QRI Relay Problem

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts
  • smoothquark
    Automated Home Sr Member
    • Oct 2009
    • 69

    QRI Relay Problem

    Hi! Have s strange issue - one of the relays in one of my QRI modules seems to have got "stuck". It remains on regardless of what I do - Cortex thinks the light is off, but in actual fact it is on. Tried in sequence: reset the QRI (red button), turn off power to the idratek modules, stop and start network and exit and restart Cortex all to no avail. Is it possible for the relay to have physically got "stuck"? Is there anything else I can do?
  • chris_j_hunter
    Automated Home Legend
    • Dec 2007
    • 1713

    #2
    we're finding this, too ... now & then, on some Lights ...

    we find, in the Lights Behaviour window, that clicking On & Off, in the heuristic area, once twice or sometimes three times always sorts it ...

    first times it happened, we thought the relay had maybe seized, perhaps because we're using CFLs, but we find it happens on an LED Light, too, and it's always recoverable, as above ...

    haven't been able to correlate it with anything, but it happens on some Lights more often than others ...

    QRIs & DRBs, in our case, so maybe not module-type specific ...
    Last edited by chris_j_hunter; 26 August 2013, 12:40 AM.
    Our self-build - going further with HA...

    Comment

    • smoothquark
      Automated Home Sr Member
      • Oct 2009
      • 69

      #3
      Tried that as well - did not work. Funnily enough, when the power to the QRI is turned off and turned on, it sounds like the relay clicks, so the relay probably has not got physically "stuck". Not sure what is going on!

      Comment

      • chris_j_hunter
        Automated Home Legend
        • Dec 2007
        • 1713

        #4
        >when the power to the QRI is turned off and turned on ...

        power meaning mains, presumably, and lights also go out & on again, or ... ?
        Last edited by chris_j_hunter; 26 August 2013, 09:39 AM.
        Our self-build - going further with HA...

        Comment

        • smoothquark
          Automated Home Sr Member
          • Oct 2009
          • 69

          #5
          Tried turning off the 12V supply to the QRI and unplugging the connector - light remains on.
          When the MCB is switched off, the light goes off but comes back on when the MCB is switched on, regardless of what state the QRI is in. I suspect the relay has to be stuck in the closed state - any ideas on how to get it unstuck? The lights are my kitchen downlights - 6x 50W (230V) LED. Trying repeated "toggle" in the Lights Behaviour.

          Comment

          • Karam
            Automated Home Legend
            • Mar 2005
            • 863

            #6
            The symptoms indicate that your relay contacts have become welded. This is further supported by your description of the lights as being LED types (though I think you might mean 50W equivalents rather than actually 50W each). Unfortunately the design of CFL and LED drivers in such lamps tends to have a fairly large capacitor facing the power and I don't think many if any manufacturers bother with any kind of current limiter. This means when you switch power to the lamp you can potentially have a very high current spike (imagine you happen to switch on at the peak of the mains cycle (~325V) into a fully discharged capacitor). If you have more lamps in parallel then you add up the capacitance and multiply the current peak by the number of lamps. Anyhow end result is that the relay contacts may see spikes reaching many 10's or possibly even 100s of amps. Doesn't last very long but enough to eventually cause a spot weld on the contacts.

            The QRH's are likely to be somewhat more resistant to this issue because the bigger relays have have a higher current capacity in general but also better choice of contact material is available for that relay format. Ultimately however I feel this might be just delaying the eventual problem and that it is better to deal with the cause if possible. One way is to fit current limiting devices at the QRI output. These can be obtained in the form of specialised thermistors which have a relatively high resistance cold but then this drops to some reasonable value as the thermistor warms up. So as you turn th elight on the current is limited by the thermistor resistance but then this quickly drops to allow normal operation. The tradeoff is size vs working temperature. In other words its important that under normal working conditions the thermistor doesn't get too hot. Since LED and CFL lamps need only relatively small amounts of current (that's the whole point of them) then this is a workable solution. I haven't got any particular devices to recommend off the top of my head but I'm sure I have done so in previous forum posts and elsewher so just have to dig it up and maybe need to put this somewhere more accessible these days with the obvious trend in lamp technology.

            Finally another approach we are working on is a zero-crossing switched Triac version of the QRI. This should be much better suited to these types of lamps and also should in principle have much longer lifespan due to no mechanical parts. Infact we already do have a variant of the XRM (known as the XTM) which uses these though still in trials.

            The problems that Chris is describing are probably due to a different root cause since I believe he has switched dimmable lights on the end of the relays with various bits of logic in between to prevent the dimming function from being actioned if for some reason the light is automatically turned on too quickly after being turned off, so a bit more complicated to dissect.

            Comment

            • smoothquark
              Automated Home Sr Member
              • Oct 2009
              • 69

              #7
              Thanks Karam - thought that might be the case. The lamps are 50W equivalents (x6). Have sent an email to discuss possible options. Just a thought - is it just LED replacements that are a potential problem or also the energy saving lamps? If the latter are going to cause problems I need to get my QRIs replaced.

