Watlow PM PLUS 6 - Page 113

Watlow PM PLUS™ 6 • 113 • Chapter 10 Appendix
Indication Issue Issue / Possible Cause(s) Corrective Action
Ambient Error Sensor does not provide
a valid signal to controller
• Ambient error - cold junction
circuitry not working
• Return to factory for repair
Limit won’t clear
or reset
Limit will not clear or re-
set with keypad or digital
input
• Sensor input is out of limit set
point range
• Limit set point is incorrect
• Digital input function is incorrect
• Correct cause of sensor input out
of limit range
• Set limit set point to correct trip
point
• Set digital input function and
source instance
Limit Error Limit state cannot be
determined due to lack
of sensor input, limit will
trip
• Sensor improperly wired or open
• Incorrect setting of sensor type
• Calibration corrupt
• Correct wiring or replace sensor
• Match setting to sensor used
• Check calibration of controller
Limit Low Sensor input below low
limit set point
• Temperature is less than limit set
point
• Limit outputs latch and require
reset
• Incorrect alarm set point
• Check cause of under temperature
• Clear limit
• Establish correct limit set point
Limit High Sensor input above high
limit set point
• Temperature is greater than limit
set point
• Limit outputs latch and require
reset
• Incorrect alarm set point
• Check cause of over temperature
• Clear limit
• Establish correct limit set point
Loop Open Error
[1,2]
Open Loop Detect is
active and the process
value did not deviate by
a user-selected value in a
user specified period with
PID power at 100%.
• Setting of Open Loop Detect Time
incorrect
• Setting of Open Loop Detect
Deviation incorrect
• Thermal loop is open
• Open Loop Detect function not
required but activated
• Set correct Open Loop Detect Time
for application
• Set correct Open Loop Deviation
value for application
• Determine cause of open thermal
loop: misplaced sensors, load
failure, loss of power to load, etc.
• Deactivate Open Loop Detect
feature
Loop Reversed
Error [1,2]
Open Loop Detect is
active and the process
value is headed in the
wrong direction when the
output is activated based
on deviation value and
user-selected value.
• Setting of Open Loop Detect Time
incorrect
• Setting of Open Loop Detect
Deviation incorrect
• Output programmed for incorrect
function
• Thermocouple sensor wired in
reverse polarity
• Set correct Open Loop Detect Time
for application
• Set correct Open Loop Deviation
value for application
• Set output function correctly
• Wire thermocouple correctly, (red
wire is negative)
Ramping [1,2] Controller is ramping to
new set point
• Ramping feature is activated • Disable ramping feature if not
required
Autotuning [1,2] Controller is autotuning
the control loop
• User started the autotune function
• Digital input is set to start
autotune
• Wait until autotune completes or
disable autotune feature
• Set digital input to function other
than autotune, if desired