Page 1 of 2 12 LastLast
Results 1 to 10 of 15

Thread: QRI Relay Problem

  1. #1
    Automated Home Sr Member
    Join Date
    Oct 2009
    Posts
    65

    Default 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?

  2. #2
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,670

    Default

    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; 26th August 2013 at 12:40 AM.

  3. #3
    Automated Home Sr Member
    Join Date
    Oct 2009
    Posts
    65

    Default

    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!

  4. #4
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,670

    Default

    >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; 26th August 2013 at 09:39 AM.

  5. #5
    Automated Home Sr Member
    Join Date
    Oct 2009
    Posts
    65

    Default

    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.

  6. #6
    Automated Home Legend Karam's Avatar
    Join Date
    Mar 2005
    Posts
    817

    Default

    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.

  7. #7
    Automated Home Sr Member
    Join Date
    Oct 2009
    Posts
    65

    Default

    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.

  8. #8
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,670

    Default

    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 ... ??

  9. #9
    Automated Home Legend Karam's Avatar
    Join Date
    Mar 2005
    Posts
    817

    Default

    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)

  10. #10
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    Location
    North Lancashire
    Posts
    1,670

    Default

    this takes a look inside a CFL :

    http://www.cliftonlaboratories.com/compact_fl.htm

    and another look at inrush current :

    http://www.powerbox.info/ssl/inRushCurrent.asp
    Last edited by chris_j_hunter; 28th August 2013 at 11:51 AM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •