| Larz <dispcal667@nospam.net>: Sep 22 02:30PM -0400 I recently installed a mercury vapor light fixture. It is a 125 W lamp with integrated ballast in the housing. Today, I check the current with a clamp ammeter on the 120 VAC/ 60 Hz line going into the housing. After a 10 minute warm up, the current reads approximately 2.3 A AC. Not being sure, I then wired a series multimeter in line for a moment and it too read 2.3 A. Unfortunately, there is no PFC with this yard light, only the bulb and ballast, so I don't think anything can be done. However.... In another set up I have on the way, there is the 175 W MV bulb, ballast and the PFC capacitor that will be used with the ballast. Any ideas as to performance would be welcome. I'm just looking for in general as I realize we can't get too specific without any more figures, but I'm really hoping the efficiency is better than with the 125 W set up. Thank you in advance. |
| Larz <dispcal667@nospam.net>: Sep 22 02:50PM -0400 On 9/22/19 2:42 PM, KenW wrote: > Since I have no idea about them I searched for > PFC capacitor < > and there is plenty of information about them which my help you. > KenW I was just hoping to cut to the chase with someone using the examples above. I'm not all that pleased with the lack of efficiency with the 125 W lamp, just wondering if the capacitor would increase efficiency with the 175 W set up. At one time, 25+ years ago, in college, we actually had to calculate the correct capacitor to use in a circuit for PFC, but that's the last time I did it. |
| Larz <dispcal667@nospam.net>: Sep 22 03:02PM -0400 On 9/22/19 2:42 PM, KenW wrote: > Since I have no idea about them I searched for > PFC capacitor < > and there is plenty of information about them which my help you. > KenW Ok, this shows me what happens: https://www.youtube.com/watch?v=dPFKcUxbNuQ Great refresher! So the capacitor in the mercury vapor circuit should reduce the current if matched correctly. I wonder why there is no such capacitor in my 125 W mercury vapor yard light? |
| Phil Allison <pallison49@gmail.com>: Sep 22 08:05PM -0700 Larz wrote: ------------ > to performance would be welcome. I'm just looking for in general as I > realize we can't get too specific without any more figures, but I'm > really hoping the efficiency is better than with the 125 W set up. ** You are working under a serious delusion. PFC caps or circuits have *NO* effect on a device's efficiency. Power consumption remains exactly the same, with or without. The sole purpose is to reduce the *current draw* and allow more lights or whatever to be used on the same AC supply circuit. Current draw that is non-sine wave or not in phase with the voltage is always higher than when it is. ..... Phil |
| Rob <nomail@example.com>: Sep 23 08:46AM > Great refresher! So the capacitor in the mercury vapor circuit should > reduce the current if matched correctly. I wonder why there is no such > capacitor in my 125 W mercury vapor yard light? Because it does not really matter for lamps that are typically used solitarily or with 2 or 3. It is of course different when hundreds of streetlights have to be powered. |
| tabbypurr@gmail.com: Sep 23 02:27AM -0700 On Sunday, 22 September 2019 19:30:46 UTC+1, Larz wrote: > and it too read 2.3 A. Unfortunately, there is no PFC with this yard > light, only the bulb and ballast, so I don't think anything can be done. > However.... done about what? PFC is normally immaterial in domestic discharge lamps. You're not paying for the reactive current. > In another set up I have on the way, there is the 175 W MV bulb, ballast > and the PFC capacitor that will be used with the ballast. Any ideas as > to performance would be welcome. google mercury lamps to get the figures. They're poor compared to fluorescent, led, sodium or more modern discharge lamps, hence they're obsolete. > realize we can't get too specific without any more figures, but I'm > really hoping the efficiency is better than with the 125 W set up. > Thank you in advance. higher power discharge lamps do tend to be more efficient, but you're stuck with a poor efficiency lamp. Unless you change the lamp for something compatible & a lot more modern. NT |
| Cursitor Doom <curd@notformail.com>: Sep 23 01:30PM On Sun, 22 Sep 2019 15:02:07 -0400, Larz wrote: > Great refresher! Obviously not *that* great. > So the capacitor in the mercury vapor circuit should > reduce the current if matched correctly. I wonder why there is no such > capacitor in my 125 W mercury vapor yard light? Oh dear oh dear. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
| "pfjw@aol.com" <peterwieck33@gmail.com>: Sep 23 06:43AM -0700 Larz is amongst the Invincibly Ignorant - reminds me of Jimmy Neutron it its own way - might even be the same creature. Let it be. Peter Wieck Melrose Park, PA |
| Adrian Caspersz <email@here.invalid>: Sep 23 04:25PM +0100 > Larz is amongst the Invincibly Ignorant - reminds me of Jimmy Neutron it its own way - might even be the same creature. > Let it be. Wait till it starts posting lots of links and answers its own questions. Then you have id :-) -- Adrian C |
