Re: [TCML] Bombarder transformer grounding

[sfxneon@xxxxxxx]

Kevin,
 
I have an old 7.5 kVA SOLA bombarder with slide choke that I'm using  on my 
8" coil and it has worked very well so far, although it is center tapped  
to ground. 
 
_http://ImageEvent.com/thepacratz/teslacoil/8inchcoil_ 
(http://ImageEvent.com/thepacratz/teslacoil/8inchcoil) 
 
Bombarders are not as robust as pole pigs when it comes to overvoltage or  
continuous duty at maximum ratings because they lack the oil for insulation 
and  cooling, but can be pushed way beyond their ratings for short periods 
of time.  (Some of the newer ones like my 15 kVA neon bombarder are now 
potted in  asphalt.) If the choke gets hot during extended runs, use a fan to 
help keep it  cool. It should make a great Tesla coil transformer and 
controller.
 
Most older bombarders were wired with the HV center tapped to ground  
(between the two HV windings), but most all have a floating secondary now, which  
reduces the chance of flashback into the vacuum manifold. Yours is probably 
 floating if it's less than 20 years old or so. Just measure the resistance 
from  the HV posts to ground to find out. A safety gap at the transformer 
will  probably work just fine to protect it from overvoltage. 
I think I would connect the bombarder's case and core to the mains  ground 
and not the TC ground to be safe. 
 
Happy Coiling!
 
Tony Greer
Special Effects Neon
Lubbock, Texas 
_______________________

In a message dated 1/13/2010 8:16:03 A.M.  Central Standard Time, 
makinglightning@xxxxxxxxxxx writes:

I have a Voltarc/Hyde (Willick Engineering) 30KV 250ma 7.5KVA bombarder  
transformer that I am planning on using for a teslacoil.
It comes with a  big slide choke.

>From talking with an engineer at the company, it  sounds like neither the 
primary or the secondary are grounded to the core at  all. The thing looks 
like 2 big coils wound over the primary. The core is  just a big rectangle 
with the primary and secondary on the same side. I am  guessing that the 
secondary winding starts from the outside of one coil,  goes down to the 
middle, near the primary, hops over to the inner side of  the other coil, 
and 
then would back out.

I am wondering how I would  hook up the grounds on a Terry filter and other 
parts of the system. It is  not the same as a neon transformer where the 
windings are connected to  ground on one end. Right? Do I use just one leg 
of 
a Terry filter?
Which  ground would I hook the core of this thing to?

I would like a clear  picture of how the whole thing should be hooked up 
and 
how the grounds  should be hooked up to things here.

I know it is not in oil like a pig.  But with a big terry filter should it 
hold up better than a neon  transformer? Then again, it is not potted. It 
sure looks beefey. Overall it  is 19 x 15 x 10 and weighs an awefull lot. 
Not 
counting the terminals. What  is the concensus here, should I use this for 
a 
coil?
I thought I remember  someone here on the list using one of these on a coil 
 
once.

Kevin
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