CLS200 Series User’s Guide
Chapter 8: Troubleshooting and Reconfiguring
141
In a heating application, a high process alarm setpoint or high deviation alarm may indicate one of
the following:
• The setpoint and high process alarm setpoint have been lowered and the system has not had
time to cool to within the new alarm limit.
• The control status is set to manual and the heat output is greater than 0%.
• The load has decreased such that the temperature has risen.
• The heater is full-on due to a hardware failure.
• The system is so poorly tuned that the temperature is cycling about setpoint by more than the
alarm setpoint limit.
Resetting a Process or Deviation Alarm
Your response to an alarm depends upon the alarm type setting, as explained in
Table 8.2
below.
Table 8.2
—
Operator Response to Alarms
ALARM TYPE
OPERATOR RESPONSE
Control
The operator does not need to do anything. The alarm clears
automatically when the process variable returns within the alarm
setpoint.
Alarm
Acknowledge the alarm by pressing
ALARM ACK
on the controller or
by using software. The alarm clears after the process variable returns
within the alarm setpoints and the operator has acknowledged it.
Failed Sensor Alarms
When a failed sensor alarm occurs, the controller switches to the single loop display for the loop with
the alarm and displays an alarm code on the screen.
Table 8.3
—
Failed Sensor Alarm Codes
CODE
ALARM
DESCRIPTION
FS
Failed Sensor
Open thermocouple.
RT
Reversed
Thermocouple
Termperature changed in the opposite direction than expected.
ST
Shorted
Thermocouple
Temperature failed to change as expected.
RO
RTD Open
Positive or negative lead is broken or disconnected.
RS
RTD Shorted
Positive and negative leads are shorted.
A failed sensor alarm clears once it has been acknowledged and the sensor is repaired.
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