              Comment

              • chris_j_hunter
                Automated Home Legend
                • Dec 2007
                • 1713

                #8
                in our small experience, energy-saving lamps are a mixed bunch - it's impossible to generalise about ESLs, or CFLs, or LEDs, even brands .. they vary so much, in all the essential parameters - colour, longevity, temperature-dependence, time-to-brightness, efficiency, price, etc, etc - so why not start-up current, too ... ??
                Our self-build - going further with HA...

                Comment

                • Karam
                  Automated Home Legend
                  • Mar 2005
                  • 863

                  #9
                  I think CFLs also have a similar problem and cause. I have also noticed a general trend where manufacturesrs simply say 'Energy saving lamp' but don't specify technology eg. is it a halogen, a CFL or LED. In particular the latter two can be difficult to tell apart these days since the size of CFLs has decreased and both can come in similar sized opal glass format. Whereas I personally would like to know which is being used (holding out for LED ...). I think in the short term inrush limiters or choosing QRHs over QRIs might be an approach. Or if you have XRMs then you can start requesting XTMs instead (note these are rated to 1A/channel so fine for low energy lighting and ac switching but not direct replacement for XRM in other circumstances)

                  Comment

                  • chris_j_hunter
                    Automated Home Legend
                    • Dec 2007
                    • 1713

                    #10
                    this takes a look inside a CFL :



                    and another look at inrush current :

                    Last edited by chris_j_hunter; 28 August 2013, 11:51 AM.
                    Our self-build - going further with HA...

                    Comment

                    • smoothquark
                      Automated Home Sr Member
                      • Oct 2009
                      • 69

                      #11
                      Been looking for current limiters - cannot really find any on this forum! Perhaps not looked hard enough? Anyway, is this (http://www.ebay.co.uk/itm/NTC-Inrush...item4611a14cf9) any good? Any other solutions? Perhaps some way of incorporating a daughter board with a thermistor and fuse where the fuse now plugs in? I presume has to be serial ? More components to get?

                      I do need to get my QRI sorted - family not happy being dependent on me to turn on and off the kitchen lights using the MCB! My friendly electrician is on holiday as well....

                      Comment

                      • chris_j_hunter
                        Automated Home Legend
                        • Dec 2007
                        • 1713

                        #12
                        not sure, but this may have been what Karam was thinking-of :



                        there are a few to choose from (neighbours on that 'site) ... so choose carefully !

                        we also bought some of these :



                        none used, yet, though, because it seems our CFLs are reasonably well behaved / controlled (finger's crossed) ...
                        Last edited by chris_j_hunter; 28 August 2013, 10:38 PM.
                        Our self-build - going further with HA...

                        Comment

                        • Karam
                          Automated Home Legend
                          • Mar 2005
                          • 863

                          #13
                          The first link is about transient suppressors and can be useful for dealing with issues due to noise spikes normally caused by switching off inductive loads for instance but also when switching on some types of devices such as fluorescents. In this case the device can be wired in parallel to relay contacts and device to use should be type 1.5KE440CA which I can't see in the list. Note the 440 part is important as it is the stand off voltage i.e below which the device will not conduct appreciably. If you try anything less with a mains voltage you will see a blue puff of smoke ...

                          In the second link I think the SCK-10502MS could be the one to use for LED inrush protection. Note that these devices are wired in series with the load and work by having a relatively high cold resistance which then drops as the device warms up. A steady state is reached with the resistance at a value comensurate with the temperature for that current but no handy equation is given for this in their data sheet as far as I can see, so its going to be an iterative calculation or just try it and see. Seeing as 6x LED bulbs are not likely to be much more than 42W the current is likely less than 0.2A which is about 10% of the max current rating for the device so it isn't going to blow up. Nonetheless I'd expect it to get warm and probably hot eg. say 50-60C rise (guess).

                          Comment

                          • Karam
                            Automated Home Legend
                            • Mar 2005
                            • 863

                            #14
                            Originally posted by smoothquark View Post
                            I do need to get my QRI sorted - family not happy being dependent on me to turn on and off the kitchen lights using the MCB! My friendly electrician is on holiday as well....
                            Inserting an inrush limiter will help avoid future recurrance due to contact welding (on the assumption that this an accurate diagnosis) but won't solve the present problem of not being able to switch off the lights. If you have spare outputs you can transfer the lighting circuit to these, or at a stretch you might even put them in parallel with another circuit if the two coming on together is less inconvenient than the present situation. But unfortunately oherwise the answer is to replace the QRI.

                            Comment

                            • smoothquark
                              Automated Home Sr Member
                              • Oct 2009
                              • 69

                              #15
                              Originally posted by Karam View Post
                              But unfortunately oherwise the answer is to replace the QRI.
                              Oh! I have sent you an email whether I can return the QRI over to you to see if firstly, the diagnosis is correct, and secondly, whether it can be repaired. I would not want to replace it if possible - cost, and I do have spare outputs on some of my other QRIs and QRHs. I can just use one of the limiters and connect the kitchen downlights to one of the spare QRHs for now and perhaps get the triac versions when available? I am planning to get some LED lights to put on the soffits in the loft to light up the driveway and garden etc and I guess would be better off with a triac version in the loft for that.

                              Comment

                              Working...
                              X