Champion Compressors Ltd. Manual No. 975203 Rev H
8
The minimum pressure valve maintains pressure in the integrated screw
during start-up and during off-load operation to assist oil circulation. Back-
flow of compressed air from the air mains into the separator is prevented by a
non-return valve which is incorporated in the minimum pressure valve.
5.3 Control System
The purpose of the control system is to regulate the compressor air intake to
match the amount of air being used. The major components of the control
system are the intake controller, solenoid valve and pressure switch.
As the compressor starts (Stop / Start control only) or switches into DELTA (or
run) mode (Star-delta, CSU Only), the solenoid valve is energised, allowing
the air to enter the compressor. The system pressure rises.
The compressor pumps until the pre-set UN-LOAD pressure switch setting is
reached. The pressure switch then de-energises the solenoid valve, closing
the intake valve and allowing the integrated screw to reduce sump pressure.
On the stop/start models (standard on Ci 40, 55, 75) the compressor will
come to a stop. The load/unload models (standard Ci 110) will continue to
unload (producing no air) for a set time, governed by the setting of the run-on
timer, after which the compressor will enter standby mode, ready to
automatically start when air demand exists.
When mains pressure falls to the pre-set LOAD pressure switch setting, the
solenoid valve is energised, signalling for the inlet valve to open, thus allowing
the compressor to build up pressure to the pre-set level again. This cycle
continues as long as air demand is present.
5.4 Operating Temperature
This unit is designed to work from 0°C to temperatures in excess of 40°C.
Where site ambient temperatures will exceed 40°C (for example in a boiler
room), then it is better to duct the cooling air to the compressor. The oil
temperature is regulated by a thermo-bypass valve. For details on thermo-
bypass valve operation refer to Section 8.5.
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