[Amps] PS Theory ?

[Ian White, G3SEK]

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.

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, 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         'In Practice' columnist for RadCom (RSGB)
                            Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek