Lots of failing outdoor  LED lamps...very long overhead mains cable. - Page 1
Forum section: electronics / projects

author: ocset
author_rank: Super Contributor
timestamp: January 18, 2018, 09:15:21 pm
content: Hello,We have installed one hundred 25W outdoor LED lamps in a town in Bosnia. Sixty failed in just a few weeks.They all are fed from a single 240VAC generator which delivers power to the 2500 metres of mains cable. A contactor near the generator is used to switch them all on/off. The lamps are fitted every 25 metres along this cable. The cable is overhead (not buried). It’s aluminium cable. Its twisted, though the installers tell us that in places the twisting is “not so tight”. We suspect there is an awful lot of mains stray wiring inductance.The strange thing is that they have another run of one hundred of the exact same lamps, but in this case the 2500 metre mains cable is buried in the ground. –None of these lamps with the buried cable have failed despite being installed months ago.The lamps are controlled by microcontrollers in them which slowly dim the lamps as the night goes past the small hours, so as to save energy when few people are really outside.We suspect that maybe there is some kind of transmission line effect going on, with the long mains cable. We have advised the installers to fit an RC snubber across the contactor, and another across Live/neutral, just downstream of the contactor. We also wonder that with the “not so tightly twisted” mains cable, maybe noise is getting into the long overhead mains cable, and disrupting the microcontroller.The lamps are not SMPS based, but instead are sucessively switched linear current regulators. There is no mains input filter in each lamp, and the input stage is as in the attached. (ltspice sim also attached, including ZR431 model)May I request what are your thoughts on why they have failed?

author: Gyro
author_rank: Super Contributor
timestamp: January 18, 2018, 09:20:32 pm
content: Not another treez faulty LED lamp thread.

author: CopperCone
author_rank: Super Contributor
timestamp: January 18, 2018, 09:27:42 pm
content: a rival company could be using a injection transformer on the overhead lines to destroy them. Is living in Bosnia like grand theft auto?I wonder if a compulsator could be used for this purpose.Do you do failure analysis on these lights? That could tell you alot.

author: nfmax
author_rank: Super Contributor
timestamp: January 18, 2018, 09:38:20 pm
content: Lightning-induced transients?

author: Andy Watson
author_rank: Super Contributor
timestamp: January 18, 2018, 09:44:19 pm
content: Quote from: treez on January 18, 2018, 09:15:21 pmBut what evidence do you have?Why don't you install some mains monitoring equipment into one (or more) of the lamps. Until you have some data you're not going to know how to cure the problem. Essentially you're shooting in the dark.Can you rule out a faulty/sub-standard batch of components?QuoteAliens - for sure.

author: sleemanj
author_rank: Super Contributor
timestamp: January 18, 2018, 09:53:58 pm
content: You need to go and investigate in perwon, or at the VERY least get a failed example back for analysis, and photos of the installation. It sounds like all the information you have currently amounts to "light no work no more".Could be as simple as water ingress running down the overhead wires and not up from the underground ones.

author: Niklas
author_rank: Frequent Contributor
timestamp: January 18, 2018, 09:54:28 pm
content: There is no input filtering visible in the schematics. Is that true or is it just omitted?

author: dmills
author_rank: Super Contributor
timestamp: January 18, 2018, 10:02:42 pm
content: I thought these pieces of shit had a 22nF cap in them (Not shown in your spice model)?Get a power analyser out there (Fluke make the good stuff) and actually measure what happens, then you will be able to work out what is failing and more importantly why.2,500m is short for transmission line effects at the power frequency fundamental, but a arcing contractor could pump a lot of RF into the line and transmission line effects at ~300kHz (1/4 wave unterminated line) and 900kHz (3/4 wave line) are possible. Also, lightning produces large low frequency components, and an overhead line that long looks a lot like an aerial, but until you actually run a logger on the circuit it is all wild arsed guessing.In something like this it is very much worthwhile to spend whatever you have to to get some of the duds back to your lab (ideally together with information about where in the line they were and those power analyser logs).Regards, Dan.

author: james_s
author_rank: Super Contributor
timestamp: January 18, 2018, 10:19:25 pm
content: They're running off a generator? Have you tried a different generator? I've seen some that were not at all well regulated, and some produce a really nasty output. I've also seen strange interactions between certain types of LED drivers and a transformer product I was involved with. LED drivers particularly with active PFC had a strange interaction where the voltage out of the transformer was boosted up beyond 150V.

