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Wiring a nst

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LAN_403

Fri Jun 15 2007, 08:39AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

hi, i just got a nst for free

But i don't know about how to wire it up. i have taken some pictures of the inside. The specs are... sec.15000v. 30ma. primary 240volt 50hz. The first picture is of the whole setup. The second is something that i don't know of. it says on the white thing. Neolite Neon
OCM-B
Amps 1.5-2.5 voltage 240 ac
It also says center secondary tapped to earth.
Can someone help me. Thanks

UPDATE: i took the white thing off and found the two primary terminals. So do i need to use the white thing? Also when i whack the white thing it feels like there is a spring or something in there, Could it be current limiting?

Sulaiman

Fri Jun 15 2007, 09:11AM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141

Assuming the part just out of view on the right in your top photo is either a switch or a fuse
then it's already correctly wired up.

Most important - check the earth wire is a good connection to the case - all the way from the plug to the case.

The voltage between the two high voltage connectors is 15 kV
The voltage from each connector to earth/ground/case is 7.5 kV
The high voltage winding has a center-tap to the case.

Move the neutral wire on the left away from the high voltage terminal.

The first thing you need is a switch far from the NST to allow you to operate safely.

Start with a Jacob's Ladder to get a feel for high voltage.

If you keep the mains ac wires far from the high voltage wiring you should be fairly safe
But do not be tempted to come in contact with the high voltage
it probably will not kill you but it could harm you (burns, violent jumping across the room etc.)

Fri Jun 15 2007, 09:23AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

Thankyou, so do you know what the white thing is? Also there is a piece of enameled copper wire connected where the earth is, Is this just for extra connection to the case?
UPDATE: i have tried the nst but it doesn't have any output, nor does it hum. It doesn't do anything, but for some reason it's not popping the breaker so the primary must be ok. I hooked the two prongs of the jacobs ladder to the high voltage terminals, Is that right. I am am thinking i'll get another nst.

sparky

Sat Jun 16 2007, 02:26AM

Registered Member #530 Joined: Sat Feb 17 2007, 07:56AM
Location: Victoria BC, Canada
Posts: 178

No....your too early to be getting another NST... I bet there is a GFI thats messing up the inputs. Try finding the primary inputs then put 240V through them. I bet you'll find that the NST isn't dead.... the primary should at least produce a humm...

...

Sat Jun 16 2007, 02:39AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

I think you are too inexperienced to be playing with a NST, while you probably won't kill yourself with 30ma it is still extremely dangerous to be playing with when you have no clue what you are doing.

How thick is the enameled copper wire? It is a small (like 30+ awg) that is the center tap to the output, and should be grounded. If it is large (like less than 14awg) then it is a part of the primary and needs more investigation.

In any case, make sure that the terminals of your Jacobs ladder are close enough to each other that they an ark will for with 15kv (I would make them like 1/8" apart to be sure).

Also, I would put a jumper across that white box in the middle, I am not sure what it does but it probably isn't necessary...

Sat Jun 16 2007, 02:52AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

well now it has decided it will work. i took off the white box wired the 240 volt to it and it makes little arcs about 3mm long, but that surely isn't 15 kv, so i believe there is some internal shorting/arcing going on in there. Oh and also the two pieces of enameled copper wire were the secondary centre tap to earth. Is there still something wrong? the arcs start at about 2mm and only stretch to about 3mm, That surely isn't 15kv? oh well i'm getting another one tommorow, but still, if any one knows why i am only getting 3mm sparks from a 15kv nst, please let me know

hmmmm, i guess no one knows what the little white box is?

GreySoul

Sat Jun 16 2007, 07:46PM

Registered Member #546 Joined: Fri Feb 23 2007, 11:43PM
Location: Albuquerque, NM
Posts: 239

If it's got a spring in it then it's most likely either some sort of thermal protection or some sort of user safety device that cuts off power when the top panel is removed.

Of course that's purely speculation. if the NST works when you bypass the mystery box I would be tempted to just remove the box, take it apart, and see how and to what end it ticks.

What I do to diagnose a used NST is plug it in and use a high voltage jumper wire to see if I can strike an arc from each terminal to the case. If I can pull a 10mm arc it goes home with me.

...anyways... double check your wiring, make sure nothing is shorted outside the box....

if that dont work you "could" de-pot the coils and try to fix them.... or you could scrap it and get another NST that is known to work.

-Doug

Sat Jun 16 2007, 10:03PM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

Yes, well i just found out OCM stands for open circuit monitor, so what does that do?
3mm sparks from a 15kv 30ma nst couldn't be right. I thought it was internal shorting, because the secondary windings get warm after about 10 seconds of use? i'm getting another nst today and the guy that giving it to me is going to test it for me, and i'm going to show him this one. Oh, and the 3mm arc is between the two high voltage terminals, which would be 15kv right? Actualy i did open it up and found the big lump of tar, but it was all cracked and fragile, so maybe it has over heated and some of the secondary windings have been damaged?

IamSmooth

Sun Jun 17 2007, 04:04AM

Registered Member #190 Joined: Fri Feb 17 2006, 12:00AM
Location:
Posts: 1567

Why don't you do as previously suggested and see if you can draw an arc to the case from each terminal. If one does not draw an arc then you know that it is that half of the secondary that is dead.

Again, make sure you have a good ground to the case.

Sun Jun 17 2007, 05:25AM

Registered Member #809 Joined: Wed May 30 2007, 08:59AM
Location: Melbourne, victoria
Posts: 114

well i got another one exactly the same, but it worked allright when i first started it but now it only makes sparks on contact. Here is a video i found on you tube of the same transformer except it's the 60ma version. http://youtube.com/watch?v=A0hzpUDpYIc mine should look like that except mine only makes 3mm at the most sparks and the new one only makes contact sparks

this is really starting to annoy me, i need someone to have a look at it for me, they are just not working, is there any internal circuits in there eg;fuses. Its wired as the pic in my first post but without the white thing, there are two pieces of ennameled copper wire coming out the side which i guess are the secondary centre taps, which are earthed, and the arcs are between the two high voltage terminals which should be 15kv right?

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