Re: NST Pulse Voltage

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Your core (with its current windings) can only support a specific
Volt*second product before it saturates.  The NST will likely not take
more than 20% more input voltage before saturation is reached.  Once
the core saturates, no more input energy will be transfered to the
output, so there is no gain.

It *is* possible to run the NST at a higher frequency, thus allowing
more Volts for less seconds (the V*t product is per half-cycle of
operation, and assuming the core resets before the next cycle).  So
running at 120hz rather than 60hz will let you put in 500V for 20kv
out.  I think insulation lifetime would be an exponential function of
voltage.  It will work for a long time at only a few % over its
ratings, but too much more and the lifetime would be *greatly*
reduced.  Probably not worth the risk.  You'd also need either an
inverter or maybe a generator type power supply to develop the higher
frequency desired.  As far as i know, iron starts to get pretty lossy
past 1khz or so, but this is only an assumption based on the fact that
you dont commonly find iron cored transformers operating above 400hz.

Steve

On 8/13/05, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: "Chris Rutherford" <chris1@xxxxxxxxxxxxxxxxxxx>
>
> Hi List,
>
> Has anyone ever researched insulation breakdown during short bursts
> of higher voltage AC?  Although my NSTs are rated at 250Vin 10KVout,
> what would be the maximum voltage that it could withstand for between
> one and ten seconds at a time?  i.e. 1KVin for 2 seconds.  What are
> the insulation break down characteristics?  I would like to
> experiment but its not a test to be taken lightly.
>
> Thanks
>
> Chris R
>
>
>