[chbot] Matthias Wandel, and his amazing exploding SSR

Mark Atherton markaren1 at xtra.co.nz
Thu Aug 23 02:12:13 BST 2018

Might be useful to find out the cold resistance of your load as a 
starting point; this will strongly affect initial inrush.

... and obviously (?) you need to size components around peak current.


On 23/08/2018 12:58 PM, Volker Kuhlmann wrote:
> On Thu 23 Aug 2018 06:33:39 NZST +1200, Mark Atherton wrote:
>> https://www.youtube.com/watch?v=FV9t1GFVbhU
>> What happens when you try and control a 22A electric water heater
>> (presumably 120+120V in Canada) using a cheap 25A solid state relay.
> Oops, thanks for posting that. I had similar plans, although with a bit
> more protection. I have 2 100A versions here... but got them from
> Aliexpress, so they must be good, right...? US$18/2.
> Digikey has Omron G3NA series for around US$100+, and they require a
> massive heat sink.
> The bipolar load switching creates a significant voltage drop. Another
> list member reported that the SSR got only lukewarm without heat sink
> when operated at 10A for the 40A version. Does anyone else have
> experience with this, and with which SSR model?
> The guy who took one apart is wrong on his electrical safety assessment
> though, there ain't 4mm clearance on that PCB...
> 25-40W power loss, big heat sink, 20mA permanent leakage (that's more
> than an old wirewound transformer), me thinks a mechanical relay might
> be better...
> Volker

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