author: Kjelt
author_rank: Super Contributor
timestamp: January 18, 2018, 10:58:17 pm
content: Could be tons of reasons.Are your drivers potted, do they have Movs, sparkgaps and other protection?Can they survive brownouts, dips and peaks upto 277V ? No? Redesign your product.You can add something like this and see if it makes a differencehttp://www.lighting.philips.co.uk/oem-emea/products/xitanium_led_xtreme_drivers/philips-surge-protection-device

author: ocset
author_rank: Super Contributor
timestamp: January 19, 2018, 06:18:03 am
content: We are going to ask the installer to put small boxes across live/neutral. In these will be a series combo of TVS and 32mA quick blow fuse.The TVS will be SMCJ400CA.In another box we will have two series SMCJ250CA TVS's in series with a fuse. (this gives a bit higher voltage detection than a single SMCJ400CA)....If the fuse blows, then we at least know there was an overvoltage transientQuoteQuoteThanks , The 22n goes in the updated version. Not this version.QuoteThanks , Yes theres no input filter. We don’t need it, we aren’t using SMPS.QuoteThanks, do you think a lighting strike to one bit of the overhead cable would take out say 30 lamps either side of the strike point?.....i am guessing it would?

author: Jeroen3
author_rank: Super Contributor
timestamp: January 19, 2018, 08:01:36 am
content: Quote from: treez on January 19, 2018, 06:18:03 amThen what is going to protect your rectifiers?

author: Towger
author_rank: Super Contributor
timestamp: January 19, 2018, 08:33:33 am
content: It is not clear if the same generator is running both strings of lights?Did they fail after a thunder storm?The problem is you appear to be dealing with second hand information (Chinese Whispers), so you cannot fully trust the information.As others have said you need to get some back.Edit:A direct lightning strike would take out the lot and the generator. You do not need a strike when you have more than a few meters of wire in the air.

author: Wolfram
author_rank: Frequent Contributor
timestamp: January 19, 2018, 10:13:09 am
content: Has the design passed mains surge immunity testing to the applicable standards? Would your proposed "TVS + fast fuse" transient detectors survive such immunity testing?

author: Ice-Tea
author_rank: Super Contributor
timestamp: January 19, 2018, 11:02:29 am
content: Quote from: Wolfram on January 19, 2018, 10:13:09 am^|This.1) Test your device against surges from an applicable standard (K21 comes to mind)2) Use a datalogger to monitor the mains likehttp://www.fluke.com/fluke/uken/power-quality-tools/logging-power-meters/fluke-1740-series.htm?pid=56029Everything you are doing right now is guesswork.

author: tggzzz
author_rank: Super Contributor
timestamp: January 19, 2018, 11:35:32 am
content: Quote from: treez on January 18, 2018, 09:15:21 pmAre these the same failed lights that you have raised in your numerous other threads, or are they different failed lights? That information is important.In your previous threads you have always referred to assumed (but not verified) "problems" with the UK mains. This thread is about a completely different setup.Generators are very different to the UK mains supply, and are far less tightly regulated. For example, if you simply remove the load the output voltage will rise significantly until less fuel is fed to the motor.Ditto the "contactor" you mention; in the absence of contrary information you should assume it doesn't cleanly interrupt the current.

author: tggzzz
author_rank: Super Contributor
timestamp: January 19, 2018, 11:43:39 am
content: Quote from: treez on January 18, 2018, 09:15:21 pmThat should be easy to simulate in your spice model.Have a look atprofessionalequipment to see how such interference is prevented. The necessary components are in any of the big disties' catalogues.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 19, 2018, 12:00:21 pm
content: Quote from: treez on January 19, 2018, 06:18:03 amIf you had a strike to the cable you would know about it by looking at what, if anything, is left.A nearby strike could easily introduce a big transient though, as could things like flashovers on nearby HV power lines.Also things like nearby radio transmitters could induce significant voltages on the line.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 19, 2018, 12:03:01 pm
content: And of course you need to get hold of a couple of failed units for analysis as quickly as possible - as others have said it could be something as stupid as water ingress due to bad installation or case design.

author: Kalvin
author_rank: Super Contributor
timestamp: January 19, 2018, 12:15:22 pm
content: Where did you get the design in the first place? Any references to an application notes, existing reference designs, reverse-engineered existing products etc.?

author: floobydust
author_rank: Super Contributor
timestamp: January 19, 2018, 01:40:26 pm
content: AC generators are terrible and will make huge transients when switched in, and while running.I encounter very old, sluggish field-regulator designs that overshoot and glitch. They're pretty much best suited for running AC motors as a load, not electronics with PFC. The genset might have trouble regulating without some "normal" load present.Also check how the generator is earth-grounded, I've seen many 3-phase units that just float. It could be using the feeder wiring/LED lights as (capacitive) ground.You could check the (load) start-up sequence, if one LED string/feed is coming up before the other, it may be the sacrificial lamb getting the generator to settle.Transients can be very fast and surges very slow- using a clamp for transients, would quickly fail if it's the genset outputting a gross surge.These kind of problems are difficult to troubleshoot and I'd suggest renting a power analyzer, it will pay for itself.

author: Jeroen3
author_rank: Super Contributor
timestamp: January 19, 2018, 02:02:39 pm
content: It's only 2500 watts, so the generator is probably tiny as well. Meaning there can very well be severe distortion from the generator just being small.Think about triangle instead of since waves.

