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9
7.6 CONTROLS
Ingersoll Rand
Refrigerated Compressed Air Dryers are
equipped with the Microprocessor Control. This advanced
microprocessor-based controller has been engineered by
Ingersoll Rand
exclusively for use with
Ingersoll Rand
Compressed Air Dryers.
The Microprocessor Control cycles the refrigeration system
based on the dryer’s Chiller Temperature. A temperature
sensor samples the thermal mass temperature as it enters
the chiller exchanger. The Chiller Temperature Set point is a
user adjustable set point that is used to set the Refrigeration
Compressor Off temperature. Once the Chiller Temperature
has fallen below the Chiller Temperature Set point, the
refrigeration compressor will de-energize. The Operating
Temperature Differential is factory set at 4°F above the
Chiller Temperature Set point. Therefore, if a user adjusts the
Chiller Temperature at 36°F, the Refrigeration Compressor On
temperature will be 40°F.
In addition to the operation of the Nirvana™ Cycling dryers
as described above, the Microprocessor Control permits
monitoring of dryer parameters and enunciation of alarm
conditions.
The list below summarize the features the Microprocessor
Control:
2 X 16 Character Backlit LCD Display - Easy-to-
read display provides continuous indication of
dryer default parameter. Standard backlight
permits viewing of critical information in low light
environments.
Remote Start / Stop: Microprocessor Control-
equipped dryers offer a unique remote start / stop
feature. This feature allows the dryer to be operated
via a remote user-supplied switch.
Remote Alarm Contact: Microprocessor Control-
equipped dryers include a remote alarm contact
to provide indication of any of the dryers alarms
described later in this manual. Contact rated for
2A / 120V max.
The Microprocessor Control features three levels of access.
The default level CUSTOMER MODE permits adjustment of
dryer parameters to address seasonal variations for drain
timing and pressure dew point temperature. A protected
TECHNICIAN MODE permits access to and manipulation
of additional parameters. A password protected FACTORY
MODE is also included for use with
Ingersoll Rand
Service
Personnel for troubleshooting the dryer.
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The Microprocessor Control includes a digital readout for
monitoring the discharge pressure of the refrigerant gas
exiting the compressor. This reading will vary dependent
upon condenser type as indicated below:
For air-cooled applications, condensing fans are
cycled on and off by the Microprocessor based on
the refrigerant discharge pressure. The primary fan
is cycled on at 275 psig and off at 195 psig. Should
the discharge pressure continue to climb above 335
psig, the secondary condensing fan will cycle on. As
discharge pressure is reduced below 235 psig, the
secondary fan will cycle off.
Water cooled condensers utilize a water regulating
valve (Note Figure 2). The water regulating valve
comes pre-adjusted from the factory at 250 psig
discharge pressure. To compensate for water
temperature variation, it may be necessary to adjust
the water regulating valve to maintain a 250 psig
discharge pressure. Adjustment can be done by
rotating the adjusting screw counterclockwise for an
increase in discharge pressure. For conditions where
low water temperature and/or high water pressure
are expected it is advisable to install a water pressure
regulator ahead of the condenser.
ADJUSTMENT
SCREW
WATER REGULATING VALVE
FIgURE 2
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7.0 PRINCIPLES OF OPERATION
120.26A D4290NCHPW400F Installation Operation and Maintenance Manual
