Re: Remote Power Supply Connection

Trevor Wilson wrote:
"Ian Thompson-Bell" <ruffrecords@xxxxxxxxxxx> wrote in message news:g0up1a$1ap1$1@xxxxxxxxxxxxxxxxxxxx
Trevor Wilson wrote:
"Ian Thompson-Bell" <ruffrecords@xxxxxxxxxxx> wrote in message news:g0rmo0$27co$1@xxxxxxxxxxxxxxxxxxxx

I agree when the rectifiers are close to the transformer supplying them but not when they are separated from it my a couple of metres of cable.
**And again, it is not difficult, nor expensive to deal with such issues. A handful of capacitors will effectively deal with any problems.


Definitely not. The point is that the caps normally used to suppress reverse spikes in semiconductor diodes do just that. The have no effect on the forward current spikes which are significant.

**No.


Denial is not much of an argument.

With remote ac
supplies these current spikes must pass through the cable and they will cause serioes radiation. Any attempt to stop them happening will simply stop the rectifiers from rectifying. That is why is is essential to have the rectifiers close to the transformer.

**No.



Denial is not much of an argument.
http://www.arcadvisor.com/faq/dc_direct_current_arc.html

This clearly shows that at low currents (e.g HT currents) and high
voltages (e.g.HT voltages) dc arcing is very unlikely to occur.
**Remind me: How much energy is able to be stored by large (unstated values)
capacitors?

0.5*C*V^2

In a 100uF capacitor at 300V that's a mere 4.5 joules. Not worth worrying about.
**Points:

* 4.5 joules is a substantial amount of energy.
No it isn't. it is 4.5 watts for one second.

**Yes, it is. It depends on how long it takes to charge/discharge whatever capacitance is on the other side of the connector. In 0.1 Sec, that is 45 Watts. In 0.01 sec, that is 450 watts. Certainly plenty of energy to damage surface treatment of most connectors. And, as I stated earlier, lots of builders use considerably more capacitance than 100uF and more than 300 Volts for their power amps. 1,000uF and 700 Volts is not unheard of. And THAT is a considerable amount of energy.

My small rotary hammer drill
is rated at 2.5 joules per strike and can pulverise bricks.
And there you have hit the nail on the head. It is not the *amount* of energy but the *rate* at which it is consumed that matters.

**EXACTLY my point. 4.5 joules consumed in 10msec is a *lot* of energy for thinly plated connector to cope with.

No, 4.5 Joules consumed in 10mS is not a lot of energy, it is a lot of power.

Cheers

Ian
.

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