Using SSR with 240V LED 'bulbs'

Discussion in 'General Electronics Chat' started by Paul Ked, Feb 11, 2015.

  1. Paul Ked

    Thread Starter New Member

    Feb 11, 2015
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    Hi there.

    I've been having trouble with a series of SSR's (S202T01F) not switching off properly.

    The circuit I have used is so basic and I have used and RC 'snubber' across the output (22nF + 46R) as the data sheet suggested but can't fathom it out.

    It works for some of LED lights but not all. Any ideas?

    Many thanks and Best Regards

    Paul Ked
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    What power supply are you using? it is unusual to use a triac to switch LED's?
    Have you confirmed the input by removing input voltage when they stay on?
    What about using the SSR ahead of a bridge for the LED's?
    Max.
     
  3. #12

    Expert

    Nov 30, 2010
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    Here's the datasheet:
     
  4. Paul Ked

    Thread Starter New Member

    Feb 11, 2015
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    Reading that back it all seems a bit vague!!

    I am using a 24VDC output from a controller to drive the input of the SSR via a 1k1 resistor and a series LED (for indication). The output is then used to light a GU10 type LED lamp (there are 40 of these in total, so it's like a 40 channel disco controller!) with a snubber across the SSR output terminals.

    The LED lamps are of various manufactuters and different colours, and they don't all behave the same. eg. Some of the lamps will work in all channels, some will turn on the first time they are required to, but then only dim instead of turning off and some have caused the SSR to fail to a 'permanently on' state.
     
  5. Paul Ked

    Thread Starter New Member

    Feb 11, 2015
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    Thanks for that.

    Looking at the Data sheet, will I have to use zero crossing SSR's (so they do turn off during the AC cycle)?
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Most SSR's turn off at the end of the cycle naturally, the zero crossing is detect zero turn ON.
    Max.
     
  7. Paul Ked

    Thread Starter New Member

    Feb 11, 2015
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    Thanks. Do you have any idea what may be holding the SSR "half on"?
     
  8. Paul Ked

    Thread Starter New Member

    Feb 11, 2015
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    I have found the problem...

    As the lamps are by different manufacturers, so their internal circuits differ. The very small leakage current through the snubber circuit is enough to keep some of the led clusters glowing when the SSR turns off (but only after the lamp has been lit). The problem with the SSR failing is probably due to the fact that some of the lamps use transformers to drop the 240V and, I guess, the inrush current has caused them to fail (although the data sheet says they are ok for inductive loads!!)

    The solution...

    Snip the snubber capacitors off the boards... Voila :)
     
  9. #12

    Expert

    Nov 30, 2010
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    That's not in the book about SCR's! o_O
     
  10. Paul Ked

    Thread Starter New Member

    Feb 11, 2015
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    LOL, but it works ;)
     
  11. #12

    Expert

    Nov 30, 2010
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    OK. One of my mottoes is, "Electrons can't lie."
    If the electrons say you're right, that's the end of the conversation.
     
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