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26 . EMERGENCY STOP
This button when depressed will stop the
compressor immediately and display an emergency
stop alarm message.
27 . POWER L .E .D .
This will illuminate when the 8V controller supply is
available.
28 . AUTOMATIC RESTART L .E .D .
This will illuminate when the machine has shutdown
due to low air demand. The compressor will restart
and load automatically as soon as the demand for air
resumes.
DISPLAY MESSAGES
When the compressor is running normally, the
display will indicate the package discharge pressure
and illuminate the corresponding L.E.D. [1]. An
arrow will also appear in the far right of the display
indicating pressure band selection. Pressing display
select [19] will change the display value and the
corresponding L.E.D. will illuminate. The controller
monitors all aspects of the compressor while running
and will display warnings or in severe conditions
execute an emergency stop and display alarm
conditions.
MACHINE CONTROL MODES
CAPACITY CONTROL
The compressor is designed to work with two types of
capacity control, to suit the individual plant requirements.
These controls are:–
A. On line – Off line. (Fitted as standard)
B. On line – Off line, with Upper Range Modulation.
(Optional extra)
Either is available by selection at the control panel.
ON LINE – OFF LINE CONTROL
For applications that require a widely varying air demand,
this mode of control will deliver air at full capacity or zero
capacity with low receiver pressure.
This mode of operation is controlled by the pressure
transducer responding to changes in plant air pressure.
This sensor energizes the load solenoid valve which in
turn operates the venting valve (blowdown) and the
closing of the atmospheric vent opening in the air inlet
valve.
The compressor then delivers full capacity air to the plant
system. If the air pressure in this system rises to the upper
set point of the pressure setting, the load solenoid valve
is de–energized allowing the inlet valve to close. At the
same time, the venting valve opens allowing the receiver
pressure to drop.
The pressure setting has a range of 12 psi (0.83 bar)
between its upper and lower set points.The upper set
point is set at 3 psi (0.2 bar) above the compressor rated
discharge pressure.
8044766 Rev.A
INTELLISYS® OPTION
UPPER RANGE MODULATION CONTROL (Optional
Extra)
For plants having a relatively high and constant air
demand, Upper Range Modulation is the recommended
mode of control.
Upper range modulation retains the features of On line
– Off line control but provides the throttling of the inlet
air flow as the line pressure rises to the upper set point of
the off–line pressure setting.
By bleeding off a small amount from the regulator valve,
which energises the Modulate Solenoid Valve, a reduction
in the air signal to the pneumatic cylinder on the inlet
valve allows the cylinder to 'trim' the inlet valve position
as dictated by changing line pressure. Modulation begins
when the compressor reaches about 94% of the rated
line pressure and is factory set to modulate down to
approximately 70% of rated capacity.
If the air demand decreases to a level below the 70%
modulated output, the line pressure will increase slightly
to the upper limit of the pressure setting, when the
compressor then changes to the Off line control position
and operates with the receiver vented.
AUTOMATIC START/STOP
For plants that have a widely varying plant air demand,
larger air storage capacity, and/or want automatically
available stand–by air capacity, Automatic Start–Stop
Control Option is available.
During periods of low demand, if the line pressure rises to
the off line air pressure set point of the lntellisys® , a timer
is energized and begins to time out. The automatic restart
time is adjustable in a 2–60 minute range. The timer will
continue to operate as long as the plant line pressure
remains above the on line set point of the Intellisys® . If
the timer continues to operate for as long as its adjusted
time setting, a contact in the lntellisys opens to de–
energize the compressor starter coils. At the same time,
a yellow Automatic Restart light on the lntellisys® panel
is lit and the message AUTO RESTART will be displayed to
indicate the compressor has shut down automatically and
will restart automatically.
The automatic restart will take place when the line
pressure drops to the online set point of the Intellisys®.
To operate in the automatic start/stop mode, proceed
with the following steps:
1. Press the SET button until the message AUTO S/S
OFF is displayed.
2. Push the up or down arrows to select the auto
start/stop function (ON or OFF). AUTO S/S OFF in the
display indicates auto start/stop is disabled (OFF).
AUTO S/S ON in the display indicates auto start/
stop is enabled (ON). Press the SET button to store
function. The display will flash to acknowledge and
then display AUTO S/S 10 MIN.
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