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What's behind these grouphead bolts??

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  • #16
    What's behind these grouphead bolts??

    If this machine is quite old then I am thinking that the problem could be back EMF. It's common practice in DC circuits to use some diodes on the solenoid coil to counter this problem.

    It makes some sense ( to me only perhaps) when the group is switched off the solenoid coil creates back EMF while the magnetic field collapses, which may be enough to trip the RCD. If you think it's plausible then an oscilloscope could tell you.

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    • #17
      Thanks for the info.

      The machine has been running fine for three days with a replaced solenoid coil so it looks like that's the culprit. In saying that there was a small amount of earth leakage from the element but apparently well with in the threshold for a trip. We have isolated that part of the element to be sure, so now its 2kw instead of 3kw and as it won't be a high volume cafe machine we think we will be OK.

      It has had a few people scratching their heads as it seemed to be intermittent and mostly when the switch was flicked off, but then it wouldn't always allow us to turn the machine on straight away, when the switch tripped the breaker, without tripping again, it was like the fault was still there, so maybe it has been a combination of faults that are hopefully now taken care off.

      Next challenge is getting used to the power of the steam.

      Thanks for all the input

      G

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