818P runs at 100% power

I was running a standard program I've run many times before and had the furnace breaker trip? It appears to be an issue with my 818P controller. If I run a program with the HL set at 37% and start the program the OP shows 37% and does not change even when the temp setpoint is exceeded. The temp continues to climb well past the setpoint and the OP stays pegged at 37%.

If I change over to manual mode and run the OP at 5% I get a corresponding volt/amp reading that's very linear as I ramp up the OP. From 5% to 30% in 5% increments it preforms as expected.

Could I have inadvertently changed something in the program?? Or should I suspect the controller's gone bad? I'm in the process of installing a backup 818P to see if I get the same results. Any ideas would be appreciated.
1 person has
this problem
+1
Reply
  • My 818P test with the backup isn't going to work. I believe the output is different.

    Part #'s are 818P/TC/R0V5 vs 818P/TC/RLGC

    Do you know what the output are
    R0V5 = _____________ and
    RLGC = _____________ ?
  • (some HTML allowed)
    How does this make you feel?
    Add Image
    I'm

    e.g. kidding, amused, unsure, silly happy, confident, thankful, excited sad, anxious, confused, frustrated indifferent, undecided, unconcerned

  • Jon (Official Rep) February 08, 2017 21:13
    Hello Bob,
    I'm not sure which is your original unit but the R0V5 is 0 to 5volt analogue output so if the OP shows 50% the O/P should be 2.5V, 75%=3.75v....& so on. If this is the faulty unit I suspect that the capacitors have dried out on the o/p board!

    RLGC is a Logic O/P which is either on/off (0 to 18v approx.) so if your Heat cycle time(Hc) was 5seconds and you were at 50% O/P the logic would be on for 2.5secs & off 2.5secs.

    Regards, Jon
  • (some HTML allowed)
    How does this make you feel?
    Add Image
    I'm

    e.g. kidding, amused, unsure, silly happy, confident, thankful, excited sad, anxious, confused, frustrated indifferent, undecided, unconcerned

  • Thanks Jon,
    The R0V5 is my original controller. I just remembered I couldn't mix the 818P's because of the different outputs. Thanks for the explanations.

    I'm going to check my PID's (TI, TD and PB) and if they look ok run one more test not using manual mode or the program, just raise the setpoint to say, 150 C ,and then see if it stops by itself or not.
  • (some HTML allowed)
    How does this make you feel?
    Add Image
    I'm

    e.g. kidding, amused, unsure, silly happy, confident, thankful, excited sad, anxious, confused, frustrated indifferent, undecided, unconcerned

  • Jon,
    I'm thinking it's not the 818P. Settings were as follows:
    Pb was 7.5, now 10

    Ti was 30, now 300 (I think I inadvertently set at 30.0 thinking it was 300) I had a tec in last summer to help me diagnose an SCR problem and he ran a self tune with the oven off and it screwed up the PID's so I reset.

    Td was 50, now at 60.

    Test run by raising the SP to 100 C worked just fine. OP started at about 30% and dropped off to about 5% at 100 C, overshot by 5 degrees and slowly came back down.
    So, I'm thinking I have a heating element that's slowly degraded to the point it's causing problems that only show at higher temps 1,000 C or more. Typical runs for me are 1550 to 1800. Any thoughts, do you think that makes sense?
  • (some HTML allowed)
    How does this make you feel?
    Add Image
    I'm

    e.g. kidding, amused, unsure, silly happy, confident, thankful, excited sad, anxious, confused, frustrated indifferent, undecided, unconcerned

  • Jon (Official Rep) February 09, 2017 23:25
    Hi Bob,
    This does make sense, but I would be mindful of the 818's age as I mentioned above the capacitors can dry out, causing slow or erratic voltage o/p - I would just see how it performs over the next week or so.
    Jon
  • (some HTML allowed)
    How does this make you feel?
    Add Image
    I'm

    e.g. kidding, amused, unsure, silly happy, confident, thankful, excited sad, anxious, confused, frustrated indifferent, undecided, unconcerned

  • Actually since you brought up the subject I have been talking about a direct replacement (if possible). I'd like one that interfaces with a laptop so the programming is easier and will allow data logging. When I do have this kind of problem it would be nice to know exactly where I was at and what some of my reading were.

    Also would like to monitor over an IP connection to a mobile device so I don't have to be there so much when I'm doing some of the longer runs. A very normal run for me is one that's 45 hours long.

    More ramps would also be helpful, even two because I have to use one to fool the controller so it will shut off.
  • (some HTML allowed)
    How does this make you feel?
    Add Image
    I'm

    e.g. kidding, amused, unsure, silly happy, confident, thankful, excited sad, anxious, confused, frustrated indifferent, undecided, unconcerned