Converter In-Rush Thermistors etc, UPDATE -4

ken white wrote:

BFL13 wrote:
How about this sort of looking one, under the big heat sink overhang on the right by the fan, marked, "D25XB 60 B 7508"

https://www.google.com/search?q=diode+bridge&rlz=1C1CHFX_enUS511US511&espv=210&es_sm=122&tbm=isch&tbo=u&source=univ&sa=X&ei=8TeZUtegG9XboASskYGQDg&ved=0CFQQsAQ&biw=1920&bih=950&dpr=1#facrc=_&imgdii=_&imgrc=1_v16p2X8sJMRM%3A%3B9h-9s0kAu824YM%3Bhttp%253A%252F%252Fi00.i.aliimg.com%252Fphoto%252Fv15%252F902863610%252F10A_15A_50_1000V_GBU_diode_bridge.jpg_350x350.jpg%3Bhttp%253A%252F%252Fwww.alibaba.com%252Fproduct-gs%252F902863610%252F10A_15A_50_1000V_GBU_diode.html%3B329%3B350

That is a pretty durable device, your other part.

For a 25 amp part, it looks like it can handle about 50 amps for 100 cycles and I would probably stick with 50 amps as a conservative number.

Have fun...

Getting back to this, where did that 50a come from anyway? (I see the 60 number for part is not a rating just an identity)

If I want to use my 2R thermistor, then if I get my amps to go with the 170 from where that 50 came from, then I would need to use 85a.
Why can't I use 85 instead of 50? If I did, would I get 60 cycles instead of 100 before it failed? Cycles of what anyway?

The 170v comes from peak volts RMS on 120v line voltage, ? , so that means every time you do a cold start, the voltage could be anything from peak to zip which means in rush may be small or great each time.

So whatever thermistor I pick, I could do several starts and it would work every time but that proves nothing, because it may be that I never caught it at peak inrush, but the next time I could and it could blow? So just because it works great after a repair, that proves nothing?

Meanwhile we do see my thermistors blowing but no harm to the diode bridge, or at least not so you would notice. Which brings us back to the spec about handling stress for 100 cycles. A cycle of what? Does that mean you get 100 starts and then anytime after that your diode bridge might fail? Converters are supposed to last years and years so that can't be right.

(I have not forgotten the comments that the production 100amper design for the straight converter version may not work quite right for the same thing used with variable voltage where perhaps higher inrushes might occur. They might need two different designs, no idea. Might hear something about that from them or not. )