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Re: NST question 30ma or 60ma not sure?
Couldn't you measure the open circuit primary current too and take it
away from the shorted current, in order to exclude any losses ?
Tesla List wrote:
>
> Original Poster: "Reinhard Walter Buchner" <rw.buchner-at-verbund-dot-net>
>
> Hi Scott, Neal,
>
> > Original Poster: Bunnykiller <bigfoo39-at-idt-dot-net>
> > Hi Neal you can do the reverse amp check ...
> > short the hi V> outputs and read the amps the 120V
> > source draws and work the amps backwards from
> > 15KV if you get a really oddball reading ( not 30 or
> > 60mA ) then try the numbers with the secondary side
> >at 12KV and repeat the numbers see how that turns
> >out ...
>
> I donīt think this will work correctly. You MIGHT be able
> to tell if it is a xx kV 30mA or 60mA NST, but you wonīt
> be able to tell if it is a 15kV/30mA or a 12kV/30mA (same
> goes for the 60mA version). A transformer is ONLY lossless
> in the theoretical world. In practice you will have all sorts of
> losses. You also donīt know how *exact* these xformers
> are. The sign doesnīt care if it is being supplied with 15kV
> or 14.5kV (for example). The voltage breaks down anyway,
> once the sign gas has been ionized and starts conducting. The
> same goes for the current output. It could be anywhere from
> 25-35mA for a 30mA jobber. This holds even more true, if the
> NSTs are from different manufacturers or different lots (DOP).
>
> The easiest way is to take a meter and really measure the output
> current. DO NOT touch the meter or the leads. You can use a
> DVM, BUT switch it to the highest (10-20A) range. This is the ONLY
> way to measure the current as the meter will act as a true short
> ONLY in these ranges. The 10A or 20A range uses a 0.1 or 0.01
> ohm measuring resistor. The lower ranges (200mA) WILL NOT (!!!)
> save your meter. Usually the 10A or 20A are not fused (it says so on
> the housing, near the 10A or 20A jack). DO NOT use any meter with
> a fuse inside. If the fuses blows, you will have HV all over the SMD
> electronics inside your DMM and you might as well chuck those bucks
> right out the window (it IS the safer and less spectacular way to get
> *rid* of any excess money you might have ;o} ).
>
> Coiler greets from Germany,
> Reinhard