Instructions
36 | AN405821998738en-000102 - 118A5495A
© Danfoss | Climate Solutions | 2023.02 | LCA012A024
10.3. Prevention of short cycle operation
Short cycle operations (frequent repetitions of start and stop) could cause a short supply of lubrication
oil as a result of excessive oil level rise at the time of starting. In addition, if a large start current flows
repeatedly through the built-in motor, the motor may overheat, resulting in motor coil burnout.
To prevent the short cycle operation, it is necessary at the minimum to set such that the pattern as
shown at right will be achieved. Major causes of short cycle operation are as follows
• Unbalanced load and condensing unit capacity
• Clogged suction strainer
• Improper setting of the operating pressure value
In addition to the above, where a unit cooler is used, the temperature sensor of inside compartment
temperature regulator may be misplaced (the temperature sensor is blown directly by cold air from the
unit cooler). Adjust the inlet suction superheating degree of condensing unit at 5 – 40 deg.
10.4. Setting the high pressure cut-off
Operation
Room temperature
(
)
Stop
Time
Inside compartment temperature
3 min.
or more
4 min.
or more
7 min.
or more
High pressure cut value (CUT OUT)
140 bar
+0 bar
-10 bar
Fig. 36
10.2. Prevention of reverse phase operation
Compressor of this equipment runs in one direction only. If it is run in reverse direction, the compressor may fail to operate properly.
To prevent the reverse phase operation, the unit is equipped with the reverse phase prevention relay which checks whether the phase of power supply is
positive or reverse and, if it is in the reverse phase, displays the error code “E32”, inhibiting the compressor start.
In such occasion, check that the primary (power supply side) phase and secondary phase are the same phase.
L1 L2 L3 N
L1 L2 L3 N
Primary side
Secondary
Source power
Note:
Turn power off before replacing the connection for prevention of electric shock.
Fig. 35
10.5. Setting of operation control pressure (Setting evaporation temperature)
Setting value of the operation control pressure needs to be adjusted according to purposes. Special care is required particularly on the relation to the
setting value of room temperature (inside compartment temperature) thermostat.
Room temperature (inside compartment temperature) is controlled by opening or closing the liquid solenoid valve with the room temperature (inside
compartment temperature) thermostat. The condensing unit controls its capacity by detecting changes in the suction gas pressure (Ps) by opening or
closing the liquid solenoid valve with the control PCB of condensing unit.
Evaporation temperature* can be set in the unit of °C over a range of 5 to -45°C with the rotary switches (SW1, 2) on the control PCB of condensing unit. The
setting may be changed even during operation of condensing unit.
The low pressure setting at the shipment is "SW1"="0", "SW2"="0"
A guide for setting of pressure value is shown below.
*1 The evaporation temperature means the saturated temperature of suction pressure.