Control System, Functional Description - Sullair ES--6 Series Operator's Manual And Parts List

Figure 2- -2 Encapsulated Compressor System
2.6 CONTROL SYSTEM, FUNCTIONAL DE-
SCRIPTION
The purpose of the compressor control system is to
maintain compressor capacity to meet the system
demand.
It consists of an inlet valve, solenoid valve, con-
trol lines and the motor start selector switch.
The selector switch has three settings: MANUAL/
START, OFF/RESET and AUTOMATIC START/
STOP.
MANUAL MODE
The compressor motor will start and the air control
solenoid valve will be energized. The compressor
will start to deliver compressed air. When no air is
being used, the service line pressure rises to the
setting (cut--out pressure) of the pressure switch.
The system pressure switch opens, interrupting the
electrical power to the solenoid valve. The solenoid
valve allows control air to the inlet valve, unloading
the compressor and the motor continues to run.
When the line pressure drops to the low setting of
DESCRIPTION
the pressure switch, the pressure switch closes, re--
energizing the normally open solenoid valve and al-
lowing the compressor to load again.
OFF/RESET MODE
The compressor motor, if running, will stop if the off/
reset position is selected. If the compressor during
normal running has a fault caused by either overload
or high discharge temperature, the compressor will
stop. After a fault has been cleared, the compressor
can not be restarted unless the Off/Reset mode is
selected on the selector switch, prior to starting in
any other mode of operation.
AUTOMATIC MODE
In the automatic mode of operation, the air system
pressure switch opens, interrupting the electrical
power to the air control solenoid valve; the compres-
sor unloads and the motor will stop. The motor will
automatically restart when the compressor sump
pressure drops to the minimum setpoint on the
sump pressure switch and the line pressure drops
below the setpoint of the air pressure switch.
Section 2
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