Gene, I’m one of those nuts who still builds electronics that use vacuum tubes. While incandescent light bulbs are nearly gone, tubes are not. The heaters in the tubes are just like those old lights and don’t like the higher AC voltage. The solution is to place an (about) 1 Ohm power resistor in series with the heater circuit. The exact resistance depends on details.
I didn’t know about the 13th power but it seems about right after some calculator button punching. Tubes can cost from $10 to $30 each so liftime kind of matters. I usally set the heaters to run 5% under nominal voltage and they will last basically “forever”, or “thousands of hours”. I’ve been applying you observation in the other direction. A standard light dimmer would make an old hot-filament light bulb run forever, It makes an ugly waveform but the bulbs don’t care, they just see the lower peak voltage. Modern lights all run off voltage-regulated power supplies. Any time you can use a regulator, the higher AC volts only improve power distribution efficiency. Less i-squared-r loss. > On Jun 25, 2024, at 4:22 PM, gene heskett <ghesk...@shentel.net> wrote: > > On 6/25/24 16:24, Viesturs Lācis wrote: >> otrd., 2024. g. 25. jūn., plkst. 17:17 — lietotājs Todd Zuercher via >> Emc-users (<emc-users@lists.sourceforge.net>) rakstīja: >>> >>> Hang on here, back up a bit. Start at the beginning. What is the input >>> voltage on the name plate for the entire machine? What voltage are you >>> feeding to the machine? For example if the machine's name plate calls for >>> 400v, but you are feeding it 460v, that would explain having about 30v too >>> high voltage at the servo's transformer. Does the machine have a large >>> transformer in it similar to this that the main power goes through? >>> >> This got me curious and I checked what my multimeter thinks of mains >> voltage. It was showing 405VAC where it is supposed to be 380VAC. And >> I was thinking that this is multimeter error rather than entire >> powergrid being 25V higher, but little search on web revealed that our >> national standards require voltage tolerance of +/- 10%. > > Within my lifetime since I wired the house my stepfather was building for us > at the tender age of 12, when the REA wired the country after WW-II, the "std > wall socket" voltage delivered from the pole pigs that feed our houses, has > risen from 110 volts, to 127 volts, each time paid for by the shortening of > the life of our incandescent light bulbs. So the "220" grounded center-tap > drop feeding our services now reads 254 if your meter is accurate, not the > 220 in the vernacular. In case anyone wonders, the life of an incandescent > light bulb is determined by the 13th power of the applied voltage. Your > trivia factoid for the day. >> Hope for the best, plan for the worst - Peter, what do you think about >> rectifying 232VAC 3-phase for 8i20? > > That, not allowing for rectifier losses, would be 327 volts. Peter possibly > would have some other considerations. >> Viesturs >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > Cheers, Gene Heskett, CET. > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author, 1940) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
