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Re: Chris T's NST question...

>Date: Sun, 27 Sep 1998 07:02:55 -0600
>To: tesla-at-pupman-dot-com
>Subject: "Underloading" an NST
>From: Tesla List <tesla-at-pupman-dot-com>
>
>Original Poster: AuroraOne-at-webtv-dot-net 
>
>I have seen numerous posts recently warning against "underloading" an
>NST by running it without a load connected to the high voltage
>secondary.  I have been having some problems getting an NST, but thanks
>to the helpful hints of many people on the list, I may soon be the 
proud
>owner of one.  Anyway.....here's my problem/concern:
>     I am working on a project in which I would like to attempt to
>transmit a high voltage current though a conduit filled with inert gas.
>Sound familiar?  Yes, this is a sort of "home-made" neon lamp tube,
>except that I will be using a flexible rubber tubing provided with a
>system of valves and gauges to release/add gas, instead of a permanent
>glass tube.  I won't go into details here, but I'm doing this for a 
very
>specific reason.  I was planning to  transmit the 15 kv current from 
the
>transformer directly thourgh the tube.   But, since many on the list
>have warned that an NST was not meant to run "unloaded" for a long
>period of time, is there any way I can use the transformer to provide
>the high voltage without risking breakdown?  In other words, how can I
>arrange this experiment so that it provides a "load" for the
>transformer? 
>
>After going through all this trouble of getting this thing, I certainly
>don't want to burn it out!
>
>Thanks!
>Chris T.



  Neon sign transformers are made for, as the name suggests, running 
Neon Lights.
 If you use it to run your rubber conduit filled with inert gas it will 
be doing exactly what it was designed for, with no stress or anything. 
This is because the high voltage of the NST is only required for 
ionisation of the gas. After it becomes conductive, it will require a 
far lower voltage (typically less than 1KV) to remain lighten.
 Overvoltage conditions only occur when there is no load on the NST's 
secondary, because without a load the voltage will be allowed to rise. 
An ionised gas will provide some load to the transformer (because it had 
some resistance) and therefore the voltage will be kept down to a safe 
level. Just make sure you have enough gas to provide your NST with 
enough resistance. A 500mA unit usually requires some 20 inches or more 
of gas to work at a safe voltage level. The 1kW units can run over 50 
inches of ionised gas...
 The higher the voltage, the more gas it will ionise (i.e. the longer 
the tube can be), the higher the amperage and the brighter the lights 
will be.
 Hope this helps...

 Sam Barros.

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