Re: Mains conditioners and power cables
- From: "Arfa Daily" <arfa.daily@xxxxxxxxxxxx>
- Date: Thu, 01 Sep 2005 08:16:08 GMT
"Nick Gorham" <nick@xxxxxxxxxxx> wrote in message
news:43169ee2$0$12892$cc9e4d1f@xxxxxxxxxxxxxxxxxxxxxx
> Arfa Daily wrote:
>
>>
>> * I'm having a bit of trouble with that one. A larger capacitance will
>> certainly try to increase the * initial charge current over the first few
>> cycles as the power supply comes up, which if allowed, * may exceed the
>> peak forward current capability of the rectifier diodes. However, in a
>> * transformer derived supply, the effect will be mitigated by the natural
>> current limiting effect of
>> * the transformer's secondary and to a lesser extent, primary, winding
>> inductances. Any
>> * resistance in the windings, or in the form of surge limiter resistors,
>> will also contribute to the
>> * charge current limiting.
>>
>> * Once the capacitor is charged, the ripple will be reduced by the
>> effectively lower source
>> * impedance of the increased value of capacitance. This effectively means
>> that the capacitor is a * bigger bucket, better able to supply the load's
>> current requirements, which haven't changed
>> * from when a smaller value was fitted. This, it only needs to do, of
>> course, between cycle
>> * pulses from the rectifier. As the bucket won't drain down as far during
>> these pulse gaps, it will * take less energy to fill the bucket back up,
>> not more.
>>
>
> 1.It will take exactly the same enery to "fill up" as the same amount has
> been removed by the amplifier running with the same current requirement.
>
> 2.However as the capacitance is higher, removing the same energy per cycle
> will produce a smaller voltage drop.
>
> 3. But because the voltage drop is smaller (2), the angle that the diodes
> conduct over will be smaller.
>
> Therefore as the diodes have to provide the same energy as before (1), but
> over a smaller time (3) the peak current MUST be higher.
>
> --
> Nick
Hmmm. Thinking on this some more, that sounds kinda right ( sorry Tim !! ).
Obviously as the same amount of energy has been taken out, the same amount
will need to be put back in. I must have been having a brainstorm, but it
had been a long hard day...
Thanks for putting it a bit clearer for my poor addled old brain to get
itself around, Nick.
Arfa
.
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