author: nfmax
author_rank: Super Contributor
timestamp: January 19, 2018, 02:32:11 pm
content: Quote from: mikeselectricstuff on January 19, 2018, 12:03:01 pmThat might fit: with overhead wiring the water runs down the cable, past the less-than-perfect cable gland, and into the luminaire. With underground wiring the cable (probably) enters the light from below, so water runsawayfrom the luminaire. This is why you need drip loops...

author: Zero999
author_rank: Super Contributor
timestamp: January 19, 2018, 03:19:25 pm
content: Quote from: treez on January 18, 2018, 09:15:21 pmYou do realise that you can't just model the cable with lumped components, such as resistors and capacitors?What components are failing?

author: floobydust
author_rank: Super Contributor
timestamp: January 19, 2018, 09:52:51 pm
content: yeah, 'fess up - what components are failing? Where are your autopsy results?

author: ocset
author_rank: Super Contributor
timestamp: January 19, 2018, 09:58:51 pm
content: Thanks, we are trying to arrange return of the units so we can see.QuoteThanks, well, yes, but…we have many installations in Holland and Germany, and overall thousands of products which see no failures for years….whole runs with no fails.QuoteThanks, I wonder how high it could have gone?QuoteThe rectifier is 1400v rated , and there is an LSP05 MOV module right at the front end of each lamp.I must admit I never really bought in to the idea that an AC filter comprising L’s and C’s really did much to reduce mains transients.QuoteThanks, no the underground cable fed lamps have a different generator to the overhead cable fed lamps…….they actually swapped the generator that had “served” on the overhead stretch during the failures….putting it on the underground stretch, and there were still no failures of underground cable fed lamps.QuoteThanks, we asked, and they specifically stated that they did not fail after thunder storms---------------------------------------------------------------------------The installers tell us that the failures occurred when there are lots of switching events - for example when they didn't have an earth return wire and were connecting Earth and Neutral at the actual earth ground at the pole base, there was lots of RCD tripping.--------------------------------------------------------------May i please ask what you thought of the TVS/fuse test jig to see if there are transients/overvoltage periods on the mains?..if the 32mA fuse blows then there absolutely must have been overvoltage...do you agree?

author: Andy Watson
author_rank: Super Contributor
timestamp: January 19, 2018, 10:25:47 pm
content: Quote from: treez on January 19, 2018, 09:58:51 pmAre you/they saying that stray ground currents have been deliberately introduced into neutral line at each lamp position?

author: tggzzz
author_rank: Super Contributor
timestamp: January 19, 2018, 11:49:07 pm
content: Quote from: treez on January 19, 2018, 09:58:51 pmCan you let us know whatformalelectronic engineering qualifications you possess.QuoteSo, you give us partial information and expect us to spend our lives trying to double-guess you. That is inconsiderate - and very unlikely to result in useful answers.

author: ocset
author_rank: Super Contributor
timestamp: January 20, 2018, 11:21:13 am
content: QuoteThanks, i think we all agree that there will be some attenuation of a mains voltage transient by an AC filter comprising L and C, but it is minimal, and thus we all use MOVs aswell as AC mains filtering ..and indeed, many offline SMPS's use 1200V rated FETs and input caps because they appreciate that the AC filter just isnt going to always be able to adequatley reduce all of the mains transients which hit it.QuoteI really dont think this is terribly relevant, ive met brilliant engineers who didnt have degrees.But since you ask, i have a First Class Honours BEng in Electronics from a very well known, Traditional UK university.I actually embarked on a degree in electronics thinking that if I worked at it, it would give knowledge which I could sell back to industry. I couldn’t have been more wrong.The UK electronics degrees are first and foremost, “Pre-PhD courses”……all the universities are interested in is those few brilliant students who are going to enhance the university's research activities as research students………the rest can go whistle.I am not complaining, with hindsite, universities have always been about producing and nurturing the worlds next brilliant pioneering scientists rather than about producing general engineers for industry –I should have known.On my course, many potential good engineers were wasted by the sheer academic-ness of the degree. There is also the fact that there is a big thing about attracting in foreign students (for their fees) , and being leaders in research , they believe, pulls in the foreigners.I can particularly remember one of our three second year maths lecturers.…His lectures were pathetic beyond belief.We would have to copy his notes from his horrendously messy scrawled projections….you could barely read them,…….you spent your entire time trying to decipher the mess…he would be rabbiting on at the same time, and it was simply impossible to copy his notes and try and decipher them, and listen to him aswell. I went on a post degree MSc at another uni in uk….and one of our lecturers would come in and literally read the notes to us word for word (the notes that he had given us)…in a very quiet monotonic voice…..then he’d get up and walk off.In truth less than 50 UK domiciled engineers qualify in UK every year with any kind of electronics qualification which involves electronics hardware as the main project subject.If you contact ONS, they will not tell you the number of UK domiciles qualifying in electronics each year in UK…they will just tell you the total number of foreign AND uk students who qualify..........................No Wonder Sir James Dyson has set up his own University for his students.

