Electrochemistry: Liquid Power Resistor for 2000VAC
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From: D from BC on 13 Mar 2010 11:57 In article <weOdnViNweT29QbWnZ2dnUVZ_gGdnZ2d(a)posted.localnet>, robertbaer(a)localnet.com says... > > > I thought the voltage rating of those resistors was 150V, not 200V - > so one would need 14 resistors in series; make them 5W and be OK for > "any" time period. mmm.. pile of resistors vs liquid resistor.???. The CuSO4+water resistor does score points for power handling, voltage handing and flexibility(I get every value just add more CuSO4).
From: markp on 13 Mar 2010 13:06 "D from BC" <myrealaddress(a)comic.com> wrote in message news:MPG.260561b419a1f67989702(a)209.197.12.12... > If my junkbox resistor blows up in a jar of water, then I'll try to make > a 100k CuSO4+water resistor. > Then I'll replace that with a power resistor from my next parts order. > I'm not sure I'd use water as the coolant. I'm dubious about using water, the resistor might act as a heating element and boil the water locally, it'll then be surrounded by gas bubbles which will increase further the thermal resistance and the resistor might then overheat. I'd be tempted to use oil instead. Ecnerwal said that they used copper sulphate as the resistive part, then submerged the whole lot in transformer oil. Anyway, let us know how you get on! Mark.
From: D from BC on 13 Mar 2010 13:14 In article <80229uFvk3U1(a)mid.individual.net>, map.nospam(a)f2s.com says... > > "D from BC" <myrealaddress(a)comic.com> wrote in message > news:MPG.260561b419a1f67989702(a)209.197.12.12... > > If my junkbox resistor blows up in a jar of water, then I'll try to make > > a 100k CuSO4+water resistor. > > Then I'll replace that with a power resistor from my next parts order. > > > > I'm not sure I'd use water as the coolant. I'm dubious about using water, > the resistor might act as a heating element and boil the water locally, > it'll then be surrounded by gas bubbles which will increase further the > thermal resistance and the resistor might then overheat. I only need 5 seconds of circuit run time. > > I'd be tempted to use oil instead. Ecnerwal said that they used copper > sulphate as the resistive part, then submerged the whole lot in transformer > oil. > > Anyway, let us know how you get on! > > Mark. I had to insulate the resistor leads.. Tap water was showing some conduction. Cl ions and other ions are present. I could use distilled water but that's another trip to the store. I've put 1240VAC on the 100K 2W in tap water for 5 seconds and alls well. I might go up to 2000VAC at a later time.
From: Archimedes' Lever on 13 Mar 2010 13:19 On Sat, 13 Mar 2010 18:06:45 -0000, "markp" <map.nospam(a)f2s.com> wrote: > >"D from BC" <myrealaddress(a)comic.com> wrote in message >news:MPG.260561b419a1f67989702(a)209.197.12.12... >> If my junkbox resistor blows up in a jar of water, then I'll try to make >> a 100k CuSO4+water resistor. >> Then I'll replace that with a power resistor from my next parts order. >> > >I'm not sure I'd use water as the coolant. I'm dubious about using water, >the resistor might act as a heating element and boil the water locally, >it'll then be surrounded by gas bubbles which will increase further the >thermal resistance and the resistor might then overheat. > >I'd be tempted to use oil instead. Ecnerwal said that they used copper >sulphate as the resistive part, then submerged the whole lot in transformer >oil. > >Anyway, let us know how you get on! > >Mark. > You missed what he said. He said that the resistor's metallic compounds that got dispersed into the water BECAME the resistor.
From: Baron on 13 Mar 2010 14:54
D from BC Inscribed thus: > In article <80229uFvk3U1(a)mid.individual.net>, map.nospam(a)f2s.com > says... >> >> "D from BC" <myrealaddress(a)comic.com> wrote in message >> news:MPG.260561b419a1f67989702(a)209.197.12.12... >> > If my junkbox resistor blows up in a jar of water, then I'll try to >> > make a 100k CuSO4+water resistor. >> > Then I'll replace that with a power resistor from my next parts >> > order. >> > >> >> I'm not sure I'd use water as the coolant. I'm dubious about using >> water, the resistor might act as a heating element and boil the water >> locally, it'll then be surrounded by gas bubbles which will increase >> further the thermal resistance and the resistor might then overheat. > > I only need 5 seconds of circuit run time. > >> >> I'd be tempted to use oil instead. Ecnerwal said that they used >> copper sulphate as the resistive part, then submerged the whole lot >> in transformer oil. >> >> Anyway, let us know how you get on! >> >> Mark. > > I had to insulate the resistor leads.. > Tap water was showing some conduction. Cl ions and other ions are > present. I could use distilled water but that's another trip to the > store. > > I've put 1240VAC on the 100K 2W in tap water for 5 seconds and alls > well. > I might go up to 2000VAC at a later time. Use the condensate from the fridge or a de-humidifier. -- Best Regards: Baron. |