Ballast Vs. Arc output
skyler, Sun Oct 25 2015, 09:17PMI have been working on a tesla coil, but I am confused why a ballast increases the output, while no ballast leaves us with practically no arcs.
Here is a clip without any ballast:
Here is a clip with one secondary shorted MOT
Here is two MOTs used in parallel with each other for a ballast
I thought a ballast should just be used to prevent your circuit breaker from popping due to too much current... Why is the ballast making the output have larger arcs than with no ballast??
What ballast can we implement to have the best arcs?
Re: Ballast Vs. Arc output
omegalabs, Tue Oct 27 2015, 08:59PM
A little more information would be useful.
I know only one case, when this could happen, but not with MOTs.
We used a low drop pole transformer about 16kVA and 5%, and because its low drop, the spark gap was arcing and there was no output. I placed a big resistance on the primary side (a lot of hairdriers) and it gave immediately 1,5m spakrs without any other thing changed.
But it's not the case with your coil, as MOTs are internally current limited, their drop is around 20-50%. Maybe something in your circuit is arcing over from the excess voltage.
omegalabs, Tue Oct 27 2015, 08:59PM
A little more information would be useful.
I know only one case, when this could happen, but not with MOTs.
We used a low drop pole transformer about 16kVA and 5%, and because its low drop, the spark gap was arcing and there was no output. I placed a big resistance on the primary side (a lot of hairdriers) and it gave immediately 1,5m spakrs without any other thing changed.
But it's not the case with your coil, as MOTs are internally current limited, their drop is around 20-50%. Maybe something in your circuit is arcing over from the excess voltage.
Re: Ballast Vs. Arc output
skyler, Wed Oct 28 2015, 04:45AM
May it have to do with the asyncronous spark gap? It seems like the arcs are even failing to bridge the gap on the Spark Gap when the tesla coil is activated without a ballast.
skyler, Wed Oct 28 2015, 04:45AM
omegalabs wrote ...
A little more information would be useful.
I know only one case, when this could happen, but not with MOTs.
We used a low drop pole transformer about 16kVA and 5%, and because its low drop, the spark gap was arcing and there was no output. I placed a big resistance on the primary side (a lot of hairdriers) and it gave immediately 1,5m spakrs without any other thing changed.
But it's not the case with your coil, as MOTs are internally current limited, their drop is around 20-50%. Maybe something in your circuit is arcing over from the excess voltage.
A little more information would be useful.
I know only one case, when this could happen, but not with MOTs.
We used a low drop pole transformer about 16kVA and 5%, and because its low drop, the spark gap was arcing and there was no output. I placed a big resistance on the primary side (a lot of hairdriers) and it gave immediately 1,5m spakrs without any other thing changed.
But it's not the case with your coil, as MOTs are internally current limited, their drop is around 20-50%. Maybe something in your circuit is arcing over from the excess voltage.
May it have to do with the asyncronous spark gap? It seems like the arcs are even failing to bridge the gap on the Spark Gap when the tesla coil is activated without a ballast.
Re: Ballast Vs. Arc output
GrantX, Wed Oct 28 2015, 07:12AM
I'm not sure how likely any of those are, but without pictures of the setup I can't think of much else.
GrantX, Wed Oct 28 2015, 07:12AM
skyler wrote ...
May it have to do with the asyncronous spark gap? It seems like the arcs are even failing to bridge the gap on the Spark Gap when the tesla coil is activated without a ballast.
What sort of power supply are you using? I'm assuming its a stack of MOTs, since you are using some for ballasting. If you have an open-circuit voltage of only ~4kV you might have trouble getting the gap to fire reliably. How large is the capacitor? I had a situation once where the tank capacitor was far too small for the amount of current the supply could push, and it resulted in the spark gap forming hot power arcs. If it's too big your supply may struggle to charge it before the gap electrodes line up. Or you might have a situation where the combined inductance of the ballast MOTs and the tank capacitor are causing the voltage to ring up slightly beyond the turns ratio, allowing the gap to fire more consistently. May it have to do with the asyncronous spark gap? It seems like the arcs are even failing to bridge the gap on the Spark Gap when the tesla coil is activated without a ballast.
I'm not sure how likely any of those are, but without pictures of the setup I can't think of much else.
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