Current / Voltage regulation

in article snipped-for-privacy@corp.supernews.com, James at snipped-for-privacy@jamesvarga.com wrote on 8/31/04 6:14 PM:

From my meager knowledge of plating electrochemistry. only the low range will be of interest to you unless you put a number of your plating vats in series. That is done in the aluminum smelting industry.

What are your regulation reqirements and why? I would guess that a single transformer with thyristor phase control would be good enough. Polyphase rectifiers would be better if ripple were a problem. Because of the low electrochemical voltages used, semiconductor drops will lower efficiency if vats are not in series.

Bill

I was thinking - could i just use various 1ohm say 25W resistors inline with the + to vary this?

snipped-for-privacy@jamesvarga.com

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you already have voltage control... so just add a series load to put the current about where you want it. i have used light bulbs and electric oven elements as high power resistors. even a space heater in series might work. auto headlights for low voltage work might be what you want.

but as you say the current rating is .5 to 50A does that mean it has adjustable limiting? (otherwise the current would be 0 to 50)

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If the minimum current is .5A, then put a resistor across the output to deaw at least that much. R = E/I.

To limit the current, just get some high current lamps like 12V headlamps and put them in series with the + output lead. One headlamp might be 20A, so put another across it with a switch so you can have 20A or 40A. You could use smaller lamps for less current, each with a switch. Voltage isn't a problem, as others stated you will probably need the low voltage range.

It HAS a current reg circuit (or should have).Does it have knob(s) labelled voltage, current or smthg.like that?Does it have gauges?It's not a beast.Real beasts are aluminium industries, that make aluminium out of bauxite (the most power-hungry industry probably).They are linked directly to the HV grid (150 kV here).Also >7,5 MVA (which is the largest MV supply available here).

-- Dimitris Tzortzakakis,Iraklion Crete,Greece major in electrical engineering freelance electrician dimtzort AT otenet DOT gr Ï "James" Ýãñáøå óôï ìÞíõìá news: snipped-for-privacy@corp.supernews.com...

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---------- Actually aluminum smelters (specifically those that I am familiar with) run at 600 to 1200 VDC and 50 to 100MVA per potline . Sure the incoming lines are at 150 or higher KV but this is stepped down to the 13-15 KV level then at each line dropped down again to the lower voltage and rectified. Depending on the potline (and when it was built) the current may be 50,000 to 100,000 Amps. Your "beast" is quite small. -- Don Kelly snipped-for-privacy@peeshaw.ca remove the urine to answer

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I worked on an steel smelter in Vera Cruz Mexico, an 200 MVA plant. Do not know the primary or secondary voltages, just that you could FEEL the arc from 200 yards away.

in article N1E%c.172730$Lj.89765@fed1read03, SQLit at snipped-for-privacy@cox.net wrote on 9/8/04 6:45 AM:

The main point of using an electrical furnace for steel is to obtain heat in a clean way. an ac arc is probably ok although I do not really know.

For aluminum, the electrical energy is REQUIRED for electrolytic reduction of aluminum in solution. To some extent, the carbon electrodes help in the reduction process by combining with oxygen, but carbon is not a suffiently strong reducing agent without a boost from electricity. Aluminum was first produced using potassium or sodium as reducing agents. Those, produced electrolytically themselves, would not require an electrical boost.

Bill