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Operation with Advanced Microprocessor Controls
9
Select Control Type
• Intelligent (Chilled Water only)
• Proportional (all unit types)
• Tunable PID (Chilled Water or SCR Reheats only)
The type of system control method used by the microprocessor can be selected from the front panel.
The default setting is Intelligent, which approximates the actions that a human operator would take
to maintain precise, stable control. The control logic uses Artificial Intelligence techniques including
“fuzzy logic” and “expert systems” methods to maintain precise, stable control and increase reliability
by reducing component cycles. Proportional is a standard control method that uses one gain factor
(temperature sensitivity adjustment). Tunable PID (Proportional, Integral, and Derivative) uses
three gain factors selected by the operator. PID allows precision tuning, but requires an experienced
operator and seasonal adjustments. Note that if PID is selected, it is used for temperature control
while humidity will continue to use Proportional control. Refer to 4.0 - System Performance with
Advanced Microprocessor Controls for more detail on types of controls.
Setup Alarms
Selecting SETUP ALARMS will step to the following menu:
•SET TIME DELAYS
• ENABLE ALARMS
• ENABLE COMMON ALARM
• SET CUSTOM ALARMS
Each individual alarm can be programmed with a time delay from 0 to 255 seconds. Each individual
alarm can be ENABLED or DISABLED and each individual alarm can be programmed to energize or
not to energize the Common Alarm Relay.
Set Time Delays—By programming a time delay for an alarm, the system will delay the specified
amount of time before recognizing the alarm. The alarm condition must be present for the amount of
time programmed for that alarm before it will be annunciated. If the alarm condition goes away
before the time delay has timed out, the alarm will not be recognized and the time delay timer will be
reset. For software alarms such as Loss of Power, Short Cycle, and Low Suction Pressure, a time
delay will only delay the annunciation of that alarm. The condition of the alarm is not applicable
because the condition has already occurred. For these alarms the time delay should be left at the fac-
tory default of 0. Table 5, below, shows the default time delays for each alarm.
Table 5 Alarm default time delays
Alarm
Default Time
Delay (seconds)
Humidifier Problem 2
High Head Pressure 2
Change Filter 2
Loss of Air flow 3
Custom Alarm #1 0
Custom Alarm #2 0
Custom Alarm #3 0
Custom Alarm #4 6
High Temperature 30
Low Temperature 30
High Humidity 30
Low Humidity 30
Low Suction Pressure 0
Short Cycle 0
Compressor Overload 2
Main Fan Overload 5
Loss of Power 0