- Is this a fuse? - 3 Updates
- New Wind Farms Cheaper Than Even Existing Coal Plants - 9 Updates
- Full wave voltage reading - 13 Updates
| tabbypurr@gmail.com: Jul 11 12:40PM -0700 On Thursday, 11 July 2019 15:44:25 UTC+1, Bob Engelhardt wrote: > held by another 2 screws, each with a sleeve, flat washer, lock washer, > & nut. What were they thinking? > Thanks for your in-depth reply. Something that shape will fuse at higher i than wire the same width due to heat conduction away from the hotspot. The shape improves the slow to fast fusing current ratio, but worsens the breaking capacity. NT |
| Jeff Liebermann <jeffl@cruzio.com>: Jul 11 04:04PM -0700 On Thu, 11 Jul 2019 10:43:34 -0400, Bob Engelhardt >It's a Ward Leonard (no model number) - yeah, I never heard of them >either and I didn't find anything on the web. They did make variacs for >theatrical lighting, so that's probably where this came from. Google finds plenty of hits on the company name, but none involving a variac. Probably parts of a system as you suggest. >> magnet. >It's non magnetic. Following your powerstream lead, I'm guessing it's >tin, or lead-tin. Ok, it's not iron. It's also not 63/37, 60/40 or 50/50 Sn/Pb, also known as solder. I would guess 100% tin with the dull coloration that looks like lead be tinning, or some kind of corrosion. >> shows that #16 AWG will fuse at: ... >AWG 18 is .0403 diam & tin fusing current is 13A. Which is considerably >less than the 20A that the variac is rated for resistive. I would expect the fuse to be rated at MORE than 20A. Also, a 0.017 in thick spade lug is rather flimsy and will probably make a lousy push on tab terminal. For 20A, it really should be thicker or the tab terminal will arc, loosen, and/or fall apart. Tin is easily soldered. I would therefore expect wires to be soldered to the tabs and not use push on terminals. >> Or, you could just replace it with an external 35A cartridge fuse. >Yeah, I put in a piece of 14ga copper & will use an external fuse. For >now, I'll just rely on the 15A breaker that it's plugged into. That will work. I would heavier wire to a fuse socket. However, I'm at a loss as to how to rate the fuse. My initial guess(tm) would be 20A or slightly larger to correspond to the stated rating. However, if the fuse were too large, the variac winding would probably blow before the fuse, which kinda defeats the purpose of having a fuse. Therefore, I would measure the variac copper wire diameter, calculate the fusing current from the Powerstream chart, and size the fuse to blow at LESS than wire fusing current. >was. The mounting block had to be removed (2 screws) & the fuse was >held by another 2 screws, each with a sleeve, flat washer, lock washer, >& nut. What were they thinking? My guess(tm) is if the fuse blew, the variac would be considered totalled and require a factory replacement. That fuse was obviously not intended for customer replacement. My conspiracy theory is that someone forgot to design a fuse into the original device, and had the variac winding blow up in the field. UL or the equivalent, probably wouldn't like Ward Leonard modifying the design without having the device recertified. Not wanting to go through that ordeal process again, WL installed a fuse where UL wouldn't see it and said nothing about the field failures. >Thanks for your in-depth reply. Y'er welcome. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
| Michael Terrell <terrell.michael.a@gmail.com>: Jul 11 09:07PM -0700 On Thursday, July 11, 2019 at 10:44:25 AM UTC-4, Bob Engelhardt wrote: > held by another 2 screws, each with a sleeve, flat washer, lock washer, > & nut. What were they thinking? > Thanks for your in-depth reply. If it was made for stage lighting, the panel would have a fuse per fader (Variac). Stage crews would replace blown fuses with anything that would restore the lights, so a hidden fuse prevented a fire from an overloaded fader. The early ones I used in high school and working on school equipment used Edison based screw in fuses. You would find 30A in place of 15 or 20A, and dead faders. |
| tabbypurr@gmail.com: Jul 10 04:00AM -0700 > https://www.1000bulbs.com/product/207639/PLT-11204.html > Peter Wieck > Melrose Park, PA And you expect the same lpw from domestic lightbulbs? :) NT |
| tabbypurr@gmail.com: Jul 10 04:02AM -0700 > And, I may as well rub it in some: > https://www.1000bulbs.com/product/201937/LED-8038E40-A.html 142.8 lm/w. $37.82 per lightbulb lol. A different animal to domestic lights. Not worth looking at the rest. |
| tabbypurr@gmail.com: Jul 10 04:04AM -0700 > Wind turbines do not pretend to use all the energy available. They use a very small fraction of it - but it is essentially "free" energy. > Peter Wieck > Melrose Park, PA Free energy eh. No, it's expensive energy. Wind is free, but capturing it & making electricity is not by any stretch of the imagination free. I wish it were, but it isn't. NT |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Jul 10 05:32AM -0700 What do you do? Sit around and stew, the explode into meaningless rambles? Cost (installed) per watt, commercial scale: Solar: $2.30 Wind: $1.63 Natural Gas: $0.89 Nuclear: $5.00 - $8.00 Coal: $5.30 ("Clean" technology) On reliability (Add emphasis is mine): Reliability of wind turbines has improved with time and has achieved an availability of---> 98%,<--- but wind turbines fail at least once per year, on average, with larger wind turbines failing relatively more frequently. A recent study of US wind turbines found that when all sources of downtime are accounted for, the average wind turbine actively generates power for 1.5 days between downtime events and that the average downtime is 1.6 hours. Point being that a wind "farm" does not rely on a single turbine, but multiples, often many dozens of turbines. So, a single reactor event may take a nuclear plant down for a month, or a single turbine issue may take a coal or gas plant down for a week. But a single wind turbine event, for even two days, is hardly a blip on the radar. Peter Wieck Melrose Park, PA |
| tabbypurr@gmail.com: Jul 10 06:04AM -0700 > Point being that a wind "farm" does not rely on a single turbine, but multiples, often many dozens of turbines. So, a single reactor event may take a nuclear plant down for a month, or a single turbine issue may take a coal or gas plant down for a week. But a single wind turbine event, for even two days, is hardly a blip on the radar. > Peter Wieck > Melrose Park, PA Reliability of course is not the key issue in comparing intermittent with controlled gen techs. It's been explained enough times, you don't get it. End of story. NT |
| Fox's Mercantile <jdangus@att.net>: Jul 10 08:20AM -0500 > Reliability of course is not the key issue in comparing > intermittent with controlled gen techs. It's been explained < enough times, you don't get it. End of story. > NT You remind me of my mother. I'd ask her a question, and if she didn't know the answer, she'd make something up. Then defend it to the death. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| tabbypurr@gmail.com: Jul 11 12:33PM -0700 On Wednesday, 10 July 2019 14:21:03 UTC+1, Fox's Mercantile wrote: > You remind me of my mother. > I'd ask her a question, and if she didn't know the answer, > she'd make something up. Then defend it to the death. You're an ignorant troll. Short term plonk. |
| Fox's Mercantile <jdangus@att.net>: Jul 11 03:27PM -0500 >> I'd ask her a question, and if she didn't know the answer, >> she'd make something up. Then defend it to the death. > You're an ignorant troll. Short term plonk. You just proved my point. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Phil Allison <pallison49@gmail.com>: Jul 11 03:44PM -0700 Fox's Mercantile wrote: > You remind me of my mother. > I'd ask her a question, and if she didn't know the answer, > she'd make something up. Then defend it to the death. ** Same goes for a great many folk, men and women. Their philosophy is that: "if it feels right, it is right" - a denial of the need for good evidence. Another famous saying pointing to the same fact is: "you cannot reason a person out of a position that reason never got them into in the first place". .... Phil |
| Bob Engelhardt <BobEngelhardt@comcast.net>: Jul 08 10:47AM -0400 If I measure a full wave voltage with a non true-RMS common variety DMM*, will it be off by a known factor, from the true RMS value? Or is there a rule of thumb about the error. E.g., the reading will be high by about 10%. Thanks, Bob * - Extech Ex320 if it matters |
| John Robertson <spam@flippers.com>: Jul 08 07:56AM -0700 On 2019/07/08 7:47 a.m., Bob Engelhardt wrote: > Thanks, > Bob > * - Extech Ex320 if it matters Typically these inexpensive digital meters are only fairly accurate for 60 or 50 Hz sine wave AC voltages. The further away from 50/60 Hz and/or true sine wave you get the worse the reading accuracy... Here is a good explanation: http://sound.whsites.net/appnotes/an012.htm I'd use a 'scope and do the math if the readings are critical and you can't afford a proper AC meter John :-#)# -- (Please post followups or tech inquiries to the USENET newsgroup) John's Jukes Ltd. MOVED to #7 - 3979 Marine Way, Burnaby, BC, Canada V5J 5E3 (604)872-5757 (Pinballs, Jukes, Video Games) www.flippers.com "Old pinballers never die, they just flip out." |