author: tggzzz
author_rank: Super Contributor
timestamp: January 20, 2018, 11:31:25 am
content: Quote from: treez on January 20, 2018, 11:21:13 amWhat should your lack of an answer to the question lead us to believe? EDIT: there is an answer, which seems to have passed this post in the aether.; hence this question is now moot.There are many bits of kit out there that are badly designed. Copying such equipment without understanding the consequences of their deficiencies is not a good starting point.One classic lack-of-understanding is based around the idea that "earth" or "ground" exists. They are merely convenient fictions that are useful in some circumstances - and dangerously misleading in others.

author: ocset
author_rank: Super Contributor
timestamp: January 20, 2018, 12:06:19 pm
content: QuoteThe following thread is good on Mains Transient protection, and confirms the fact that AC filters comprising L and C really aren’t much of a protection against mains voltage transient spikes. Yes they are significantly better than nothing though, agreed.http://www.edaboard.com/thread352771.html

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 20, 2018, 02:37:06 pm
content: Quote from: tggzzz on January 20, 2018, 11:31:25 amTrue but if you look at several PSUs for a similar market and they all have MOVs, it's a pretty good indication that they are seen to be necessary.@treez - did you do surge testing as part of compliance testing ?I'm not too familiar with the standards for CE marking in lighting, but ISTR EN61000-4-5 (surge) and EN61000-4-4 (fast transients) are both included in generic EMC immunity requirements.

author: nctnico
author_rank: Super Contributor
timestamp: January 20, 2018, 02:42:00 pm
content: Quote from: mikeselectricstuff on January 20, 2018, 02:37:06 pmAnd even then there will probably be differences between indoor and outdoor applications. One of my designs is an outdoor telecom device and it had to be tested with harsher tests compared to indoor devices.

author: BrianHG
author_rank: Super Contributor
timestamp: January 20, 2018, 02:47:13 pm
content: treez, once you get your failed outdoor units back, you might need to investigate these as a potential reason for your electronics blowing:a) Water infiltration into the electronics.b) Humidity build up in the electronics.c) Temperature sensitivity in the electronics.d) Thermal expansion/compressing due to daily temperature swings, even when off during the day, due to a poor circuit board design, or poor soldering.e) If your electronics are potted, that the potting's daily thermal expansion/contraction stress isn't creating a weak point for failure to occur.

author: tggzzz
author_rank: Super Contributor
timestamp: January 20, 2018, 03:07:12 pm
content: Quote from: mikeselectricstuff on January 20, 2018, 02:37:06 pmJust so. I was thinking more ofomittedcomponents, due to lack of understanding of the "unusual / non-standard" conditions where they are useful. Or, for that matter, cost-cutting such a Clive Sinclair employed.QuoteA sensible, basic question.

author: Kjelt
author_rank: Super Contributor
timestamp: January 20, 2018, 03:08:28 pm
content: I want to add that we europeans have a wrong look at mains variations. In my country there is about one mains outage per year and only local.In the US we did an installation and they told us they had an average of 50 to 100 outages per year, a nother one in the jungle was each and every day.Bosnia I don't know but before you sell or install a system rule nr1 is to find out exactly ehat you are up against and how hard it might be it is sometimes better to walk away from a deal.

author: ocset
author_rank: Super Contributor
timestamp: January 20, 2018, 05:20:01 pm
content: Thanks, is it possible for lighting to strike the ground near to outdoor streetlights, but not kill them..just "weaken them", so that they fail some weeks later?

author: Gyro
author_rank: Super Contributor
timestamp: January 20, 2018, 05:22:55 pm
content: The odd one... maybe, but 60? That's pushing credibility too far.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 20, 2018, 05:25:24 pm
content: Quote from: treez on January 20, 2018, 05:20:01 pmNot impossible but much more likely to kill straight away.Also possible a strike could have affected voltage regulation in the generator, but without evidence it's just guesswork

author: dmills
author_rank: Super Contributor
timestamp: January 20, 2018, 06:16:11 pm
content: Fluke power logger, also get the bloody things back and do some actual investigation, without that you (And we) are just guessing.The mains is all sorts of nasty (Especially when it might be 'mains' that is actually from a shonky generator intended to run builder power tools), but the nastiness is generally somewhat bounded and it is possible to design so you do not see many failures.You need to stop guessing at what the problem might be and use some tools to actually investigate. Your field failures are costing orders of magnitude more then the cost of hiring the appropriate tools (and if necessary expertise) and fixing the stupid things (To say nothing of what having a reliability record like that is doing to your chances of selling to a grown up customer, or even what it is doing to your own reputation).Regards, Dan.

