Re: Magnifier Primary Capacitors - EQUIDRIVE vs. STANDARD

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Bert Hickman <bert.hickman-at-aquila-dot-net> 

Tesla list wrote:

>Original poster: "gtyler" <gtyler-at-drummond-dot-org.za>
>Some time ago I designed a 120 Kv SMPS for X-ray use. The transformer
>and output rectifier was in oil in a molded glass-fibre box. If I ran it
>with the lid off the oil would "jump" out the box at full voltage, and
>circulate violently at a reduced voltage. A materials science professor
>from a local university was also involved in the project and even he
>could not explain why this happened. Anyone have any ideas?
>George
>  > Fascinating!!  Oil can "flow around" and re-deposit charges as needed
>to
>  > neutralize things...  So cool!!!!
>
>.

Hi George,

This phenomenon is called electrohydrodynamic flow. It's similar to ionic 
wind seen in air, and results from the transfer of charge into the 
insulating liquid. Dielectric fluids are "propelled" away from the regions 
of high stress into regions of lower stress. In the process, the fluid at 
the electrode-fluid boundary becomes electrostatically charged, repelled, 
carrying excess charge away from the boundary.

As charge is carried away it forms regions of space charge that alter the 
overall charge distribution within the dielectric fluid. And under the 
influence of very high E-fields, fluids can actually form high velocity 
jets, and spherical droplets can shed excess charge by ejecting  a jet of 
small droplets.

While this phenomenon appears to be beneficial for equalizing stresses 
across capacitor modules in a pulse cap, it can have undesirable 
consequences within high voltage transformers. As Dr. Resonance indicated, 
thermally and E-field driven flow of electrically charged oil has lead to 
long-term insulation damage and failure in large power transformers.

-- Bert --
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