System Control Esm 37-Esm 50 (Fig. 3 B) - Gardner Denver ESM 30 Original User Manual

4. Design and functioning
Automatic operation (open-close operation)
When the pressure reaches the upper switching
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point set on the network pressure sensor (-28 -
(B1)), solenoid valve (- 30 - (Y1)) is deenergised.
The pressure valve (-2.2-) closes because the lower
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control space of the adjusting cylinder (-2.1.-) is
relieved by the deenergised valve (-30-(Y1)) the
upper control space is impinged with pressure via
the valve (-32-).
The oil separator tank is relieved to no-load
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pressure (residual pressure) via the two valves (-31-
and -32-).
The screw compressor is now running in the offload
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mode.
The cooling air ventilator (- 26 -) is switched on or
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off in dependence upon the final compression
temperature.
When the pressure at the network pressure sensor
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(- 28 - (B1)) does not fall to the set lower switching
point within the set motor run-on time (e.g. 120
seconds), the drive motor (- 3 -) and the cooling air
ventilator motor (- 26 -) are shut down and the
system is depressurised to atmospheric pressure.
The system is now in the "stand-by" mode and can
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restart at any time when the network pressure falls
to the lower switching point (see section "Starting of
the system").
When the pressure at the network pressure sensor
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(- 28 - (B1) falls to the preset lower switching point
before the set motor run-on time has elapsed,
solenoid valve (- 30 - (Y1)) is energised again.
The unit now changes over to on-load operation.
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4.5.2 System control ESM 37-ESM 50
(Fig. 3 b)
(See also operating instructions for the compressor
control GD Pilot MK)
Danger
The lower control area of the operating cylinder
(2.1) is generally pressurised (even when the
system is at a standstill). Before working on the
suction regulator this must be bled by carefully
unscrewing the return valve (2.3).
Standstill of the system
During plant standstill the suction regulator (-2)
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should be closed via pressurisation in the lower
control area of the operating cylinder (-2.1-).
Solenoid valves (- 19 - (Y1) and - 20 - (Y4)) are
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deenergised.
The oil separator vessel (-6-) is released via the
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relief valve (-21-) to atmospheric pressure.
Starting the system
The motor starts up in the Y-mode.
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The intake regulator is closed.
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The compressor aspires a certain amount of air
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through a bypass valve. Pressure builds up in the
reservoir.
The oil supply of the screw compressor takes place
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through a drop in pressure between the oil separator
vessel and the injection spot in the screw
compressor.
When switching the drive motor over to Δ-mode,
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switch the solenoid valves (-19-(Y1) and 20 (Y4) as
these are supplied with power.
The air circulated in the system streams over the
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solenoid valve (-20- (Y4)) in the upper control area
of the operating cylinder (-2.1-). The relief valve
(-21-) is closed.
The lower control area of the operating cylinder
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(-2.1-) is blocked and bled by the solenoid valve
(-19- (Y1)) from the oil separator vessel.
The pressure control valve (- 2.2 -) in the intake
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regulator (- 2 -) opens.
At a reservoir pressure of approx. 4.5 bar/65 PSI the
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pressure holding and check valve (- 15 -) opens.
Compressed air is now delivered into the consumer
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network.
The system is now in load running mode.
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