General > General Technical Chat
Lightswitch trashed in only a few weeks...
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capt bullshot:
The problem is the inrush current of all these LED power supplies, not arcing when turning off.
Each time the switch closes the circuit, the DC bulk capacitors charge and cause a rather high current surge across the switch. Sometimes this just welds the contacts together (it's difficult to switch off then), sometimes it quickly degrades the contact materials, as to be seen here.

One could use the switch to control a contactor that in turn switches on the LED lights. The contactor would have to be appropriately rated for the rather large inrush, otherwise its contacts could stick together, too.
Whales:

--- Quote from: peteb2 on August 25, 2022, 05:36:14 am ---In that mill-second as the Mains goes away the circuit regulates like mad trying to maintain its feed to its load & keep running. Thus it draws an increasing current even though it's collapsing away though & with multiple fittings it all adds up to an arc across the opening switch contacts.... Well at least that's what it appears like.

In simple terms we're burning up the switch worse than when the same device was switching old flouros on & off....

--- End quote ---

Hmm OK.

The 400V cap will be sized to be able to survive at least 10msec of no power (this is the distance between peaks at 50Hz).  If it couldn't do that then it would have horrible flicker.  Actually many LED fixtures do seem to flicker madly, so you could be onto something here  ;)

Theoretically speaking 10msec should be enough because the switch will probably stop arcing after around 10msec (due to the zero crossings).    But if it's already got too small of a capacitor (and is hitting it with lots of stress current) then this might make sense.  Not sure.
wraper:
Frankly this switch looks like something from 70 years ago.
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