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  1. #21
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    Quote Originally Posted by thermite View Post
    Lot of "lazy" in the wurld. Probably outnumbers stoopid? Why should power electronics be immune?
    Why should power electronics be immune if Boeing aircraft are not?
    Good to know you think me lazy, not reading the spec sheets and whatever else.
    I do not know it all and freely admit that I just offer advice from where I am.
    My SSRs used in the past will hit anywhere even at peak cycle. You have never seen this on the scope?

    Why would you poke at me this way? Am I making a big mistake in understanding SSRs?
    I have been doing controls for a few years but I do respect your background
    Bob

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    Quote Originally Posted by CarbideBob View Post
    Good to know you think me lazy, not reading the spec sheets and whatever else.
    I do not know it all and freely admit that I just offer advice from where I am.
    Bob
    Not YOU, Bob.

    Not unless you have changed careers?

    The guys who are PAID to get it right as THEIR "Day Job" ... then fail to do.

    Amateurs are amateurs..."Magic Smoke" would be DOOMED to perpetual slavery were it not for their valiant efforts at helping it escape!

    Heroes they are.. at least politically.

    Not so sure I'd want them working on my starship drive, though. I'm already picky about which aircraft I want under my ass at altitude. Not just brand. Model number.

    Midway, Chicago, August of 1968. Over-age-in-grade TWA Super-G Connie. Waaay overdue for takeoff whilst mechanics mess with numbah four..

    Pretty Lady finally comes over the tannoy with reassuring words apologizing for the delay:

    "Captain Anderson is trying to decide if the aircraft is safe to fly"

    Shuts the door, kicks those radials in the ass, climbs out on four, shuts down numbah four, fires her up again only as we approach PIT. In case he has to do a go-around. Shuts her down for taxi. Just in case the Mike Foxtrot catches fire. As usual.

    Have to tell yah.. after that? If it had pistons? Lycoming or Pratt & Whitney. NOT Continental or Wright.


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    Quote Originally Posted by thermite View Post

    Lot of "lazy" in the wurld. Probably outnumbers stoopid?

    Why should power electronics be immune if Boeing aircraft are not?
    I’ll be the first to admit I’m ignorant of many things, but I am curious and have a thirst to learn and explore and experiment, and I am far from lazy.

  5. #24
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    Just to spread a little sunshine on the differences between mechanical and solid state switches.

    For years in the USA the industrial standard for starters and contactors was NEMA. I don't have any idea when the standards were established, but for low voltage applications, up to 600 VAC, there were 9 standard sizes, 1-9. The various users were reviewed for the different applications to determine ratings. The most severe duty was a tapping machine where the motor was reversed constantly. This set the duty cycle. Then the type of switching was determined, making locked rotor, breaking running; making locked rotor breaking locked rotor, resistive heating, incandescent lighting and DC. These correspond to AC4, AC3 and AC1 in the european rating system. Equipment manufacturers and maintenance groups wanted one size to be able to cover all applications for a given motor size. That is, a size one starter could be applied on any application up to 10 hp (7.5 at the lower voltages) with thermal rating of 30 amps open or 27 amps enclosed. Because of this most NEMA contactors are waay over designed for most applications. This way a maintenance person could go to the tool crib, pickup a size one starter and know that regardless of the application it would work. Further JIC had additional requirements that the smallest starter to be used was a size one even if the motor was a 1/4 hp pump motor. The standards governing these are U/L 508, NEC 70, NEMA MG 1-2014.

    I have told but cannot verify that the reason for the IEC rating are because after WWll, material was scarce and could not be used willy nilly. A lot of application data was collected to allow the user to select just enough contactor for each application. This resulted in cost and size savings but now the user had to consult a lot of charts from each contactor manufacturer to select the the right device. Make a mistake and the contactor may not last. See IEC 158-1 standard.

    Solid state devices first started to appear in the 1950's but industrial devices were in the 1960's. By that I mean several hundred amps. Like the IEC, these devices cannot just be purchased and in hooked up, they need to selected according to the application. I am not an expert on these devices, perhaps Thermite will add some.

    Tom

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    Quote Originally Posted by TDegenhart View Post
    I am not an expert on these devices, perhaps Thermite will add some.
    The only thing I am "expert" on is finding information and paying closer attention to it than the average bear.

    So.. I pull the data sheets, dive-in, and by this late stage of reading before I could AFFORD. (family curse, just short of 100% retention as well..) actually understand them.

    As need dictates the choice, and THEN I always over-build, s**t I do tends to last.

    Much the same as those over-spec NEMA starters, my Hell box will have top-spec SSR's on both Voltage & current. That way, they are nearly always usable, even if overkill, when I need sumthin' in a hurry.

    So long as not blown-up, they have no "wearing" parts, so also re-usable, next project.

    All that said, I'm NOW digging-into Gigavac contactors - mechanical, but sealed - for another project.

    A replacement for the 10EE "DC panel" where several of the components have long-since gone unobtanium and not all that many of us - fewer still as are "young"- still know how to rebuild or fab.

  7. #26
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    Adding to TDegenhart's info...

