Re: Line Conditioner to Protect Electronics
By Claus Kucher
Robbie Rhodes wrote in Mechanical Music Digest 97.01.08:
> ... but I think the more likely cause of failure is the voltage
> surge when the mains of a neighborhood (e.g., one square kilometer)
> is abruptly disconnected from the regional mains system during a storm.
[snip]
> ... Surges of more than 600 volts, lasting tens of milliseconds,
> are observed on American 120-volt mains. The available current during
> this short period is monstrous: it's equivalent to the transformed
> current at the power-pole fuse before the disconnect event.
Yes, this can be true from some technical viewpoint.
But, the truth is more complicated than some figures on a voltmeter or wave forms on an oscilloscope can tell. Did you ever think of the fact that somebody could touch even an Austrian 230 VAC line and say there is nothing, while others could more likely come to death? No, no -- not the simple thing, I do _not_ mean the pole with zero voltage, instead I speak from the counterpart.
Stomp on yourself if you say you know what's going on. Okay, they tell us there are electrons, positive and negative charges, and electric current can only happen mainly together with some metal things. Sure, capacity as well as inductance of an electrical network is a given fact, resonating can take place, and so on. Someone found out that interrupting such a network at the point of zero of a +/- wave could even be the worst case.
They do not lie, but : Ever heard of the small and tiny *animals* of current doing the _real_ work? No doubt, they hate plastic and like cool metal. And of course, they have a good knowledge of, let's say, what is the difference between common copper and precious platinum; moreover, they do everything for gold! Okay, that's simple too.
So what will happen in case of an interrupt of their normal work during that boring flow from electric power plant to some ordinary refrigerators? Guess there will be a big _panic_!
Due to the small size of their outline and due to the fact that in the first microsecond they know nothing from the break, besides the immediate loss of guidance from their big generator or the nearby also big trans- former. The result is, obviously, no one can expect all of them can hold the predicted 120 (American) or 230 (somewhat European) volts.
Therefore, here you will have 815 V, and some hundred meters afar a minus 314 V -- but only for some milliseconds. Because all the loads -- burning lamps, refrigerators and ventilators, ac-to-dc-transformed motors for player pianos (!) too, and so on -- due to an unknown reason, refuse entry for all of the small and tiny animals of current.
Yeah, this is normally the real problem; but only for a small time. Because after that small period of time the running motors will remember their turning movement and takes as much animals as he can -- but rapidly suffers from the delivery of more of them, and the story comes to an end -- _finito_ -- zero volts on both ends of the electric lines within milliseconds.
I could tell you more about their life, e.g. the special situation where large groups of animals cannot decide to go right or left on the cable -- on your oscilloscope you can see non-sinusoidal waves with high amplitudes (if you can trigger it!). But sorry now, it is too late, maybe another time.
Claus Kucher
[ My goodness! We must continue this discussion off-line, Claus!
[ Do get a good night's sleep first! ;-)
[
[ The American test specification ANSI/IEEE C62.41-1980, prescribes
[ "class A and B" surge wave forms, which power line conditioning
[ equipment must receive as input. I'll try to locate the spec and send
[ it to you via fax. Certainly there is a similar European document.
[
[ -- Robbie
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(Message sent Fri 10 Jan 1997, 03:06:54 GMT, from time zone GMT-0100.) |
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