author: IanB
author_rank: Super Contributor
timestamp: January 20, 2018, 06:42:12 pm
content: Quote from: treez on January 20, 2018, 11:21:13 amJust picking out this sentence from everything you wrote, you seem to have been under a major misapprehension. When you graduate with a freshly minted degree in engineering you become like an apprentice. You have gone through some basic training, and now you start on the learning curve. Industry has all the knowledge, and you don't. Your job is to start learning and soaking up the knowledge from all the more experienced engineers out there who have been there, done that, and who have learned in turn from their peers. The journey never ends, and every day there is something new to learn.

author: dmills
author_rank: Super Contributor
timestamp: January 20, 2018, 08:00:01 pm
content: Yep, every days a school day, and at least to some extent making mistakes is cool, it means you now know something that you did not know before, but you do have to seek to understand your mistakes.There are few things more useless in a design office then a newly minted graduate, especially if they cannot make good coffee! That is how it should be university is an ACADEMIC institution it is not a trade school, that graduate plus 10 years of industrial experience however sometimes turns into a very potent engineer.I would also note Treez that you have WAY more faith in spice then most around here do, it is reasonably good at telling you something is a non starter, but you need to be very good at modelling parasitic behaviour to be able to take a successful spice run and assume that it makes a design a goer.Regards, Dan.

author: tggzzz
author_rank: Super Contributor
timestamp: January 20, 2018, 08:48:13 pm
content: Quote from: IanB on January 20, 2018, 06:42:12 pmWell, yes - just so. TBH his whole message came across as a somewhat bitter diatribe, of the kind I've seen from people who haven't succeeded as well as they hoped and who have found someone else to blame. If that's the case then there isn't much that can be done, since "chips on shoulders" are never shifted by discussions.If I had to pick one sentence it would beQuote from: treez on January 20, 2018, 11:21:13 amWell, duh! That's the wholepointof a university degree. Agoodengineer will be able to see how the theory informs practice, and vice versa. If you want a more practical degree, go to one of the old Polytechnics.But I'd have to add anotherQuote from: treez on January 20, 2018, 11:21:13 amThat sounds like a good introduction to the real world: you have to learn how to deal with imperfect information sources of all kinds, and extract the subset of that information which you need.Besides, that'spreciselywhat 75% of my lecturers did! I rapidly evolved the technique of copying their scribbles on the OHP and then, within an hour or two, re-writing them in a decent form. That meant I really thoughtagainabout what they were teaching, and understood it much better (and/or asked them to clarify). It also made revision much easier.As for maths, a maths undergrad looked at our topics for out one maths course and commented "that's not far off what I'm learning in the entire year". At the end, the exam rubric said "full marks will be awarded for answers toaboutsix question"

author: ocset
author_rank: Super Contributor
timestamp: January 21, 2018, 03:58:15 pm
content: Quote…I could not agree more, and I had no such misapprehension. The thing is, in UK, there is little or no teaching of new grads by older engineers, because every older engineer in UK is scared of loosing their jobs, so the last thing they want is noobs coming through. Virtually the entire UK electronics industry is being sold off. Not only that, but few people graduate in electronics hardware in UK any more…less than 50 per year….https://massey276.wixsite.com/ukdeclineMost of the old electronics engineers in UK have given up electronics anyway due to the lack of jobs and prospects in UK now, and have gone into property management instead…..in UK now, a tiny terraced house inside the M25 will cost you a million pounds !!…Bag yourself a couple of these UK house bargains.....http://www.rightmove.co.uk/property-for-sale/property-61626499.html...notice that in 1996 it cost £72000Heres another dez rez....http://www.rightmove.co.uk/property-for-sale/property-50650614.html....cost you a million now...but was only 90 grand in year 2000http://www.rightmove.co.uk/property-for-sale/property-62418562.htmlnow £925000, but was a crisp £140000 in 1999http://www.rightmove.co.uk/property-for-sale/property-51265206.html…..i remember a very senior power guy had sheparded a PSU into G4 test trials, it failed, and instead of him being on hand to fix it, he had a few days off to fix failed boilers in his houses that he rented out to students.I have actually written a pretty full course in SMPS design and will email it to you via google drive if you send me your email by private mail on this site. That type of course is what should be given to undergrads…but the uni’s are not interested in making engineers for industry, they are solely interested in those few bods that are going to go into their research programmes. In UK now, the universities have “jean monnet professor-ships” etc, this is at best a waste of time, and more likely, totally un-patriotic and a sign of where UK universities are straying off.Also, i agree that a working sim means nothing. -But sims, i am sure you would agree, are a good way to help explain a cct concept to another.If you live in UK now, and you have any concern for it, then you should email this letter to your MP…https://massey276.wixsite.com/letterQuoteIn some ways yes, ...but in Germany, that sort of stink doesnt happen, and Germany reaps the benefits of their teamworkness, and in 2014, Germany was the worlds largest exporter by cpaital value. In Germany, retired engineers actually go into industry and colleges and freely give away their knowledge, at no cost.These engineers tell the noobs what to expect from industry........in UK, we never had one single working design engineer come and speak to us......managers yes, sales people yes, but no actual engineers.............i guess that kind of makes sense, why would a uk engineer go into a uk university and teach anybody anything when they would be speaking to an student audience of 95% non UK domiciles.

