Gardner Denver L55, User And Service Manual

Page: 25 / 64

August 20, 2018 23
Automatic operation (open-close operation)
·
When the pressure reaches the upper switching
point set on the system pressure sensor (- 28 -
(B1)), solenoid valves (- 19 - (Y1) and - 20 - (Y4))
are de-energized.
·
The pressure control valve (- 2.2 -) closes.
·
This is due to the fact that the lower control
chamber of the actuator (- 2.1 -) is unloaded by the
de-energized solenoid valve (-19 - (Y1)), and the
upper control chamber and the compression spring
in the actuator (-2.1-) and are pressurized.
·
The screw compressor (- 4 -) is now running in the
offload mode.
·
The pressure reservoir (- 6 -) is unloaded to off-load
pressure (residual pressure).
·
The cooling fan motor (- 25 -) is switched on or off in
dependence upon the final compression
temperature (only air-cooled units).
·
The cooling water solenoid valve (-34-(Y6)) is
opened and closed depending on the compression
end temperature (only water-cooled units).
·
If the pressure at the system pressure sensor
(- 28 - (B1)) does not fall to the set setpoint pressure
within the pre-set motor run-on time (e.g. 20
seconds), the drive motor (- 3 -) is shut down and
the system unloaded to atmospheric pressure.
·
The system is now in the
„stand-by“ mode and can
re-start at any time when the network pressure falls
to the set setpoint pressure (see section
„starting
the system
“).
·
If the pressure at system pressure sensor (- 28 -
(B1) falls to the setpoint pressure before the pre-set
motor run-on time has elapsed, the solenoid valves
(- 19 - (Y1) and - 20 - (Y4) ) are again energized.
·
The unit now changes over to on-load operation.
Stopping the system
·
To de-energize the solenoid valves (- 19 - (Y1)
and - 20 - (Y4) ) press the OFF push-button on the
keypad of the compressor control
GD Pilot TS .
·
The pressure control valve (- 2.2 -) in the suction
regulator (- 2 -) closes and the pressure reservoir is
unloaded to atmospheric pressure.
·
After 30 seconds, the drive motor (- 3 -) and the
cooling fan motor (-25 -) are shut down. The cooling
water solenoid valve (-34- (Y6)) de-energizes and
closes (only water-cooled units).
5.5.2 System control L55RS-L75RS
Standstill of the system
·
If the plant is shut down, the suction controller (- 2 -)
is closed by a pressure spring at the adjusting
cylinder (- 2.1 -).
·
The solenoid valves (- 19 - (Y1) and - 20 - (Y4)) are
de-energized.
·
The pressure reservoir (- 6 -) is unloaded to
atmospheric pressure by means of the solenoid
valve (- 20 - (Y4)) and the actuator (-2.1-).
·
The cooling water solenoid valve (-34-(Y6)) is
closed in a de-energized state (only water-cooled
units
)
Starting the system
·
The drive motor (- 3 -) starts up.
·
The cooling water solenoid valve (-34-(Y6)) is
supplied with power and opens (only water-cooled
units).
·
The suction regulator (- 2 -) is closed.
·
The compressor aspires a certain amount of air
through a bypass line with check valve. Pressure
builds up in the reservoir.
·
Oil is supplied to the screw compressor (- 4 -) due to
the pressure differential between the pressure
reservoir (- 6 -) and the place of injection in the
screw compressor (- 4 -).
·
After a preset time, solenoid valves (- 19 - (Y1) and
- 20 - (Y4)) perform a switching operation, since
they are energized.
·
The air circulating in the system flows through
solenoid valve - 19 - (Y1)) into the lower control
chamber of the actuator (- 2.1 -)
·
The upper control chamber of the actuator (-2.1-) is
isolated from the pressure vessel (- 6 -) by the
solenoid valve (- 20 - (Y4)) and is bled into the
intake channel.
·
The pressure control valve (- 2.2 -) in the suction
regulator (- 2 -) opens.
·
At a reservoir pressure of approx. 65 PSI the
minimum pressure and non-return valve (- 15 -)
opens.
·
Compressed air is now delivered into the consumer
network.
·
The system is now in load running mode.