Chromalox 2104 Technical Manual 55
Probable Cause Control Output Response Display
Loss of process flow Turns control output off
In a control application where the process is being heated at one point and measured at a
point downstream, CLP Alarm could be used to detect a flow failure. If the process flow is
interrupted and heat is no longer transferred to the sensor, the controller output will
increase to 100%, the Loop alarm will start timing the load response and when the preset
Loop Timer value is reached, the Loop Alarm will be activated and the control output will
be turned off. The failure will be indicated by the lower display flashing LOOP. Loop Alarm
Output (Output #3, #4 or #5) will be activated if selected.
Probable Cause Control Output Response Display
Load Power is interrupted Turns control output off
(blown fuse or tripped circuit
breaker)
If load power is interrupted by the circuit protection devices (user supplied fuse or circuit
breaker), the Loop Alarm will be activated when the process variable goes outside of the
proportional band for a time greater than the preset Loop Timer value. The control output
will be turned off and the failure will be indicated by the lower display flashing LOOP. Loop
Alarm Output (Output #3, #4, or #5) will be activated If selected.
Probable Cause Control Output Response Display
Load fails (open circuit) Turns control output off
If the load fails open, the Loop Alarm will be activated when the process variable goes
outside of the proportional band for a time greater than the preset Loop Timer value. The
control output will be turned off and the failure will be indicated by the lower display
flashing LOOP. Loop Alarm Output (Output #3, #4, or #5) will be activated if selected.
Probable Cause Control Output Response Display
Load fails (short circuit) Turns control output Off
If the load fails shorted, power to the load will be interrupted by the circuit protection
devices (user supplied fuse or circuit breaker). The Loop Alarm will be activated when the
process variable goes outside of the proportional band for a time greater than the preset
Loop Timer value. The control output will be turned off and the failure will be indicated by
the lower display flashing LOOP. Loop Alarm Output (Output #3, #4, or #5) will be
activated if selected.
CLP Loop Alarm Conditions
The following table details conditions that activate a loop alarm, and gives
the controller response to the condition.
Figure 6.1 CLP Loop Alarm Conditions
LL
LL
L
OOPOOP
OOPOOP
OOP
88888888
88888888
8888
Flashing
LL
LL
L
OOPOOP
OOPOOP
OOP
88888888
88888888
8888
Flashing
LL
LL
L
OOPOOP
OOPOOP
OOP
88888888
88888888
8888
Flashing
LL
LL
L
OOPOOP
OOPOOP
OOP
88888888
88888888
8888
Flashing
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