author: dmills
author_rank: Super Contributor
timestamp: January 21, 2018, 05:36:38 pm
content: Oh rot Treez, you need to lay off the good stuff, it is making you paranoid.Uni was never about prep for industry, and neither should it be, get thee to a poly or C&G course for that!Every senior engineer I know is quite willing to share design techniques, stories of expensive cockups and stories of how to manage the Ruperts in charge, it is the defining feature of the species.Most of them will quite happily help a junior with an unfamiliar problem or tool, it is after all in their interest, you want to have minions to deal with the component obsolescence issues and the boring toss like designing power supplies, programming micro-controllers and breaking out BGAs, so that you can have time to do the fun stuff, and the only way you get competent minions is by training them.Eventually the minions move on and get minions of their own, and so it goes.None of those guys are ending up unemployed any time soon, and a few I know have been trying to retire for most of the last 5 years...Regards, Dan

author: tggzzz
author_rank: Super Contributor
timestamp: January 21, 2018, 05:46:21 pm
content: Quote from: treez on January 21, 2018, 03:58:15 pm(Irrelevant diatribe about house prices omitted)Treez chose to obfuscate what he was saying by not including the context in which I made my statement - very annoying. I've re-inserted it above. Hint: please use the "quote" button; this isn't edaboard, and we can deal with extended conversations.Anyway, "knowledge elicitation" and "knowledge filtering" are just as important and difficult in Germany as they are here. And from personal knowledge and experience, I can assure you that the grass is still grass coloured on the other side of the fence. So you point about Germany is naive.Apart from that, you sound like you expect to be passively spoonfed with whatever you think you need both in university (course notes) and industry (people mentoring you). Well, sorry, life isn't like that and never has been; deal with it.Youare responsible for creating the opportunities you feel you are entitled to.In my experience,everybodyinallcompanies have beenmorethan willing to share their knowledge and experience, as am I. OTOH, some people are unconsciously irritating, particularly those that don't bother to askgood questionsas outlinedhere.Overall you come across as quite a difficult and needy person to have as a colleague, and one that will feel aggrieved if their "entitlement" doesn't materialise. Obviously I don't know if thatisthe case; it is based solely on what you have written here and elsewhere.

author: tggzzz
author_rank: Super Contributor
timestamp: January 21, 2018, 05:52:44 pm
content: Quote from: dmills on January 21, 2018, 05:36:38 pmYes, that all mirrors my experience.Rather than "good stuff", perhaps stress is the cause?

author: ocset
author_rank: Super Contributor
timestamp: January 21, 2018, 06:05:01 pm
content: QuoteThanks, "colleague"?.....does that mean other engineers?.......I ve been to a lot of companies in UK where they havent had an engineer in-house for a long time, in spite of desperately trying to recruit one......when you get there, you are the only engineering staff there. This is the state of UK today i mostly find. Its not unusual for UK companies to have payed some dodgy external contract engineer to do a contract for them, and its been a bad mess, didnt work, and they had no-one in house to sort it.You dont believe this then...https://massey276.wixsite.com/ukdecline

author: nctnico
author_rank: Super Contributor
timestamp: January 21, 2018, 06:31:05 pm
content: Back on-topic: get all the failed lamps and figure out how they failed. The fact of life for an electronics engineer is that sometimes it is hard to figure out why a circuit fails when installed at a customer.

author: Gyro
author_rank: Super Contributor
timestamp: January 21, 2018, 06:56:07 pm
content: Quote from: treez on January 21, 2018, 06:05:01 pmThat sounds like an error in your career path choice rather than an indictment of engineering in the UK. I don't know how long you are out of Uni, but picking companies where you are the only engineer early in your career is plain dumb, on both sides. You would be foolish for not looking for a mentoring environment and your employer is foolish for not seeking out a suitably experienced engineer (assuming any experienced engineer would fall for a company that wants to do everything on the cheap!*). Recruitment is a two sided process, assessing the employer is just as important (more so from your perspective) as assessing the candidate.Either way it sounds as if you need to get out of there while there is still time to save your career!Edit:*That's the real reason why they have had trouble recruiting, you've fallen into the trap.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2018, 07:05:07 pm
content: Quote from: mikeselectricstuff on January 20, 2018, 02:37:06 pmIn a couple other threads he's shown a toy he created for this. It delivers pissant pulses, with incorrect timing and polarity anyway. He believes it to be a valid test, despite being told otherwise numerous times here.Tim

author: Nusa
author_rank: Super Contributor
timestamp: January 21, 2018, 07:08:38 pm
content: Are the lights the sole load on the generator? I could see someone's chest freezer putting some lovely spikes on the line every time the motor starts.Is there a relationship between the failures and distance from the generator?

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 21, 2018, 09:59:21 pm
content: I have a new theory that treez is in fact a plant, placed deliberatly here to wind everybody up and create a disinformational climate.Could this indeed be related to the sources of fake news stories often talked about now. The continious postings over several months of sensational increadable theories could surely only come from a fake sourceMaybe we are being distracted from something we should really be looking at or the idea is to fry the brains of everybody on this site

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 21, 2018, 10:24:23 pm
content: Quote from: fourtytwo42 on January 21, 2018, 09:59:21 pmHeh, fancy, but unlikely. He's been around several forums for probably 10 years or more.His, erm, professional design methodology shall we say, has not evolved over the years.Tim

author: tggzzz
author_rank: Super Contributor
timestamp: January 21, 2018, 10:30:46 pm
content: Quote from: T3sl4co1l on January 21, 2018, 10:24:23 pmTen years? That surprises me, but is worth knowing.Mind you, your comments fit with my very tentative guesses. Shame

author: Cyberdragon
author_rank: Super Contributor
timestamp: January 22, 2018, 01:38:51 am
content: Quote from: fourtytwo42 on January 21, 2018, 09:59:21 pmOh...I think you meant that kind of...I was imagining an evil sentient ficus using a computer...

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 22, 2018, 05:53:55 am
content: Quote from: Cyberdragon on January 22, 2018, 01:38:51 amOn the internet, no one knows that you're a ...Tim

author: Siwastaja
author_rank: Super Contributor
timestamp: January 22, 2018, 06:28:22 am
content: Quote from: T3sl4co1l on January 21, 2018, 10:24:23 pmStress might be a contributing factor.When these LED fixture topics first started to appear, I thought: great, we have an honest engineer who designs with the help of this forum, we'll get a lots of great info from all the replies!We indeed have got some great technical posts (thank you Tim for being possibly the biggest contributor), but strangely, it doesn't seem to help the original poster go forward in their designs (or does so extremely slowly). (However, it has definitely helped others.)Actually I was cynical of other people being so cynical about their methodologies in the start. I mean, something in their methodology sounded familiar of how I work, and I find I've been succesful and have learned a lot - despite, and sometimes even thanks to low budgets and "unprofessional" settings (and making some treez-like mistakes that would have been avoidable with money and organization)!It's hard to understand why they are so stuck. treez seems to work hard, so we should start seeing some good results. This is why I'm suggesting stress: it narrows your mind, and you start focusing on just survival using the "nearest" methods available, even if they are unbeneficial in the long run (and disastrous to scientific thinking). Such methods include blaming UFOs etc.If he's the only actual engineer in the company, it tends to deepen the stressful situation, since you have no "peers" to vent your engineering stress (and actually think aboutengineeringsolutions). Instead, you have the management, and way too often, you need those sick "professional" social strategies with the management, including blame shifting. Too often, the management simply cannot accept this idea: "these things just fail sometimes due to human error, now we have to find the root cause, learn, and then we can avoid this mistake in the future!". Instead, the management corners you, forcing you to unconsciously defend the original mistake, which prevents you from learning. It takes a lot of self control to ignore confusion caused by the management and just go on the open-minded engineering/scientific way.

author: tggzzz
author_rank: Super Contributor
timestamp: January 22, 2018, 09:06:00 am
content: treez: you complain about the lack of engineering peers in your company, and the lack of mentoring.Have you considered joining the local branch of professional organisations, e.g. the IET. One of their raison d'etres is to provide mentoring, local support and networking.

author: dmills
author_rank: Super Contributor
timestamp: January 22, 2018, 09:32:41 am
content: Quote from: Cyberdragon on January 22, 2018, 01:38:51 am"Feed me Seymour!"

author: stj
author_rank: Super Contributor
timestamp: January 22, 2018, 12:26:50 pm
content: it's winter, are the zeners and reference rated down to negative temps??btw, i'm a not working u.k. engineer.i will explain the biggest problem - employment agency'smost company's insist on using them, but they are bandits.they dont care what the skillset of the person is - they just send people to places who cant really do the job.then take atleast half their wages and often commit tax fraud.result,engineers get robbed and sent to do jobs they arent suitable for,company's get the wrong people,slave traders get paid!!!personally i will *never* lift a finger for any company that insists on robbing it's workers via a slave agency.i wont even give them my name - you *know* the management arent giving 60% of earnings to a middleman and not having national insurance paid, or being asked to pay it twice!!so why should the real workers???

