Lots of failing outdoor LED lamps...very long overhead mains cable.

[ocset]

Thanks, we are trying to arrange return of the units so we can see.

Are these the same failed lights that you have raised in your numerous other threads, or are they different failed lights? That information is important.

Thanks, 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.

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.

Thanks, I wonder how high it could have gone?

Then what is going to protect your rectifiers?

The 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.

It is not clear if the same generator is running both strings of lights?

Thanks, 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.

Did they fail after a thunder storm?

Thanks, 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?

[Andy Watson]

- 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,

Are you/they saying that stray ground currents have been deliberately introduced into neutral line at each lamp position?

[tggzzz]

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.

Can you let us know what formal electronic engineering qualifications you possess.

---------------------------------------------------------------------------
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.
--------------------------------------------------------------

So, 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.

[ocset]

    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.
Can you let us know what formal electronic engineering qualifications you possess.

Thanks, 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.

Can you let us know what formal electronic engineering qualifications you possess.

I 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. 

[tggzzz]

    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.
Can you let us know what formal electronic engineering qualifications you possess.

Thanks, 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 reduce  all of the mains transients which hit it.

What 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.

[ocset]

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.

Can you let us know what formal electronic engineering qualifications you possess.
 

The 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

[mikeselectricstuff]

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.

True 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. 

[nctnico]

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.

True 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.

And 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.

[BrianHG]

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.

[tggzzz]

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.

True 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.

Just so. I was thinking more of omitted components, 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.

@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.

A sensible, basic question.

[Kjelt]

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.

[ocset]

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?

[Gyro]

The odd one... maybe, but 60? That's pushing credibility too far.

[mikeselectricstuff]

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?

Not 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

[dmills]

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.

[IanB]

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.

Just 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.

[dmills]

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.

[tggzzz]

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.

Just 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.

Well, 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 be

On my course, many potential good engineers were wasted by the sheer academic-ness of the degree.

Well, duh! That's the whole point of a university degree. A good engineer 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 another

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.

That 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's precisely what 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 thought again about 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 to about six question"

[ocset]

Just 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.

…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/ukdecline

Most 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 £72000

Heres 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 2000

http://www.rightmove.co.uk/property-for-sale/property-62418562.html
now £925000, but was a crisp £140000 in 1999

http://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/letter

That 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.

In 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.

[dmills]

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

[tggzzz]

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.

That 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.

In 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.

(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. You are responsible for creating the opportunities you feel you are entitled to.

In my experience, everybody in all companies have been more than willing to share their knowledge and experience, as am I. OTOH, some people are unconsciously irritating, particularly those that don't bother to ask good questions as outlined here.

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 that is the case; it is based solely on what you have written here and elsewhere.

[tggzzz]

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... 

Yes, that all mirrors my experience.

Rather than "good stuff", perhaps stress is the cause?

[ocset]

Overall you come across as quite a difficult and needy person to have as a colleague

Thanks, "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

[nctnico]

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.

[Gyro]

Overall you come across as quite a difficult and needy person to have as a colleague

Thanks, "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

That 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.