[Amps] PS Theory ?

[Ian White, G3SEK]

rlm wrote:
>
>
>>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.
>
That's not something PSU Designer can handle, but it's usually not a 
major source of error. If you want to quantify it, you'd have to go 
beyond PSU Designer's simplified 'plug-and-play' approach. You'd have to 
make some loss and leakage inductance measurements on the transformer, 
and step up to a full SPICE model.

>>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.
>
Sorry, I should have specified an RMS AC ammeter as well as an RMS 
voltmeter.

Come to think, there's also the question of power factor, because the 
amp probably looks quite inductive at light loading, but as it draws 
more current the PF gets better.

>>or some other large 220-230V appliance.
>>
If you insist on a resistive load, bring the cooker into the shack :-)


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
                            Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek