Dry running my primary
IamSmooth, Thu Jan 11 2007, 05:14AMI want to make sure my static spark gaps work properly during power-up. Is it ok to remove the secondary and use a variac to power up my primary circuit to make sure everything is working right? I want to make sure my Terry Filter gap fires above a certain voltage and that my static gap works when I turn off my synch motor. Any problems doing this?
Re: Dry running my primary
J. Aaron Holmes, Thu Jan 11 2007, 09:12PM
I'd start with just the NST and your Terry filter. Open the safety gap very slowly until it *just* stops firing. AFAIK, that is the ordinary way of setting a safety gap. If you run with the Tesla primary circuit (gap+cap+coil) attached and no secondary to suck the juice out of it, the RF currents will go bananas! (I suppose this is a good "test" for your Terry filter, but I wouldn't do it!) Further, this is probably no good for your primary caps, either. High RMS currents are a leading cause of pulse cap death, from what I've heard.
Regards,
Aaron, N7OE
J. Aaron Holmes, Thu Jan 11 2007, 09:12PM
I'd start with just the NST and your Terry filter. Open the safety gap very slowly until it *just* stops firing. AFAIK, that is the ordinary way of setting a safety gap. If you run with the Tesla primary circuit (gap+cap+coil) attached and no secondary to suck the juice out of it, the RF currents will go bananas! (I suppose this is a good "test" for your Terry filter, but I wouldn't do it!) Further, this is probably no good for your primary caps, either. High RMS currents are a leading cause of pulse cap death, from what I've heard.
Regards,
Aaron, N7OE
Re: Dry running my primary
IamSmooth, Thu Jan 11 2007, 10:14PM
That was my feeling which was why I wanted to hear from everyone. I was hoping that someone may have tried this and would know if it damaged their system. I've already set the TerryFilter gap. I guess what I can do is have everything connected and power it up. I'll visually inspect the gaps when it is getting darker outside and see if I can visualize a spark in the right places. For the static gap I'll just shut off the motor and power-up. Once I get a spark I'll turn on the synch motor and see if the static spark is extinguished.
IamSmooth, Thu Jan 11 2007, 10:14PM
That was my feeling which was why I wanted to hear from everyone. I was hoping that someone may have tried this and would know if it damaged their system. I've already set the TerryFilter gap. I guess what I can do is have everything connected and power it up. I'll visually inspect the gaps when it is getting darker outside and see if I can visualize a spark in the right places. For the static gap I'll just shut off the motor and power-up. Once I get a spark I'll turn on the synch motor and see if the static spark is extinguished.
Re: Dry running my primary
Steve Conner, Fri Jan 12 2007, 11:58AM
Running with no secondary is harder on the components. No streamers are there to eat up the input power, so it all gets dissipated as heat in the primary circuit. The spark gap and tank capacitor see higher RMS current, and the gap is more likely to power arc, and the tank cap to overheat. However, if your system is well built to start with, and you keep the runtime short, it should be OK.
When setting a safety gap, it's very important to bring the voltage up smoothly with a variac. If you just flip a switch, it generates a voltage spike which can lead to you setting the gap wider than it should be.
Steve Conner, Fri Jan 12 2007, 11:58AM
Running with no secondary is harder on the components. No streamers are there to eat up the input power, so it all gets dissipated as heat in the primary circuit. The spark gap and tank capacitor see higher RMS current, and the gap is more likely to power arc, and the tank cap to overheat. However, if your system is well built to start with, and you keep the runtime short, it should be OK.
When setting a safety gap, it's very important to bring the voltage up smoothly with a variac. If you just flip a switch, it generates a voltage spike which can lead to you setting the gap wider than it should be.
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