Despatch Protocol Controller - Manual (Page 45)

39
Troubleshooting
PROBLEM/
SYMPTOM
PROBABLE
CAUSE
SUGGESTED CORRECTIVE ACTION
Erratic
temperature
control The controller typically has a proportion band ( PB ) of 5°F.
• If the heater is not cycling ON when the process
displayed temperature is 3°F or more below the
setpoint temperature, check:
• Defective Controller (will not gate SSR)
• Open Heater Fuses
• Tripped Hi-limit controller
• Open Hi-limit relay
• If the heater is not cycling OFF when the process
displayed temperature is 3°F or more above the
setpoint temperature, check:
•
Defective Controller (Temperature runaway)
• Shorted SSR
• Tuning parameters are incorrect (ex. CZO value
too large)
Temperature will
not reach the
Setpoint The heater is not
turning ON
Defective SSR
The Hi-limit relay
does not click or
pull in when
pressing the
HEATER ON
pushbutton
• Defective Controller (will not gate SSR)
• Open Heater Fuses
• Tripped Hi-limit controller
• Test SSR gate signal output.
• Check both the incoming and output wiring and
voltage.
• Check for loose wiring connector. Replace Protocol.
Display reads
“HL ERROR”
(blinking) The process
temperature has
exceeded the Hi-
limit temperature
setpoint.
Controller
Calibration
Set the hi-limit to a higher temperature and press the
RESET pushbutton.
Check DIAGNOSTICS MODE for actual temperature readout
of the Hi-limit (HL-T/C). If the reading is off by greater
than 2-3 degrees or displays 500°C (932°F), calibrate the
controller.
Display reads
“S-TC ERR”
(blinking) The Control
thermocouple is
open • Check for loose connections on the Control T/C
terminals (SEN).
• Defective T/C. Remove the T/C and short the
terminals with a jumper. The control should display
ambient temperature.
Display reads
“H-TC ERR
(blinking) The Hi-limit
thermocouple is
open • Check for loose connections on the Hi-limit T/C
terminals (HIL)
• Defective T/C. Remove the T/C and short the
terminals with a jumper. The control should display
ambient temperature