[AMPS] Re: Surge voltage, HV connectors.

[Tom Rauch]

Hi Wilbert,

> Perhaps I should have clarified. There is no capacitor or rectifiers. All
> waveforms are sinewave AC. The test load is a string of lightbulbs. The
> magnetic shunts have been removed.

That is not a good direct indicator of transformer performance under 
high power factor loads, such as a capacitor input supply. It is a 
good direct indicator of choke input supply performance, assuming 
the choke is correct in the final application.   

> Transformer ESR=(2093-2038)/0.4 = 137.5 ohms.

That amount of ESR is intolerable in a typical capacitor input 
supply for a HFPA. THe ESR has to be a tiny fraction of the load 
impedance change to supply what is normally considered 
acceptable regulation. 
 
> The transformer sags 2.7 % under projected full load (which includes line
> sag)

Only with choke input.
 
> > A choke input will help, because the supply will draw current over
> > virtually all of the cycle with the correct size choke. Peak current can
> > be reduced by a factor of 10 or more.
> 
> It seems to me that the oven transfomer itself is good enough. After all,
> it handles the load with little sag. 

You don't have the planned "load" on the transformer! The actual 
peak load current is many times more than the current you are 
subjecting the PA too.
 
> Hmm...Perhaps I should ditch the oven transformers and get something with
> the correct ESR made up...I will have to think about this.

ZL2AAA rewinds them, and gets a nice supply. 

> > both sides of the line float with no CT reference to earth, although you
> > have a safety ground. I had a specific conversation about that with two
> > ZL's. Was I misinformed?
> 
> Very much so. I hope those guys aren't practising electricians in ZL2....
> The mains here is multiple earthed neutral, typically 235 V, 50 Hz.

If the mains are earthed, why couldn't I measure zero volts from 
one side of the line to ground? If they are earthed at the center tap, 
why aren't the lines 120 V from each side of the line to earth?

Ian, what's the status in GB? 
 

73, Tom W8JI
w8ji@contesting.com

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