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Re: Off Line - DRSSTC (OL-DRSSTC) - 3



Original poster: "Mike" <induction@xxxxxxxxxxx>

Hi Terry,
Regarding your concern for the 185 UF Buss cap, and the ~ 22 amp RMS, can you go to the standard 660 VAC 20 UF caps we use in 480 volt input constant voltage filament transformers? Just motor starter /run caps really, metal case for getting rid of heat, etc. For your value that would be 9.25 caps so a bank of 10 would do if they match this service.
Mike



----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx> To: <tesla@xxxxxxxxxx> Sent: Tuesday, September 27, 2005 8:32 PM Subject: Off Line - DRSSTC (OL-DRSSTC) - 3


Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi All,

I have been running a lot of models and now have this for the OL -DRSSTC concept schematic:

http://hot-streamer.com/temp/OL-DRSSTC-03.gif

I had to go to 60BPS instead of 120 BPS. I use the dead 1/2 cycle to fire the coil so there is no incoming current to quickly recharge the buss cap. Otherwise, once the coil is started, in never turns off!! The waveforms look like this:

http://hot-streamer.com/temp/OL-DRSSTC-03a.gif

It should put out nice 60BPS bursts with 200kV peaks. Very long 2mS duration. Power to the streamer is roughly 1080 watts. The resonant charger gets the cap up to about 520VDC firing voltage with the line and resistive losses (note that the inductor is 19mH now for 60Hz). It is a stunning 25 joules per bang!!!

The primary current is only 200 amps and everything else seems generally easy without massive over loads. The 50 ohm resistors across the gates reduce the gate voltage and act a bit like a dead zone for the IGBT crossover.

The trigger circuit is pretty much out of the SIDAC data sheet...

The only concern is the 185uF buss cap. It will see about 22A RMS! That would kill most single electrolytics so I will have to look into that more.

By changing the SIDAC value, it should work off 120VAC or a variac at lower test voltages too. Everything can be "fiddled with" as needed to make adjustments or to get it to work.

So it is looking pretty good on paper and by computer. I think I will order some parts...

Cheers,

Terry