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CN 2110
Omega
Control Operation
The CN 2110 is shipped from the factory with PI (proportional/integral)
control. Proportional control actually determines the percent of heat
needed to control the process. The factory setting for the Proportional
Band is 25°F and the Automatic Reset (Integral) is set at 0.1 repeats/
minute. These settings will control many processes without any changes
to the controller.
If the process is unstable or too sluggish, the Proportional
Band and Automatic Reset can be changed in the menu configuration.
Tuning PI Control
Adjust Proportional Band
The objective of the proportional band adjust-
ment is to find the proportional band setting at which the process tempera-
ture stabilizes and does not oscillate. If the temperature display is oscillat-
ing, increase the Proportional Band (doubling the value) until the tempera-
ture display has stopped oscillating. To establish a quick response to control
upsets, adjust for the smallest band that provides stable control (does not
oscillate). Note: The temperature at this point may not be at set point, but
will be stable.
Adjust Automatic Reset (Integral) The Automatic Reset (Integral)
automatically removes the offset between process temperature and set
point. If the process is too sluggish in approaching set point, double the
automatic reset. Too much automatic reset will make a process unstable.
Cycle Time
Cycle time setting determines how often to switch the output
to the heater. For example, if the cycle time is 1 second and the CN 2110
needs a 75% output, the output will be on for 3/4 of a second and off 1/4
of a second. Units with relay control outputs (R1 or R20) are shipped with
a 30-second cycle time. Units with solid state relays or solid state relay
drives (T1, T5, T10, or DC) are shipped with a 1-second cycle time.
Section 5—Control and Alarm Operation
Alarm Operation
(optional)
16
Section 5–Control and Alarm Operation
An alarm relay output is optional on the CN 2110. An alarm can help
protect the process when a too high or too low temperature occurs.
High Alarm:
This alarm is a high absolute alarm that actuates when the
process temperature is equal to or greater than the alarm set point. For
example, if the high alarm set point is 500°F, the alarm will always actuate
when the process temperature reaches 500°F.
Low Alarm:
The low absolute alarm actuates when the process temperature
is equal to or less than the alarm set point. The low alarm features a power-
up inhibit to prevent undesirable alarms during process start up. After the
unit reaches control set point, the low alarm will respond.
Alarm Dead Band:
The alarm relay de-energizes (resets) when the tem-
perature crosses out of the alarm dead band. For example, if the high alarm
is set to 500°F and the alarm dead band is 5°F, the alarm condition will not
reset until the process temperature reaches 495°F.
To enable the alarm relay, select either high or low alarm type and set the
alarm set point. An alarm condition is indicated when the Alarm light to
the left of the display illuminates. Alarm type, set point, and dead band are
selectable through the user configuration interface.