Control System, Functional Description- Supervisor - Sullair LS-100L Operator's Manual

delivers compressed air to the service line. From
this point on, the line air pressure is continually
monitored by a line pressure gauge and a pressure
switch usually set at 135 psig (9.3 bar). The pres-
sure regulator and the solenoid valve remain closed
during this phase. The inlet valve remains fully open
for maximum capacity.
MODULATING MODE - 125 TO 135 PSIG (7.9 TO
9.3 BAR)
If less than the rated capacity of compressed air is
being used, the service line pressure will rise above
125 psig (8.6 bar). The pressure regulator valve
gradually opens, applying air pressure through the
control line to the inlet valve piston. This causes the
inlet valve to partially close reducing the amount of
air entering the compressor until it matches the
amount of air being used. The control system func-
tions continually in this manner, between the limits
of 125 to 135 psig (8.6 to 9.3 bar), in response to
varying demands from the service line.
The pressure regulator has an orifice which vents a
small amount of air to the atmosphere when the
pressure regulator controls the inlet valve. The ori-
fice also bleeds any accumulated moisture from the
control lines.
UNLOAD - IN EXCESS OF 135 PSIG (9.3 BAR)
LINE PRESSURE
When no air is being used,the service line pressure
rises to the setting (cut-out pressure) of the pres-
sure switch. The pressure switch opens, interrupt-
ing the electrical power to the solenoid valve. At this
time, the solenoid valve allows dry sump tank air
pressure or service air pressure through a shuttle
valve to be applied directly to the inlet valve piston
and keep it closed. Simultaneously, the solenoid
valve sends a pneumatic signal to the blowdown
valve. The blowdown valve opens the sump to the
compressor intake reducing the sump pressure to
approximately 25 to 27 psig (1.7 to 1.9 bar). The
check valve in the air service line pressure prevents
line pressure from returning to the sump.
When the line pressure drops to the low setting (cut-
in pressure) of the pressure switch (usually 125 psig
[8.6 bar]), the pressure switch closes, re-energizing
the 3-way solenoid valve and allowing the blow-
down valve to close. The re-energized solenoid
valve again prevents pressure from reaching the
inlet valve. The inlet valve is fully open and the com-
pressor delivers full rated capacity. Should the pres-
sure begin to rise, the pressure regulator will
resume its normal function as previously described.
To accommodate varied periods of time when there
are not any air requirements, "Dual-Control" is uti-
lized. This feature allows you to set the compressor
in an automatic position whereby the compressor
will shut down when no compressed air requirement
is present and restart as compressed air is needed.
2.7 CONTROL SYSTEM, FUNCTIONAL DESCRIP-
TION- SUPERVISOR II
Refer to Figure 2-4. The purpose of the compres-
sor Control System is to regulate the amount of air
being compressed to match the amount of com-
pressed air being used. The Capacity Control
System consists of a solenoid valve, regulator
valve and an inlet valve. The functional description
of the Control System is described below in four dis-
tinct phases of operation. The following description
text applies to all LS-100 Series compressors with
optional Supervisor II. For explanatory purposes,
this description will apply to a compressor with an
operating range of 125 to 135 psig (8.6 to 9.3 bar).
A compressor with any other pressure range would
operate in the same manner except stated pres-
sures.
START MODE - 0 TO 50 PSIG (0 TO 3.5 BAR)
When the compressor "
depressed, the sump pressure will quickly rise from
0 to 50 psig (0 - 3.4 bar). The compressor initially
starts unloaded, then switches to full load when full
rpm has been achieved. During this period, both
the pressure regulator and the solenoid valve are
closed, the inlet valve is fully open and the com-
pressor pumps at full rated capacity. The rising
compressor air pressure is isolated from the service
line in this phase by the minimum pressure valve
set at approximately 50 psig (3.4 bar).
FULL LOAD MODE - 50 TO 125 PSIG (3.4 TO 8.6
BAR)
When the compressed air pressure rises above 50
psig (3.4 bar), the minimum pressure valve opens
allowing compressed air to flow into the service line.
From this point on, the line air pressure is continu-
ally monitored by the Supervisor II. The pressure
regulator and the solenoid valve remain closed dur-
ing this phase. The inlet valve is in the fully open
position as long as the compressor is running at
125 psig (8.6 bar) or below.
MODULATING MODE - 125 TO 135 PSIG (8.6 TO
9.3 BAR)
If less than the rated capacity of compressed air is
being used, the service line pressure will rise above
125 psig (8.6 bar). The pressure regulator valve
Section 2
DESCRIPTION
" (START) pad is
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