CLS200 Series User’s Guide
Chapter 3: Using CLS200
60
What Happens if a Failed Sensor Alarm Occurs?
If a failed sensor alarm occurs:
• The controller switches to manual mode at the output power set with the SENSOR FAIL HT
OUTPUT and SENSOR FAIL CL OUTPUT parameters in the SETUP LOOP OUTPUTS menu.
(The output power may be different for a thermocouple open alarm. See Thermocouple Open
Alarm on page 60.)
• The controller displays an alarm code and alarm message on the display. See Alarm Displays
on page 53.
• The global alarm output is activated.
Thermocouple Open Alarm
The thermocouple open alarm occurs if the controller detects a break in a thermocouple or its leads.
If a thermocouple open alarm occurs, the controller switches to manual mode. The output level is
determined as follows:
• If the HEAT/COOL T/C BRK OUT parameter in the SETUP LOOP OUTPUTS menu is set to
ON, then the controller sets the output power to an average of the recent output.
• If the HEAT/COOL T/C BRK OUT AVG parameter is set to OFF, then the controller sets the
output to the level set with the SENSOR FAIL HT/CL OUTPUT parameter in the SETUP
LOOP OUTPUTS menu.
Thermocouple Reversed Alarm
The thermocouple reversed alarm occurs if the temperature goes in the opposite direction and to
the opposite side of ambient temperature than expected—for example, a loop is heating and the
measured temperature drops below the ambient temperature.
The thermocouple reversed alarm is disabled by default. To enable this alarm, set the REVERSED
T/C DETECT parameter in the SETUP LOOP INPUTS menu to ON. It may be disabled if false
alarms occur in your application.
Thermocouple Short Alarm
The thermocouple short alarm occurs if the process power is on and the temperature does not rise
or fall as expected. To enable the thermocouple short alarm, you must do the following:
• Choose a digital input for the PROCESS POWER DIGIN parameter in the SETUP GLOBAL
PARAMETERS menu.
• Connect the digital input to a device that connects the input to controller common when the
process power is on.
RTD Open or RTD Shorted Alarm
The RTD open alarm occurs if the controller detects that the positive or negative RTD lead is broken
or disconnected.
The RTD shorted alarm occurs if the controller detects that the positive and negative RTD leads
are shorted.
You do not have to set any parameters for the RTD alarms.
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