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9.11.3 Low pressure safety (Auto reset)
The low pressure safety switch protects the compressor against deep vacuum operation, a potential cause of failure
due to internal arcing and also operation outside the compressor limits.
The low pressure safety cut out should never be set below the settings as shown in the following table.
Refrigerant
R404A
R134a
Application
M*
L*
M*
Cut out (bar g)
1.0
0.1
0.6
Cut out (psi g)
14.5
1.5
9.0
* M: Medium temperature; L: Low temperature
The low pressure cut out pressure is the setting of cut in minus the differential.
9.12 Wiring
The unit must be isolated from power supply prior to installation. In order to ensure the safety of the installation
and its smooth operation, it is necessary to:
•
Verify the installation is compatible with the wiring diagram.
•
Select the motor circuit breaker by using the maximum continuous current. Refer
Section 4
.
•
Size the wiring for the connection (power and control circuit) according to the properties of the installed
unit.
•
Protect and earth the electrical power supply.
•
Carry out electrical connections according to the norms of the respective country.
•
Secure the cable from touching hot parts and sharp edges with cable clamps.
•
Close the electrical box after completion of the wiring.
9.13 Commissioning of the Condensing Unit
Make sure all isolation valves are fully open before starting the system for the first time. The shut off valve on the
condensing unit could found on outlet of liquid receiver, inlet and outlet of condensing unit.
Important Note
There must be no more than 12 compressor starts per hour. A higher number of
starts reduce the service life of the compressor. If necessary, use an anti-short-cycle
timer in the control circuit.
It is recommended minimum 2 minutes run in time and 3
minutes idle time for each start and stop of the compressor. The compressor may
run in shorter interval during pump down cycle.
