[AMPS] Re: Surge voltage, HV connectors.

[Wilbert Knol]

Hi Tom and others,

Thanks for the comments on the HV supply. I have decided to go back to the 
drawing board, having realised it would have been a lemon.

> 
> ZL2AAA rewinds them, and gets a nice supply. 
> 

Unfortunately the oven transformers have had their stacks welded. The 
laminations are welded together across the core in a couple of places, 
presumably to stop humming. So I can't recycle the cores either.

Anyway, chances are I need something better for the low ESR 
required....higher permeability material etc. The handbook mentions custom 
wound C-cores of high grade (hypersil?) material. Now I know why...

Something else...I always thought the point of having laminate stacks was to 
reduce eddy currents. Wouldn't welding the core defeat that purpose?

> If the mains are earthed, why couldn't I measure zero volts from 
> one side of the line to ground?

Just checked: between neutral and earth: 210 mV RMS.
Between phase and earth: 234 V RMS.

You may not have prodded deep enough to get a contact...they are fairly wel 
recessed. A DVM would have been all over the place, with one probe floating.

> If they are earthed at the center tap, 
> why aren't the lines 120 V from each side of the line to earth?

The nice thing about the American system is that, if you grabbed one of the 
two lines, you'd still only be seeing 60 V RMS.

Wilbert, ZL2BSJ



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