off both the unit and the solenoid power.
Discharge Line Thermostat: Some systems, such
as air-to-air heat pumps, may not work with the
above low pressure control arrangement. A
discharge line thermostat set to shut the compressor
off before the discharge temperature exceeds 290°F
(143°C) may have to be used in conjunction with a
low pressure control installed in the liquid line to
achieve the same protection. Mount the discharge
thermostat as close as possible to the compressor
discharge fitting and insulate well. See Figure 5 for
recommended Copeland part numbers.
4
© 2007 Emerson Climate Technologies, Inc. Printed in the USA.
AE4-1311 R2
Start Components
Start Capacitors
Relays
Model
MFD
Volts
Part Number
G.E. p/n
Copeland
p/n
Pick-up
Volts
Drop-out
Volts
Coil
Voltage
ZPS20K4E-PFV
88-108
330
014-0036-03
3ARR3KC3LP
040-0140-08
140-150
40-90
332
ZPS26K4E-PFV
88-108
330
014-0036-03
3ARR3KC3P5
040-0001-79
170-180
40-90
332
ZPS30K4E-PFV
88-108
330
014-0036-03
3ARR3KC5M5
040-0001-62
150-160
35-77
253
ZPS35K4E-PFV
88-108
330
014-0036-03
3ARR3KC3P5
040-0001-79
170-180
40-90
332
ZPS40K4E-PFV
88-108
330
014-0036-03
3ARR3KC3P5
040-0001-79
170-180
40-90
332
ZPS51K4E-PFV
270-324
330
014-0006-10
3ARR3KC3L5
040-0140-08
140-150
40-90
332
ZPS60K4E-PFV
270-324
330
014-0006-10
3ARR3KC3L5
040-0140-08
140-150
40-90
332
ZRS43K4-PFV
88-108
330
014-0036-03
3ARR3KC3P5
040-0001-79
170-180
40-90
332
ZRS52K4-PFV
175-216
330
014-0006-12
3ARR3KC3L5
040-0140-08
140-150
40-90
332
Discharge Thermostat
Part Number
Kit Part No.
Max.
Voltage
Max. Contact
Rating
071-0540-02
998-0540-02
240
5A @ 240V
085-7022-00*
998-7022-02
240
5A @ 240V
*For conduit use.
Figure 5
5
© 2007 Emerson Climate Technologies, Inc. Printed in the USA.