first time with a rotary sg

Kristian, Wed Oct 17 2007, 10:53PM

I'm trying to figure this out. I'm running four mots in series. With my static gap, I usually ballast this down to about a 25 amp draw from the mains, as they will pull 45 amps or more without the ballast. With this synchronous gap, my four mots running without any ballast is drawing less than 15 amps. How does this work? How does using this rotor limit the current so drastically?
Re: first time with a rotary sg
Kristian, Sun Oct 21 2007, 04:39AM

Could someone please shed some light on this for me please.
Re: first time with a rotary sg
Sulaiman, Sun Oct 21 2007, 09:41AM

There's not enough info. for a definitive answer, but my guess is;
with the rsg the spark-rate is lower, hence the primary capacitor is charged less frequently.
OR
with the static spark gap setup you were getting a lot of wasted power in the spark gap.
Re: first time with a rotary sg
Kristian, Sun Oct 21 2007, 03:56PM

So it could be that the rotary gap is just that much more efficient? The static gap I was using is made from three 1.5 inch copper tubes, 3 inches long, well quenched with a vacuum motor. JavaTC calculated 117 bps with this gap. The rotary gap is a 4 inch g10 disk with 4 flying electrodes rotating on a 3" diameter path and two stationary electrodes, all 1/4" tungsten. The motor is a teletype salient pole. The break rate is 120 BPS. I tried varying the tank cap value up and down but that didn't effect the current draw at all. I knew the rotary gap would be more efficient, but I wasn't expecting this.
Re: first time with a rotary sg
Dr. Dark Current, Sun Oct 21 2007, 04:03PM

Kristian wrote ...

So it could be that the rotary gap is just that much more efficient? The static gap I was using is made from three 1.5 inch copper tubes, 3 inches long, well quenched with a vacuum motor. JavaTC calculated 117 bps with this gap. The rotary gap is a 4 inch g10 disk with 4 flying electrodes rotating on a 3" diameter path and two stationary electrodes, all 1/4" tungsten. The motor is a teletype salient pole. The break rate is 120 BPS. I tried varying the tank cap value up and down but that didn't effect the current draw at all. I knew the rotary gap would be more efficient, but I wasn't expecting this.
well, is the output from the coil the same as with the old sg? if so I would say that the rotary is just more efficient
Re: first time with a rotary sg
Kristian, Sun Oct 21 2007, 04:17PM

The bang energy has noticeably increased. Multiple streamers jump from all over the topload, even with a breakout point, and usually find the strike rail. There was arcing all over the secondary and primary until I backed the coupling off a bit. The arc length has not been effected much.