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12V Transformers keep dying

Discussion in 'Electrics UK' started by MenBehavingBadly, 15 Jan 2020.

  1. MenBehavingBadly

    MenBehavingBadly

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    Hi

    Just had a couple of downlighter transformers die (for the same downlight) - anything I should be checking for in the wiring.

    Has 212V between N and L.

    Transformers either side on same circuit are working fine

    I guess I could just have been unlucky I guess but don't want to keep feeding transformers to it

    Thanks
     
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  3. winston1

    winston1

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    I guess you are actually using switch mode power supplies not transformers. Use a real transformer for reliability.

    Better still change the fitting to GU10 and use 240v LEDs thus no transformers required.
     
  4. bernardgreen

    bernardgreen

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    but each LED lamp has a switch mode current source to drive the correct current through the LED element(s) in the lamps.
     
  5. MenBehavingBadly

    MenBehavingBadly

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    Thanks for the replies - they are using Halogens at the moment
     
  6. JohnW2

    JohnW2

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    ... or a capacitor !

    Kind Regards, John
     
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  8. ericmark

    ericmark

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    How quaint, not seen one for ages, however the transformer gives a fixed precent output of input, and the quartz needs to be within a very close tolerance, too hot and filament fails and too cold and the filament material migrates to the quartz so again it fails, so in the main we don't use simple transformers, but a power supply which will compensate for voltage variation, it does contain a transformer but works in kHz range and uses electronics to control it.

    The problem is when the tungsten does fail it can cause ionisation (bright flash) and a very high current flows which can damage the electronics, so common for bulb and transformer to fail together, should not use dimmers with quartz lights, but if used will also often take out dimmer as well.

    Most people have moved to LED which in extra low voltage version are often rated 50 Hz so can't use electronic power supplies in kHz range, plus the power supply often has a lower limit and can't turn down enough to use LED replacements, the LED needs the old type transformer without the voltage regulation, that is built into the LED bulb.

    So most people move to low voltage (230 volt) instead of extra volt voltage as then you can use either quartz or LED.
     
  9. DetlefSchmitz

    DetlefSchmitz

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    So how did people cope with mains powered halogens then?
     
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  10. ericmark

    ericmark

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    The whole idea of extra low voltage quartz lamps was thicker filament to extend life, however volt drop was found to be a problem, so the switch mode control of the transformer was to redress the volt drop problem with for extra low voltage was made worse due to losses in the transformer and high current in the extra low voltage cables, the volt drop problem was not as high with low voltage lights.
     
  11. Taylortwocities

    Taylortwocities

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    All a bit academic as Europe has filed must halogen lamps in the disposal bin.
     
  12. DIYnot Local

    DIYnot Local

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