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A Question on this NST.

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MikeT1982

Sun Jun 03 2007, 07:44AM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
Location:
Posts: 119

I am curious about this type of NST like this Franceformer in the picture. It only has 1 high voltage bushing and the other little ground seems to go to its case just like a center tap on a regular NST with 2 high voltage bushings...but this one has no center tap. Is the other end of the secondary coil (the one that does not go to the high voltage bushing) actually connected to that little screw AND the case? Seems dangerous in thinking of it! I wonder why these types are made.

Adrian

Sun Jun 03 2007, 10:22AM

Registered Member #697 Joined: Thu May 10 2007, 12:28PM
Location: Australia
Posts: 22

I'd say your right. It's apparently grounded as "One End Ground" which doesnt mean much to me. It has no data sheet and there is little other info about it.

Its a Franceformer 3030/4030/5030 PKM-1 if anyone is wondering...

Coronafix

Sun Jun 03 2007, 10:33AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Wouldn't it just be the same as a MOT?
One end of the secondary is grounded to the core?

MikeT1982

Sun Jun 03 2007, 10:38PM

Registered Member #621 Joined: Sun Apr 01 2007, 12:37AM
Location:
Posts: 119

Yeah that's what I'm guessing, because if the other end of the secondary wasn't connected to anything it couldn't make the 30ma current I'm thinking. The more I think about it, it is really just half of an NST! so its like grabbing the High voltage bushing and centertap of a normal one for power and just cutting the other side off with a hacksaw lol. After posting I kept thinking about it and I'm pretty sure that's what kind of beast this is. (small beast lol).

Billybobjoe

Mon Jun 04 2007, 12:58AM

Registered Member #396 Joined: Wed Apr 19 2006, 12:55AM
Location: Pittsburgh, PA
Posts: 176

Yes, I'd assume this is just a "half" of a normal NST. I don't see how it would be dangerous (well, any more than a regular NST), as the other end of the secondary is at ground potential. As Goldpshere said it's practically the same thing as a MOT, except higher voltage and lower current. They are most likely made for lower voltage applications for smaller neon tubes, where a midpoint secondary grounded NST wouldn't be necessary.

Bjørn

Mon Jun 04 2007, 01:32AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

if the other end of the secondary wasn't connected to anything it couldn't make the 30ma current

Everyone repeat after me:
a stands for are, a unit of area.
A stands for ampere, a unit of current.

Yes it is easy to understand anyway but if we get into the habit of doing it wrong we will soon write things that can be misunderstood. Particularly by people that are still learning.

Bored Chemist

Mon Jun 04 2007, 05:56AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Look on the bright side Bjorn, he didn't use megamps. Also, if everyone learns the rules (ie that if it's a unit named after a person it gets a capital and if it's a prefix bigger than 1 it gets a capital too) We will miss out on peple bragging about their new 'scopes that are slower than a chart recorder.
BTW, what's 10 to the minus eighteen of an are abreviated as?

Coronafix

Mon Jun 04 2007, 06:23AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Bored Chemist wrote ...

... if everyone learns the rules (ie that if it's a unit named after a person it gets a capital and if it's a prefix bigger than 1 it gets a capital too)

What about kilo (k)?

...

Mon Jun 04 2007, 02:32PM

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

I am guessing that the reason that your NST has only 1 post is either because it was cheaper to design it like that, or because there was a patent/etc dispute between them and someone else. You should be able to wire it in like any normal NST, just use the gnd tap as the other HV out, and don't ground anything in the primary circuit (except for the NST itself).

edit, woops don't let me post from my CCNA class anymore. For us you need a lower case k, kV, kHz, (as opposed to a cisco router which expects a capital K in when referring to such things as clock frequency, or sizes measured in thousands of bytes)

Steve Conner

Mon Jun 04 2007, 02:51PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

No, kilo always took a small k. Binary kilo (1024) is big K, or Ki these days.

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