Xfmers-60Hz to 50Hz

From:  Jim Lux [SMTP:jimlux-at-earthlink-dot-net]
Sent:  Saturday, May 09, 1998 10:40 AM
To:  Tesla List
Subject:  Re: Xfmers-60Hz to 50Hz

> ----------
> From:  Hollmike [SMTP:Hollmike-at-aol-dot-com]
> Sent:  Friday, May 08, 1998 6:58 AM
> To:  tesla-at-pupman-dot-com
> Subject:  Re: Xfmers-110 to 220 (fwd)
> Jim,
>    I was reading your response about the 50Hz effect on transformers.  I
> under the impression that most transformers were designed to handle 50/60
> I would not think that a neon would be harmed by 50Hz.  Don't may coilers
> remove shunts to allow their neons to put out more current?   Would this
> have the same effect as using 50Hz without removing the shunts?  Comments
> welcome.
> Mike Hollingsworth.

It depends on the how cost sensitive the application is. We've bought
transformers and motors, and the like, that were specified for 60Hz only.
Sort of ragged edge designs where you want to eke out the last few tenths
of a cent in iron. I don't think that a neon would be harmed, any more than
by overloading it by 20%. Of course, the people who remove shunts have
depotted the transformer and are typically immersing it in oil, a much
better cooling technique than a lump of tar.

Of course, a typical NST is designed to work over a wide temperature range,
including the proverbial hot summer day at 40 degrees C. So, even if you do
overload it to the tune of 10-20 degrees worth, you are probably running it
at 20-25 C case temp and it still won't be too hot. Also the relatively low
duty cycle of a tesla coil (rarely do you run your coil for hours on end)
helps. I suspect the thermal time constant of a NST is in the at least an

Yes, running at 50 Hz is sort of like removing some shunts, as far as
current limiting goes, in that both techniques lower the effective reactive
impedance in series. There is also the eddy current (iron losses) issue to
consider with 50Hz. 

In most cases, your typical NST is probably overdesigned a bit, if only to
account for manufacturing and installation variations. They are hardly
precision devices.

I would just run them at 50Hz, and if it starts to smell like burning tar
or varnish, decide that I had made a mistake.