Watlow CLS200 - Manual (Page 81)

CLS200 Series User’s Guide Chapter 3: Using the CLS200
Doc.# 0600-3050-2000 Watlow Anafaze 65
Failed Sensor Alarms
Failed sensor alarms alert you if one of the following condi-
tions occurs:
• Thermocouple open
• Thermocouple shorted (must be enabled)
• Thermocouple reversed (must be enabled)
• RTD open positive input or open negative input
• RTD short between the positive and negative inputs
What Happens if a Failed Sensor Alarm Occurs?
If a failed sensor alarm occurs:
• The controller switches to manual mode at the output
power indicated by the SENSOR FAIL HT OUTPUT and
SENSOR FAIL CL OUTPUT parameters in the SETUP
LOOP OUTPUTS menu. (The output power may be dif-
ferent for a thermocouple open alarm; see Thermocou-
ple Open Alarm on page 65.)
• The controller displays an alarm code and alarm mes-
sage on the display. See Alarm Displays on page 58.
• The global alarm output is activated.
Thermocouple Open Alarm
The thermocouple open alarm occurs if the controller de-
tects a break in a thermocouple or its leads.
If a thermocouple open alarm occurs, the controller switch-
es to manual mode. The output level is determined as fol-
lows:
• If the HEAT/COOL T/C BRK OUT parameter in the
SETUP LOOP OUTPUTS menu is set to ON, then the con-
troller sets the output power to an average of the re-
cent output.
• If the HEAT/COOL T/C BRK OUT AVG parameter is set
to OFF, then the controller sets the output to the level
indicated by the SENSOR FAIL HT/CL OUTPUT pa-
rameter in the SETUP LOOP OUTPUTS menu.
Thermocouple Reversed Alarm
The thermocouple reversed alarm occurs if the tempera-
ture 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 param-
eter in the SETUP LOOP INPUTS menu to
ON. It may be dis-
abled if false alarms occur in your application.