| Bob Engelhardt <BobEngelhardt@comcast.net>: Jul 08 01:16PM -0400 On 7/8/2019 10:56 AM, John Robertson wrote: >... > I'd use a 'scope and do the math if the readings are critical and you > can't afford a proper AC meter The readings aren't at all critical - a single-digit correction factor would be good enough. I wonder if the meter reading has a consistent relationship to the RMS value. E.g., if the meter always used the peak value, the actual value would simply be 0.7 the read value. If it was consistent, I could calculate the correction factor by measuring the peak on a scope. But I wouldn't want to have to generate correction curves. |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jul 08 01:24PM -0400 On 7/8/19 10:47 AM, Bob Engelhardt wrote: > Thanks, > Bob > * - Extech Ex320 if it matters Depends. If it reads the peaks, it'll be high by a factor of sqrt(2). If it reads the mean, it'll read 2/pi times the peak value, which is low by a factor 2*sqrt(2)/pi = 0.9003. So 10% is right in that case, except that it would read low. Of course it could do some random third thing instead. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| Look165 <look165@numericable.fr>: Jul 08 08:04PM +0200 I got a problem measuring efficienty on an SMPS unit. The meter I used was indicating about 50% which was absurd. I brought my personal old analog meter, it said about 85% ! That's why I don't like todays's meters. Bob Engelhardt a écrit le 08/07/2019 à 16:47 : |
| Phil Allison <pallison49@gmail.com>: Jul 08 02:23PM -0700 Bob Engelhardt wrote: ---------------------- > If I measure a full wave voltage ** I wish folk would use correct terminology and not private shorthand. Do you mean " full wave RECTIFIED voltage" or not ??? > with a non true-RMS common variety > DMM*, will it be off by a known factor, from the true RMS value? ** Standard DDMs take the average, AC coupled rectified value and scale to coincide with the rms value for sine waves For any other wave there is an inherent error and the DC component is missed with rectified waves etc. Try explaining what you are actually doing instead of being too clever. ..... Phil |
| Bob Engelhardt <BobEngelhardt@comcast.net>: Jul 08 05:30PM -0400 On 7/8/2019 5:23 PM, Phil Allison wrote: >> If I measure a full wave voltage > ** I wish folk would use correct terminology and not private shorthand. > Do you mean " full wave RECTIFIED voltage" or not ??? ... Sorry for the offense. I thought that it was obvious & didn't know that there was any other kind. What other kind of full wave is there, other than full wave rectified? |
| Bob Engelhardt <BobEngelhardt@comcast.net>: Jul 08 05:42PM -0400 Oh, wait ... the light dawns. The DC that I'm trying to measure is the output of a bridge. It's RMS value will just be the RMS value of the AC input, less 2 diode drops. Unless I'm missing something ... not unheard of. |
| Phil Allison <pallison49@gmail.com>: Jul 08 02:54PM -0700 Bob Engelhardt wrote: > ... > Sorry for the offense. I thought that it was obvious & didn't know that > there was any other kind. ** A full wave voltage is any continuous wave. Rectified waves are single polarity - big difference. .... Phil |
| Phil Allison <pallison49@gmail.com>: Jul 08 02:59PM -0700 Bob Engelhardt wrote: > The DC that I'm trying to measure is the > output of a bridge. It's RMS value will just be the RMS value of the AC > input, less 2 diode drops. Unless I'm missing something ... not unheard of. ** Now you are thinking well into the problem. The rms value is the equivalent heating effect of a wave expressed as a number. So, the addition of a bridge between an AC supply and it's load has little effect on the heat in that load except for losses in the bridge. Ergo, nearly the same rms value. .... Phil |
| Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net>: Jul 08 06:16PM -0400 On 7/8/19 2:04 PM, Look165 wrote: > The meter I used was indicating about 50% which was absurd. > I brought my personal old analog meter, it said about 85% ! > That's why I don't like todays's meters. You can get a true-RMS meter for way under $50. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com |
| Look165 <look165@numericable.fr>: Jul 09 11:02AM +0200 NO ; with today's DMM the value is only true with sine wave. Some use triangular signal, other Dirac comb. They sample the signal and then computation and mathematical process. The older one (AMM) were making true measurement with a rectifier and a filtering cap. This is particularly obvious in Amperemeter operations. Phil Hobbs a écrit le 09/07/2019 à 00:16 : |
| Look165 <look165@numericable.fr>: Jul 09 11:08AM +0200 Definition of RMS : The DC value that causes the same thermal effect on a resistor as the original signal. Phil Allison a écrit le 08/07/2019 à 23:59 : |
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