| Fox's Mercantile <jdangus@att.net>: Sep 23 11:03AM -0500 On 9/23/19 10:25 AM, Adrian Caspersz wrote: >> Let it be. > Wait till it starts posting lots of links and answers its own questions. > Then you have id :-) *Laughs* You're thinking of that carbuncle on the ass of humanity Arlen Holder. -- "I am a river to my people." Jeff-1.0 WA6FWi http:foxsmercantile.com |
| Adrian Caspersz <email@here.invalid>: Sep 22 07:22PM +0100 On 22/09/2019 11:46, Cursitor Doom wrote: > is/are the most likely suspects to be considered blameworthy? I'm > guessing dry joints has to be on the list somewhere, but what components > can also give rise to this issue? Not much to go on. Age of board? What does it do? Digital? Old caps can go leaky losing capacitance with temperature. If they were decoupling something from interference ... I'd scope out the power supply rails with a DSO, maybe you might catch something. Can you arrange a trigger when the fault occurs? -- Adrian C |
| John Robertson <spam@flippers.com>: Sep 22 01:14PM -0700 On 2019/09/22 4:48 a.m., Cursitor Doom wrote: > case it's not possible as the board in question is one of these slot-in > types that are inaccessible to investigation when the instrument is under > power. :( Lets assume you have the schematics and a bench/lab power supply and you know what goes wrong when the board is warm. Then why not put the board on the bench powered up by your power supply and check the parameters of the circuit whose change can lead to the symptom you see? Check the voltages when just turned on, then heat it up and see what changes. You don't need an extension card, although they are very handy - I have a dozen or so - however if the card connections are more-or-less standard you can make your own using a plug (hacked from a dead PCB perhaps) and socket and some wire. These will usually work, just usually aren't very good at 100khz or higher frequencies... It all depends on how badly you want to fix this and what your skills are... John :-#)# |
| Cursitor Doom <curd@notformail.com>: Sep 22 08:54PM On Sun, 22 Sep 2019 19:22:20 +0100, Adrian Caspersz wrote: > Not much to go on. > Age of board? What does it do? Digital? 30 years; CRT horizontal sweep amplifier; 100% analogue. > Old caps can go leaky losing capacitance with temperature. If they were > decoupling something from interference ... Quite. > I'd scope out the power supply rails with a DSO, maybe you might catch > something. Precisely what I am about to do next! > Can you arrange a trigger when the fault occurs? It's now so recurrent that no special triggering is needed. At the pre- driver stage (the output from the sweep gen stage) I see a nice clean saw- tooth waveform but 3 stages later I see the same trace; same amplitude but frizzled by severe noise and twitching like mad. So I'm closing in on it but am hampered by the fact that the board is inaccessible when powered up since it sits in a slot alongside other boards. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
| tabbypurr@gmail.com: Sep 23 02:22AM -0700 On Sunday, 22 September 2019 21:54:10 UTC+1, Cursitor Doom wrote: > but frizzled by severe noise and twitching like mad. So I'm closing in on > it but am hampered by the fact that the board is inaccessible when > powered up since it sits in a slot alongside other boards. Tack on a bunch of wires to points you'd like to scope. Install board, scope those points, move on. It sounds like you're very close to finding the culprit. NT |
| Cursitor Doom <curd@notformail.com>: Sep 23 01:35PM On Mon, 23 Sep 2019 02:22:44 -0700, tabbypurr wrote: > Tack on a bunch of wires to points you'd like to scope. Install board, > scope those points, move on. Yup, in fact that's what I had to do to find the excessive noise I mentioned in an earlier post. I hadn't expected to find it; I wasn't looking for noise, but I couldn't very well ignore it given it represented about 50% of the waveform amplitude! > It sounds like you're very close to finding > the culprit. Hopefully. But this unit has multiple issues and this is just one of them. Fortunately for me this is just for fun. If I had to do this for a living I wouldn't survive very long due to the time I take over these things it simply wouldn't be economic. Anyway, time now to get on and scope those power rails.... -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition. |
| KenW <ken1943@invalid.net>: Sep 22 12:42PM -0600 On Sun, 22 Sep 2019 14:30:42 -0400, Larz <dispcal667@nospam.net> wrote: >realize we can't get too specific without any more figures, but I'm >really hoping the efficiency is better than with the 125 W set up. >Thank you in advance. Since I have no idea about them I searched for > PFC capacitor < and there is plenty of information about them which my help you. KenW |
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