[Amps] PS Theory ?

[rlm]

>rlm wrote:
>>**  Ian -- Does the PSU Designer program have an entry for Mains 
>>Resistance?.
>>
>Well, kind-of. It has a little calculator where you can work out the 
>effective secondary resistance, which includes the real secondary 
>resistance plus a contribution from the primary resistance plus the 
>mains resistance.
>
***  sounds good but if the transformer core is not Hipersil®, there is 
an additional loss due to flux coupling.  

>If you have a figure for mains resistance, you can add it to the primary 
>resistance.
>
>>How does one measure this quantity?  Thanks.
>
>1. Connect an accurate AC ammeter between the mains supply and your 
>biggest amp, 


***  Only those amplifiers that use a resonant-choke filter read mains 
current correctly on a garden-viriety AC ampmeter.

>or some other large 220-230V appliance.
>
>2. With the load switched off, use a high-resolution RMS AC DVM to 
>measure the off-load voltage V1, just upstream of the ammeter.
>
>3. Wind up to full load, and then measure the current I and the on-load 
>voltage V2 (which will of course be lower).
>
>4. R = (V1 - V2)/I.
>
>
>
>-- 
>73 from Ian G3SEK