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SCR's above 2,200 volts?

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Yanom

Thu Aug 30 2012, 10:03PM

Registered Member #4659 Joined: Sun Apr 29 2012, 06:14PM
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I was looking at SCRs on Mouser.com (the only electronics supplier I've found that has a sane, searchable catalog, where you can search by part values and ratings, not just maker / part number), and the highest voltage SCR they sell is 2.2kV. I later found a few others that went up to 3kV, but they were obscenely expensive - on the order of several hundred USD. Is this as high as SCR's go or can I get higher voltage SCR's for a reasonable price? They don't have to be high current.

Harry

Thu Aug 30 2012, 10:19PM

Registered Member #4081 Joined: Wed Aug 31 2011, 06:40PM
Location: UK
Posts: 139

Try Digikey, I found a few there

2Spoons

Thu Aug 30 2012, 11:39PM

Registered Member #2939 Joined: Fri Jun 25 2010, 04:25AM
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You are heading into thyratron territory there. Have you considered them? Saw a 20kV russian one one ebay for $50.

Yanom

Fri Aug 31 2012, 02:38PM

Registered Member #4659 Joined: Sun Apr 29 2012, 06:14PM
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2Spoons wrote ...

You are heading into thyratron territory there. Have you considered them? Saw a 20kV russian one one ebay for $50.

Aren't thyratrons essentially polarized triggered spark gaps ("Trigatrons")? With all the noise and loss of efficiency that entails?
That would probably be O.K, though.

Dr. Dark Current

Fri Aug 31 2012, 03:32PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
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Posts: 3384

I think SCRs are made up to some 6kV, but those are the big puck ones with kiloamp ratings.

Steve Conner

Fri Aug 31 2012, 04:11PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
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Posts: 6706

SCRs are quite easy to stack in series anyway.

Patrick

Fri Aug 31 2012, 05:38PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

as steve connor suggests, SCR's are one of the few silicon devices that can be scaled, like in the small TO-92 all the way up to the huge hockey puck ones. They're are super tough, and tolerant of much abuse, so long as you dont let the gate teminal/silicon section overheat or overvolt.

As has been stated, you can series and parallel them since there so abuse tolerant. gate trigger for high speed does take some power, so theyre not like mosfets. (you can kill the gate so be careful)

i have a bunch of the 50RIA60 SCR's which i like.

SCR, 50RIA60 from international rectifier, sourced from digikey.

there are some differences like phase control SCR's vs the switching ones, but you can work around that, either way. It may not be advantagous to go dropping big $ on big SCR's, it might be wiser to choose a mid-sized bolt/stud one, buy in bulk that same type and parallel/series them as needed, then youll have spares and lower cost at the same time.

you might need a minimal RC (RCD maybe?) ladder network to balance the series/parrallel devices. that depends on your intent though.

Yanom

Fri Aug 31 2012, 10:09PM

Registered Member #4659 Joined: Sun Apr 29 2012, 06:14PM
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Posts: 158

wrote ...

there are some differences like phase control SCR's vs the switching ones,

I've seen these words before. What is the difference between phase control and switching?

wrote ...

you might need a minimal RC (RCD maybe?) ladder network to balance the series/parrallel devices. that depends on your intent though.

What's the proper setup for 2 or 3 in series? I'll be discharging an (about) 100uF 3kV capacitor through a 11ohm, 45mH induction coil and I need the SCRs for switching.
oh, and is this the RC / RCD you're talking about?
Connection

how does that work?

Patrick

Fri Aug 31 2012, 10:39PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Yanom wrote ...

wrote ...

there are some differences like phase control SCR's vs the switching ones,

I've seen these words before. What is the difference between phase control and switching?

Like the triac in a dimmer switch , there are many uses at the kw and Mw level where turning on a sine wave is needed, then clipping it. or allowing a 0 to pi, or pi to 2pi, is needed for low loss switching for motors and generators and what not.

Yanom wrote ...

wrote ...

you might need a minimal RC (RCD maybe?) ladder network to balance the series/parrallel devices. that depends on your intent though.

how does that work?

yeah shooting caps is what SCRs and vacuum tubes are good for, IGBTs and MOSFETs dont live long in cap discharge applications. Thats about the circuit i thought someone might find, it looks good to me, but youll have to experiment.

You want a low impedance--high engery source tobe dischagred in very short order through a low resistance load, with the rate of current rise being determined by that small inductance value... and seriesing SCRs is how i would do it.

youll also need two gate drives, at least one isolated and elevated to that upper SCR... Im hung over at the moment so ill be able too explain better when my brain comes back.

Yanom

Fri Aug 31 2012, 11:02PM

Registered Member #4659 Joined: Sun Apr 29 2012, 06:14PM
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Posts: 158

Patrick wrote ...

youll also need two gate drives, at least one isolated and elevated to that upper SCR...

This?

All the SCR's have to turn on simultaneously in order to share the voltage amongst them, right?

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