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Title: Water resistors and other Loads Post by: KB2WIG on January 22, 2006, 10:10:45 PM Back when I was a young JN, the schol put me in the industrial electricity lab to keep me out of trouble. While doing some experiments, we would use a water resistor for some of our load. We was workin with DC rotary equiptment-- 150VDC, 80A per unit. manual starters. adjustable ckt breakers... lots of laughs setting up the pretty Cu arc. Now that I have to PAY for my own toys, does anyone have any suggestions for testing HV power supplies.. I don't want to fire up my ART-13 withought testing the B+ on something else... I dont want to series lamps if I dont gotta... Anyone got any comments/ideas???? klc
Title: Re: Water resistors and other Loads Post by: WA1GFZ on January 23, 2006, 10:09:46 AM Put the supply on a variac and fuse and go for it.
Title: Re: Water resistors and other Loads Post by: WBear2GCR on January 23, 2006, 12:41:32 PM Sorry, I gotta ask. What is a "water resistor" exactly?? ::)
Pure water happens to be an insulator. Add salt (etc.) and it becomes a weak conductor... I'd been eyeing that title for three days now, finally I had to look, and ask! ;D _-_-bear But, yeah a variac, ammeter and voltmeter on the B+ is a good way to go - of course, if you have rectifier tubes, you'll perhaps want to make a provision to feed the primary of the B+ xfrmr from the variac, or else temporarily replace the rectifier tubes with solid state diodes... Title: Re: Water resistors and other Loads Post by: KB2WIG on January 23, 2006, 01:54:20 PM Thanks guys.....
I guess i'll go with the variac and fuse route....I have some nice oil cans (23uF@4KV) and some 10uF@2KV. I wanted to try various configurations to get around 1.2KV for my project. i guess i'll go the trial by fire routine.. I like to bake things before I set them into metal. I cant let the pure water thing go... Yes pure, non ionized water is an insulator. But, water is amphiprotic- that is, water molecules transfer protons between each other, which is results in H30+ and OH- ...... Which is a really, really really small small shift to the left on the pH scale..... Add some Beer and a discussion of acid rain and a Monty Pythin abuse/argument session devolves... Good for parties.... anyway, Water resistor.... I should have kept my mouth shut...... Picture a industrial mop bucket on weels made up of very thick bucket walls. Then picture a chain with a window weight looking electrode attached. The bucket wall is ground and the window weight is attached via a conductor to the devices B+. The water is distlled water with a chemical to act as an electrolyte. The chain part is attached to a 'crank' wich raises/lowers the electrode into the fluid, thereby varying the resistance..The electrolyte is generally a salt; maybee copper sulfate ( will not have much reaction with a copper conductor). Gud for large loads... The other types are used for High Voltage..... Tesla at Colorado type high voltages. they use long tubes filled with electrolyte.... Title: Re: Water resistors and other Loads Post by: NE4AM on January 23, 2006, 01:55:45 PM Hoo boy. I had some experience with this years ago, testing a 12 KV, 100 KW shortwave modulator. (COMMERCIAL GEAR, NOT FOR HAM USE!) Lessons learned: AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
#1. All hardware in the water must be stainless steel, or else electrolysis will make short work of it! #2. Huge amounts of H2 and O2 _will_ be liberated. You have the potential for a nasty explosion unless the H2 is dealt with properly! Be careful, OM! |