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Re: Large Transformer Question w/ Formula (fwd)
---------- Forwarded message ----------
Date: Sun, 15 Feb 1998 02:25:30 +1100 (EST)
From: Rodney Graham Davies <Rodney.Davies-at-anu.edu.au>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: Large Transformer Question w/ Formula
Hi Guys,
On Fri, 13 Feb 1998, Tesla List wrote:
> Jeff and all,
>
> Tank cap size is a function of the transformer's output voltage and the
> operating frequency. The higher the output voltage, the larger the
> current capability needed. A rule of thumb is about 0.01 uF for every 60
> mA off a 15 kV transformer. For example, the following table can be used
> for approximate sizing:
>
> uF uF
> Max -at- Max -at-
> kV mA 60 Hz 50 Hz
> == == ===== =====
> 9 30 0.008 0.011
> 9 60 0.018 0.021
> 12 30 0.007 0.008
> 12 60 0.013 0.016
> 15 30 0.005 0.006
> 15 60 0.011 0.013
>
> The table can be scaled for larger current values as appropriate.
>
> Hope this helps!
To make things easier on others who don't have a voltage & current
setting on the above table, use this formula.
1
C = --------------
2 * Pi * F * R
Where, C - Farads
F - Mains Frequency in Hz (ie USA - 60Hz, Aust - 50Hz)
R - Impedance of transformer (V/I) Ohms
eg. NST rated 10,000V 30mA
V = 10000 volts, I = 0.03 amps
R = V / I = 333333.333 Ohms
This is an ideal formula for matching a capacitor with your transformer
for resonant charging (maximum efficiency).
Catchya!
Rod