12
13
High Pressure and Low Pressure Cut-out
Settings
A high-pressure control with a maximum cut-out setting
of 28 bar(g) is required. The high-pressure cut-out should
have a manual reset feature for the highest level of system
protection.
The low-pressure cut-out should be set as high as
possible in all applications. For medium temperature
applications the normal minimum is 2.5 bar(g) which
corresponds to -10
o
C with R22 and -16˚C with R404A.
For low temperature applications the minimum cut-
out setting should not be lower than 0.3 bar(g) for a
compressor using R404A, and should not be lower than
0.1 bar(g) for a compressor using R22. The cut-out point
of the LP switch must be set using an accurate suction
pressure gauge rather than the scale on the switch which
is provided for rough setting only.
Warning
Copeland Scroll Fusion compressor should NEVER be
allowed to run in a vacuum.
The low-pressure cut-out should have a manual reset
feature for the highest level of system protection.
Liquid Solenoid Valve
A liquid line solenoid valve is effective in keeping liquid
out of the low side when the system cycles on the
thermostat. The solenoid should be installed close to
the expansion valve to keep the main volume of the
liquid line on the high side of the system during off
periods. All solenoid valves leak slightly and may not
be 100% effective in keeping liquid in the high side
during extended shutdown periods which can occur in
cold rooms used for storing seasonal products. In most
cases, opening and closing the solenoid valve when
the compressor starts and stops provides adequate
protection from liquid migration to the compressor
crankcase.
Liquid Line Insulation
Copeland Scroll™ Fusion compressors have many
characteristics found on two-stage piston compressors,
among them, a cold liquid line after the heat exchanger.
The cold liquid is very important for improving the system
capacity and effi ciency, and any increase in liquid line
temperature after the heat exchanger is a system loss.
The liquid line should therefore be insulated with
tightly-fitted closed cell foam.
The wall thickness of
the insulation should be at least 10 mm for medium
temperature applications and >15 mm for low
temperature applications. In some low temperature
applications, an uninsulated liquid line could even cause
ice formation, and in humid environments condensation
will occur. The line connecting the receiver to the inlet of
the heat exchanger does not require insulation.
Pumpdown Cycle
Pumpdown cycles are widely applied in systems with
reciprocating compressors. Copeland Scroll Fusion
compressors have inherently superior liquid handling
capability, so a pumpdown at each thermostat cycle is
not recommended. A pumpdown cycle before defrost
will be helpful in reducing the defrost time. Copeland
Scroll Fusion
compressors are fi tted with a spring loaded
low-leak check valve under the discharge service valve, so
an external check valve should not be necessary. When
pumpdown fi nishes, the compressor will stop and contain
a very large volume of high pressure gas in the top cap
area. This refrigerant will quickly leak back to suction and
will cause a signifi cant pressure rise that could reset the
low pressure switch. The control circuit should not allow
the compressor to restart; restart should only occur
when the thermostat closes.
Figure 8.
Schematic Diagram
High Pressure and Low Pressure switches must be fi tted
by
the system manufacturer and connected to the pressure
ports shown in the compressor outline drawing on
Figure 6. HP and LP cut-out switches must be electrically
connected as shown in the wiring diagram on Figure 10.
Electrical Installation
The compressor is supplied with a wiring diagram
inside the terminal box cover as shown in Figure
10. Fuses and circuit breakers must be installed in
accordance with local electrical regulations. The
terminal box has an IP54 rating.
Electrical Shock
Conductor Cables! Electrical Shock! Shut Off Power
before High potential testing
The compressor and accessories are tested for leakage to
ground before shipping.
Disconnect the control board
PWR and DEMAND connections to avoid any risk of
damage during high potential testing.
Three-phase Motors
All compressors can be started direct on line only.
Control Board Connection
The control board, which is mounted in the terminal
box, monitors the compressor sensors, protects the
compressor, drives the electronic expansion valve and
displays useful information in a seven segment display.
Three red LEDs indicate the status of the CCC (compressor
contractor coil), Alarm and a relay which is connected
to the black terminal block. The board is powered via
a transformer with a nominal output of 16 VAC. When
correctly wired and powered up the board goes through
a self checking routine and displays a fl ashing 0. If the
display is blank, check the power supply on the PWR, the
transparent fuse, the transformer input and output, and the
white fuse. The transparent fuse (250 V 2A) protects the
transformer and other on-board electronic components.
The white fuse (250 V 1A) protects the system control
circuit and the on-board relays from external short circuits.
Wiring Diagram and Wiring Instruction
The position of the 4-Bit Dip Switch in the terminal box and
the recommended wiring diagrams are shown in Figures 9
and 10.
Warning
CoreSense™ Diagnostics
The CoreSense Diagnostics module in the terminal box
monitors several sensors and protects the compressor
from the following malfunctions:
•
Reverse rotation by oil differential pressure switch
•
Compressor not pumping by oil differential pressure
switch
•
High discharge temperature by discharge port
temperature sensor
•
High oil temperature by oil temperature sensor
•
Low oil level by optical oil level sensor
•
Motor overheat by embedded four thermistors
•
High pressure – cut-out to be connected by system
manufacturer or installer
•
Low pressure – cut-out to be connected by system
manufacturer or installer
Warning
Fusion Control Box Wiring Standard
According to Figure 11, there are 4 joints at the bottom
of the control box. Each joint has dedicated wires to be
assembled. Table 1 explains the function, requirement and
connection method of each joint and wires inside. Wire C,
D and G have been pre-wired in factory. C (Black) and D
(Orange) are for compressor start/stop feedback input,
connecting to “Demand” (Blue) connectors. G (Red) is wire
of power input for Alarm Devices, connecting to “Alarm”
Figure 9.
CoreSense™ Diagnostics Board
TXV:
Thermostatic Expansion Valve
Fusion Standard BOM
VI:
Vapor Injection
EXV:
Electronic Expansion Valve
Note:
Sight glass is provided and installed as standard ex-factory only in
TWD models
(Orange) connector. The wire size for these three pre-
wirings is 18AWG.
Figure 12, on the other hand, shows the recommended
wiring sequence for the control box.
CoreSense Diagnostics module is functioned to record
latest 10 alarm histories. By pushing one button on the
board, the user can check the alarm codes from latest
to distant in sequence on LED display. The display starts
from “H” and ends with “h”. When alarm code is blank,
the display will show “0” instead.
