> I have a bunch of Fotek SSRs, rated 385V / 40A. > > Well, that's what it says on the label. > > Perhaps I have been hanging around with Americans too long, but I > recently bought a bullet-casting melter. I wasn't happy with the > temperature controller, so I modified it with a PID controller and > SSR. > > https://photos.app.goo.gl/mq4NFtVtiSsVHFSk9
There is lead in the bucket? > (A variant of that 1/32 DIN controller has a built-in 5A SSR, which > might be an easier modification, but I used the relay / ssr driver > version: https://www.ebay.co.uk/itm/193179699038 ) > > I measured the cold resistance of the element at 111ohms, so that's > nominally 2A, or 3A if we allow for the actual peak mains voltage. > > So I figured that the 40A SSR should be fine. Imagine my surprise when > it failed short-circuit almost immediately. You know what effect lead have on cognitive performance? > It was potted up, and when I pulled it apart the actual driver chip > fell apart, so no way to be sure what the actual rated current was > now. The last one of these I took apart had a 10A driver, so that is > what I have been mentally rating them at. Perhaps I was wrong. > Possibly it's a fake 10A driver in a fake 40A SSR? With 230Vac or so and 111ohms DC resistance should be slightly above 2Arms, less than 3A peak, then inductance may lower current further a lot of margin. Thyristor/Triac may fail to turn off if there is to much inductive load unless a snubber capacitor is added to limit dv/dt and think it is common to use these in SSR. > If you are wondering why a resident of the UK wants a bullet mould, I > have been making tiny glass-bottomed peter tankards: > https://photos.app.goo.gl/RHmiUKG1BtCT5qW16 Sure. > -- > atp > "A motorcycle is a bicycle with a pandemonium attachment and is > designed for the especial use of mechanical geniuses, daredevils and > lunatics." > — George Fitch, Atlanta Constitution Newspaper, 1912 > > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
