Section 2
DESCRIPTION
7
Figure 2-2 Encapsulated Compressor System
2.6 CONTROL SYSTEM, FUNCTIONAL DESCRIP-
TION
The purpose of the compressor control system is to
maintain compressor capacity to meet the system
demand.
It consists of an
inlet valve, pressure regulator
valve, solenoid valve, control lines
and the
mo -
tor start selector switch
.
The selector switch has three settings:
MANUAL/
START
,
OFF/RESET
and
AUTOMATIC START/
STOP
.
MANUAL MODE
In the manual mode the ball valveshould beclosed
to isolate the pressure regulator . The compressor
motor will start and the air control solenoid will be
energized (closed.) During this time the inlet valve
is fully open due to inlet air flow, and the compres-
sorwill start todeliver compressed air. When the air
demand isless than the rated flowfor the compres-
sor, the service line pressure will rise to the pres-
sure switch cut---out setting. The system pressure
switch opens, interrupting the electrical power to
thesolenoid valve. Thesolenoid valve opensallow-
ing pressure to be applied totheinlet valve causing
theinletvalvetofullyclose. Thecompressorwill
continue to run (unloaded) until the line pressure
drops to the low setting of the pressure switch --- ---
the pressure switch closes, reenergizing the nor-
mally open solenoid valve and allows the compres-
sor to load again.
MANUAL MODULATION CONTROL MODE
In the modulation control mode the ball valve
should be open to allow pressure to the pressure
regulator. The compressor motor will start and the
system pressure will rise until it reaches the set
point ofthe pressure regulator. The pressure regu-
lator will them begin to open allowing pressure to
be applied to the inlet valve. The pressure regula-
torwill modulate the inlet valve tomatch system de-
mand.
OFF/RESET MODE
The compressor motor, if running, will stop if the off/
reset position is selected. If the compressor during
normal running has afault causedby eitheroverload
or high discharge temperature, the compressor will
stop. After a fault has been cleared, the compressor
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