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Testing a Silicon Controlled Rectifier (SCR)

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Ignoramus22440

Jan 1, 1970
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I have a "dual SCR" that is pictured here:

http://igor.chudov.com/projects/Welding/11-New-Rectifier/dscf0004.jpg

The one I am talking about is in the middle. It is a International
Rectifier IRKT Magn-A-Pak. It has no model number on it, I think that a
sticker fell off or something. The other two are TT170N and I have a
nice datasheet for them.

Anyway, I know for a fact that it has a sufficient amp rating for what
I want to do with it. What I do not know, is whether it has a good
enough voltage rating. I want to rectify up to 220 VAC.

The datasheets are here:

http://ec.irf.com/v6/en/US/adirect/ir?cmd=catNavigate2&punchInID=295

and they show these thyristors start with 400 volt rating.

What I am not sure is whether a 400V thyristor can be safely used to
rectify 220V AC. I understand that peak voltage is going to be about
300 volts, within the 400V rating, but perhaps there needs to be some
"extra safety room" for voltage?

So... If the answer to the previous paragraph is yes, if I need that
extra room, how would I test this magn-a-pak to make sure that it can
block more than 400 volts?

The next rating after 400 volts, is 800 volts. Plenty enough for me. I
want to make sure that this IRKT is at least 800 volts. Right?

I could, perhaps, apply 400 VAC to its AC input and test the plus
terminal vs. the other side of the transformer supplying 400 VAC.

400 VAC xfmr, contact 1 -----> AC input of thyristor ----> DC+ output
of thyristor ---> multimeter ----> 400 VAC xfmr, contact 0. The
multimeter should show 0 volts.

Would this be a sensible test procedure?

i
 
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