Instruction manual

IMP I IMP/P I SAM Hot Runner Controllers Instruction Manual
8
switched to manual mode. The output power will be a
function of the manual control knob setting. Since the
controller is now operating in open-loop mode, extreme
care must be taken when adjusting to prevent excess
output power that would overheat the load.
4. No heat:
The IMP series controller has included in its micro-
processor a program that detects that the temperature is
not rising as it should in response to full power output. “No
heat” is defined as the condition under which the tempera-
ture does not increase more than 2 ºF during a 60-second
interval during start-up. It takes 60 seconds to detect “No
heat” when power is first turned on in closed-loop mode.
If CompuStep is active, the test is not performed until after
CompuStep is finished (5 minutes). When “No heat” alarm
is detected, output power is cut off.
What to do:
a. Try resetting the controller by turning its AC power
OFF and then ON.
b. If “No Heat” persists, then the problem could be one
of the following.
1) Open heater or load.
2) Thermocouple shorted. Switch to manual mode
to override this condition.
3) Load circuit open. This can be caused by an open
power cable, an open connector or a failed triac in
the controller. Exchange the module with a known
good module to eliminate suspect triac or module.
4) Slow heater. Use higher power heater or operate
in manual mode until setpoint is achieved.
5) Thermocouple too far away from heat source that
causes less than 2 ºF (1 ºC) rise in 60 seconds
due to thermal lag. Move thermocouple as close
to heater as possible or use heater with built in
thermocouple.
6) To defeat “No Heat” circuit, if not used or required,
remove jumper J4 and that circuit will no longer
be active.