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Thread: QRI Relay Problem

  1. #11
    Automated Home Sr Member
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    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....

  2. #12
    Automated Home Legend chris_j_hunter's Avatar
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    not sure, but this may have been what Karam was thinking-of :

    http://www.rapidonline.com/Electroni...n-Diodes-81128

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

    we also bought some of these :

    http://www.rapidonline.com/Electroni...nrush-Limiters

    none used, yet, though, because it seems our CFLs are reasonably well behaved / controlled (finger's crossed) ...
    Last edited by chris_j_hunter; 28th August 2013 at 10:38 PM.

  3. #13
    Automated Home Legend Karam's Avatar
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    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).

  4. #14
    Automated Home Legend Karam's Avatar
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    Quote 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.

  5. #15
    Automated Home Sr Member
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    Quote 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.

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