RE: 48kW DRSSTC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Hooper, Christopher AZ" <christopher.az.hooper@xxxxxxxxx>

Hi Steve,

Thanks for the input, I forgot about good old SCR's as made my first
color organ in Physics in 1974! Man they have been around for a long
time. My goal is not to have any heavy transformers in the 48kwatt coil
as my F350 was hurting this year transporting three solid state coils,
boat, camper, etc. Gas is getting $$, so the less I have to pay for gas
to go 2000 miles, the more I can spend on backup IGBT's. I have talk to
Steve Ward about this but I work with NETWORK slice cards and if they
fail, we pull out and drop a new one in, back on line in 30 seconds
(well maybe 60 seconds). Then go back and repair the cards later, This
is what I want to do with the 48Kwatt coil, all on slice cards, one
fails, pull, drop in new and keep sparking! A LED indicates which card
is failing. We did this with microcontrollers we put in the space
station. !

Cheers,
Christopher

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Wednesday, November 30, 2005 1:24 PM
To: tesla@xxxxxxxxxx
Subject: RE: 48kW DRSSTC

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

 > the only thing that has
 > me stumped is how I
 > am going to control a 200 amp voltage double without
 > a heavy transformer/variac.

*ahem* SCRs :-)

I used SCR controlled rectifiers in my OLTC2 and in my
new DRSSTC. The DC link voltage can be varied from
zero to 100% without a variac.

This approach isn't ideal: the controlled rectifier
has lousy power factor at less than 100% output
voltage. Adding inductance in the line improves things
but at the cost of voltage droop under load, and extra
size and weight.

But it's fairly easy to build and get working- it's
just a giant lamp dimmer after all- and SCRs are
almost indestructible. They (along with diodes) are
the only semiconductors you can actually protect with
fuses. Also, at full output voltage, the power factor
is no worse than an ordinary diode rectifier.

This is my original 4kW voltage doubler with 240V, 30A
in and variable 0-600V DC out. Note that us "Limeys"
call SCRs "thyristors".

http://www.scopeboy.com/tesla/ol2psu.html

Steve Conner
http://www.scopeboy.com/