author: Kjelt
author_rank: Super Contributor
timestamp: January 22, 2018, 12:49:42 pm
content: Quote from: stj on January 22, 2018, 12:26:50 pmWell aren't all companies a kind of slave holders?They pay just enough to make your living and save a little bit, but too little so you can retire and quit after 20 years of hard work, thereby holding you ransom till they think you are old and retire you.Then the governments raises the pension age and almost nobody will ever see retirement from active duty.If you look at the amount of some jobs companies seek and can't find and fly in foreigners from India and further to get them here, those salaries should have quadruppled in the mean time, but they didn't.The salaries are relative to inflation the same as 15 years ago and lower than 30 years agoThe profit of those companies have doubled, tripled and more in some cases.Anyway back to reality, if you work even for an employment agency, you earn money which you do not if you do not work, so little choice there.Maybe we should think of ourselves as stakeholders in the company we work for. Then I always think of the Asterix & Obelix comic with the merchant captain hiring "stakeholders" in his enterprise and those stakeholders end up rowing the boat while the captain sits on his *ss

author: T3sl4co1l
author_rank: Super Contributor
timestamp: January 22, 2018, 05:44:37 pm
content: Quote from: Siwastaja on January 22, 2018, 06:28:22 amThat's a very good point.I learned long ago to take confidence in my work -- to the extent that I can, given that I make mistakes from time to time -- and that my situation is more like,That is, it's a bigger loss to them than to me if I left, and the only way I'm getting fired is if they simply don't need the engineering anymore.I'm never short of work; even if I run out of clients, I can develop my own projects, or take a salaried position at a half dozen companies in the area or abroad.I take confidence in my work, and only take clients who see and respect that work.This unfortunately isn't very helpful for someone of lesser skill -- if there's always someone ready to replace you, what good are you, at all? You've got to cover your ass and survive. Right?I don't have a good solution for that. It's a positive feedback system, you've got to break the loop somehow. Find employers who will support you, even in your bad decisions. An intolerant environment is no fun, period, no matter where you are. If nothing else, you should be safe for months or years at a time, contingent on performance or completion of a project, say.And hey, if the UK labor market is as tight as described, you must be doing something right by filling that demand. Maybe there aren't that many in line behind you, after all?Tim

author: chris_leyson
author_rank: Super Contributor
timestamp: January 22, 2018, 06:15:38 pm
content: QuoteI think your hunch might be right treez. Given that the line isn't "terminated" so to speak a transient or step at the generator end might give overvolts at the open end and then it's just up to the non-linear distributed load to absorb the transient voltage. Did most of the failures happen at the far end ?

author: nctnico
author_rank: Super Contributor
timestamp: January 22, 2018, 06:32:53 pm
content: Quote from: Siwastaja on January 22, 2018, 06:28:22 amYou have to realise not everyone is a brilliant engineer but some get quite far by just stapling & glueing bits and parts of other designs together. The problem is that engineers like these get totally lost when dealing with a complicated problem.

author: iwtommo
author_rank: Contributor
timestamp: January 22, 2018, 07:50:12 pm
content: Quote from: treez on January 19, 2018, 09:58:51 pmQuite high - 292v?

author: fourtytwo42
author_rank: Super Contributor
timestamp: January 22, 2018, 08:02:53 pm
content: Quote from: iwtommo on January 22, 2018, 07:50:12 pmThats become like 42, the ultimate answer to the ultimate question that was? (Hitchhikers guide to the galaxy anyone ?)Maybe there is another parralel here, deep thought (the mices computer) only knew the answer, not the question!!

author: Jeroen3
author_rank: Super Contributor
timestamp: January 22, 2018, 08:09:56 pm
content: Quote from: treez on January 19, 2018, 09:58:51 pm>60 Hz >500V (phase-phase) is not rare with a 100-0% load step. Most of the time it's something you can't fix with electronics either, it's just inertia and magnetics.Caterpillars are famous for this.

author: Towger
author_rank: Super Contributor
timestamp: January 22, 2018, 08:21:25 pm
content: Quote from: iwtommo on January 22, 2018, 07:50:12 pmQuite high - 292v?Depends on how crap the generator is :-)Don't forget these LEDs dimm to save power. What happens when the sun suddenly comes out from behind a cloud.A crap generator with no load...

author: stj
author_rank: Super Contributor
timestamp: January 22, 2018, 08:58:52 pm
content: larger generators are actually well regulated,they dont use the throttle, they use feedback to mess with the magnetic field in the generator with an extra coil.i'v worked on the big truck-mount ones.

author: nali
author_rank: Frequent Contributor
timestamp: January 22, 2018, 09:03:20 pm
content: Quote from: fourtytwo42 on January 22, 2018, 08:02:53 pmWasn't it 6 x 9 ?

author: Towger
author_rank: Super Contributor
timestamp: January 22, 2018, 10:12:11 pm
content: Quote from: stj on January 22, 2018, 08:58:52 pmSome of those are amazing. There was one powering 100+ houses in my housing estate (subdivision for the yanks) a while back, when the main power lines were being upgraded. I walked past it and and only realised is was running when I was hit in the face with a blast of hot air from it. It was whisper quiet.I suspect the OP's generator maybe more closely related to a Aldi/Lidl special.