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Re: Chokes vs Safety Gaps
Original poster: Jim Lux <jimlux-at-earthlink-dot-net>
At 07:56 AM 2/9/2004 -0700, you wrote:
>Original poster: Mark Broker <mbroker-at-thegeekgroup-dot-org>
>I fail to see how a ~1mH choke in series with a ~1kH iron-cored
>transformer secondary will provide any protection whatsoever. If used in
>conjunction with an RC circuit, then that could be bad, too.
Speculating here... A difference would be that an RF choke outside the
transformer might be able to take a fairly HV, fast edged transient without
failure. The poorly insulated windings designed for minimum manufacturing
cost inside a NST probably can't. If the external choke slows down the
rise time, then the huge leakage C inside the NST windings won't be as big
a deal, so the voltage in the transient has a chance to be more evenly
distributed within the winding.
>A properly-set safety gap will just barely not fire at full operating
>voltage without the primary capacitor connected, so I fail to see how a
>properly-set safety gap with a properly-tuned and operated TC will be
>ineffective or affect performance.... IME a safety gap will not fire
>unless the TC is out of tune or the power supply is overvolted via an
A gap misfire/mistiming could result in a transient voltage that's somewhat
higher than normal, and the safety gap would fire. Also, things can happen
like "alligator clip falls off primary" or "ground on secondary comes
undone" or "capacitor fails and coil goes grossly out of tune". That's why
it's called a "safety gap".
>My 2 cents.
>Chief Engineer, The Geek Group
>On Sun, 08 Feb 2004 21:24:41 -0700, Tesla list <tesla-at-pupman-dot-com> wrote:
>>Original poster: "Gary Weaver" <gary350-at-earthlink-dot-net>
>>If you adjust the safety gap so it won't fire then it doesn't do anything so
>>why have it. If you adjust the safety gap so it fires then it takes power
>>away from your coil and the discharge sparks get shorter don't want that
>>either. A choke coil provides all the protection needed to protect the
>>transformer from feedback so the safety gaps are a waste of time.