Re: [TCML] Climbing Arcs

[Sfxneon@xxxxxxx]

Hi Marko,
 
The reason is that it adds capacitance to the secondary circuit, which  
causes a voltage rise and ringing (oscillations) at a higher frequency. This is  
very destructive to the transformer, which was designed to operate under load at 
 about 60% of its open circuit (rated) voltage and 80% of its short circuit  
(rated) current. Just running a NST without a load for a while can cause an  
internal breakdown and shorted secondary. NSTs are built with little room for  
error when it comes to proper loading. It will also shorten the life of the 
neon  tubes because of the high current spike from the added capacitance every 
time  the tubes fire (120 times per second). 
 
The situation you describe with having 100 feet of GTO inside the same  
metallic conduit is about the worst case scenario I can imagine. The GTO needs  to 
be as short as possible (no longer than 20 feet!) and run in separate  
non-metallic conduits. Also, running HV AC wiring in metal conduit produces a  lot of 
ozone, which will attack the insulation and eventually cause it to fail  and 
short out. Although the NEC code book approves of GTO in electrical  metallic 
tubing, they are more concerned with fires than improperly loaded  
transformers. 
 
You are going to have to relocate the transformer closer to the neon, and  do 
away with any metal conduit in order to have a reliable installation. If you  
have any more questions, just contact me off list.
 
Tony
 
In a message dated 6/2/2008 5:17:51 P.M. Central Daylight Time,  
kc5gym@xxxxxxx writes:

>Just running the  GTO
> through grounded metal conduit  is a real tranny killer, even in a neon 
sign.

> Tony

Why?
I  am repairing a neon sign and the gto, about 100', two cables side by  side
runs in 1/2" rigid pipe.

Thanks
Marko
kc5gym
 



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