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Re: Dump the RSG!


From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Tuesday, November 04, 1997 2:41 PM
To: 	Tesla List
Subject: 	Re: Dump the RSG!

Greg, all,
             I've been sitting on some Westcode devices (SCRs and 
diodes) for some time now while agonizing over exactly how to use 
them without destroying them. The kind of ratings I am talking about 
(from memory) are 2.5kV holdoff/device (fwd and rev) with current 
ratings around 2kA or so. di/dt should not be a problem with a 
sufficiently low frequency coil. The agonizing bit comes from the 
implications of stacking them. If one turns on fractionally before 
the other (say two stacked), what happens to the sluggard? Bit of a 
worry I think?
    The idea is to use DC charging and use the SCR/s to conduct in 
one direction with the diodes to conduct in the other. This should 
allow a per cycle quench capability with a sufficiently narrow gate 
firing pulse (SCRs recover while diodes are conducting).
    In case you're wondering, I got these things for free. I think 
they were rejects because of differences in gate firing currents.    
Not sure about the diodes. Perhaps they were simply thrown out.
They were supposed to have been used for electric train motor control.
They appear to work OK from quick tests I've done.

Any comments?
Malcolm

> From:   Greg Leyh[SMTP:lod-at-pacbell-dot-net]
> Sent:   Monday, November 03, 1997 4:04 AM
> To:     Tesla List
> Subject:    Re: Dump the RSG!
> 
> Richard Hull wrote:
> 
> 
> > Wow!  That is great!  Just what we have been waiting for!  What catalog can
> > I order a solid state switch that can commutate 20 -50 megawatt pulses with
> > peak currents near 1000amps at 20,000 volts about 500 times per second?  Oh
> > yeah, its gotta cost me no more than my current gap system.
> 
> Unfortunately in this case, better performance and higher reliability 
> do not come at a lower price.  If you want a recent data sheet however,
> contact Westcode Ltd. and ask for the WG20045HP Symmetrical Modified
> GTO.
> 
> V off = 4500V per stacked device
> Ipeak = 80kA
> Irise = 12kA/uS
> I^2*t = 1,600,000.
> 
> 
> -GL