Control System, Functional Description; Instrumentation, Functional Description - Sullair ES-6 Series User Manual

SECTION 2
2.6 CONTROL SYSTEM,
FUNCTIONAL DESCRIPTION
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 motor start
selector switch.
The selector switch has three settings: MANUAL/
START, OFF/RESET and AUTOMATIC START/
STOP.
M M
ANUAL ODE
In the manual mode the ball valve should be closed
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 compressor
will start to deliver compressed air. When the air
demand is less than the rated flow for the
compressor, the service line pressure will rise to the
pressure switch cut-out setting. The system pressure
switch opens, interrupting the electrical power to the
solenoid valve. The solenoid valve opens allowing
pressure to be applied to the inlet valve causing the
inlet valve to fully close. The compressor will
continue to run (unloaded) until the line pressure
drops to the low setting of the pressure switch--the
pressure switch closes, reenergizing the normally
open solenoid valve and allows the compressor to
load again.
M M C
ANUAL ODULATION ONTROL
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 of the
pressure regulator. The pressure regulator will them
begin to open allowing pressure to be applied to the
inlet valve. The pressure regulator will modulate the
inlet valve to match system demand.
M
ODE
O /R M
FF ESET ODE
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 starting in any
other mode of operation.
A M
UTOMATIC ODE
In the automatic mode of operation, the compressor
operates the same as in the manual mode except
that when the pressure switch unloads the machine
the compressor motor will stop. The motor will
automatically restart when the line pressure drops to
below the set-point of the air pressure switch. If the
compressor is equipped with a wye-delta starter, the
compressor will not restart until the compressor
sump pressure drops to the minimum set-point on
the sump pressure switch. It is not recommended to
open the pressure regulator ball valve for the
automatic mode of operation.
2.7 INSTRUMENTATION,
FUNCTIONAL DESCRIPTION
Due to the simplicity of the ES-6 Series compressor,
the only instrumentation necessary is a line pressure
gauge which is located on the left side of the
electrical control center and a discharge temperature
gauge which is located on the right side of the
electrical control center. The line pressure gauge
reads plant air system pressure only.
NOTE
At compressor shutdown, the sump pres-
sure is released to atmosphere through
the solenoid valve. The line pressure
gauge will continue to read system pres-
sure.
ES-6 USER MANUAL
17