    The basic difference between solid state things and mechanical ones, is the way they fail from heat..... They ALL basically fail from heat.

    SS ones fail from overcurrent that heats the chip up. That does not need to be that hot. There is a definite max current that will kill any given one, even just one pulse. A bit lower reduces life severely, lower just reduces life.

    The mechanical ones fail if you heat the contacts up enough to weld them. That's usually pretty hot, much hotter than the SS chip. And they take a while to heat that hot, yes, serious overcurrents that do not reach the welding point can make them degrade, transfer material, etc. But it takes longer, not usually just once unless it is truly stupid, in which case the SS part would have evaporated. Generally the same degradation takes much more current, and/or longer current.

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    Quote Originally Posted by JST View Post
    Adding to TDegenhart's info...

    The basic difference between solid state things and mechanical ones, is the way they fail from heat..... They ALL basically fail from heat.

    SS ones fail from overcurrent that heats the chip up. That does not need to be that hot. There is a definite max current that will kill any given one, even just one pulse. A bit lower reduces life severely, lower just reduces life.

    The mechanical ones fail if you heat the contacts up enough to weld them. That's usually pretty hot, much hotter than the SS chip. And they take a while to heat that hot, yes, serious overcurrents that do not reach the welding point can make them degrade, transfer material, etc. But it takes longer, not usually just once unless it is truly stupid, in which case the SS part would have evaporated. Generally the same degradation takes much more current, and/or longer current.
    Ummh.. seems to me that's why each tribe produces more than one rated capacity?

    I mean a 2400 Amp SSR just might stand more current than a 300 Amp mechanical?

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    What I was trying to point out is that with NEMA motor starters, they are simple to choose and apply and they work. They will take a lot of abuse and keep on trucking.

    Not so with IEC starters.

    As far as I know there are no solid state starters equivalent to NEMA starters, the closest I would say are VFD's but they have their issues. They are not bulletproof like mechanical starters. They do have advantages over mechanical starters in that they have built in OL protection, soft start and don't need a second starter to make a reverser. But as with all ssr's need a backup mechanical isolation switch, cooling and protection from line transients. Some applications don't work well with the high frequency switched power.

    Tom

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    Quote Originally Posted by TDegenhart View Post
    What I was trying to point out is that with NEMA motor starters, they are simple to choose and apply and they work. They will take a lot of abuse and keep on trucking.
    The one thing that they don't tell is the number of cycles. The little dinky new versions today do not last like their parents.

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    Quote Originally Posted by rons View Post
    The one thing that they don't tell is the number of cycles. The little dinky new versions today do not last like their parents.
    There hasn't been a new NEMA design starter from any of the manufacturers since the the 1990's. Most were from the 1970's - 1980's. Every product now is to the IEC design. In some cases US starters are simply brand labels of off shore products. The US had a second class of starters for years for those that didn't need all the NEMA performance. They are called DP's for definite purpose. In some cases these were NEMA designs that were relabeled with higher ratings, others were specific designs. These were to service limited performance need price sensitive markets like air conditioning and small hobby or light industrial grade machines.

    Tom

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    Quote Originally Posted by TDegenhart View Post
    What I was trying to point out is that with NEMA motor starters, they are simple to choose and apply and they work. They will take a lot of abuse and keep on trucking.

    Not so with IEC starters.

    As far as I know there are no solid state starters equivalent to NEMA starters, the closest I would say are VFD's but they have their issues. They are not bulletproof like mechanical starters. They do have advantages over mechanical starters in that they have built in OL protection, soft start and don't need a second starter to make a reverser. But as with all ssr's need a backup mechanical isolation switch, cooling and protection from line transients. Some applications don't work well with the high frequency switched power.

    Tom
    You are speaking as an experienced hand, with broad general experience, but something of a specialist, even so.

    I'm coming at it from never having had to problem-solve or do original design to the same task even TWICE.

    Which means I have HAD TO do more research. First time. Every time.

    No choice in the matter. After the first half-century, plus? One is aware there WILL be lots more successful solutions than just the ones yah already know about, be they few or many.

    Example: Low-priority project I just fired-off, "procrastination" my "real name" or otherwise, a workalike DC panel for universal MG, WiaD, module drive 10EE. All the existing stuff has worked well for nearly 80 years, just in the 10EE, and perhaps 40 years before that on Ward-Leonard system DC powered elevators and hoists.

    It has also, by this late stage in a new century, gone too hard to find.

    SSR's for the DC Contactors?

    Nossir.

    Researching the NEGATIVES to Gigavac HX22's. Mechanicals, but newer tech, and "sealed". Basis for another hundred-year no, low maintenance panel? Probably not. But that's the goal, and "close" will be good enuf'.

    The positives are easy. Maker's cannot HELP but tell yah THOSE lies. That's their rice-bowl.

    That's also why we have to do the research....


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    So are Gigavac's vacuum switches? I couldn't find a description of how they work. Do they have the mechanical life limitations of the older vacuum's as in the bellows. How do you get around the current chopping. The older designs for use with inductors had a special allow for the contacts to allow limited arcing which of course caused problems. Are they magnetic or air pressure. Do they have a quenching system such as SF6? What do they cost and what current/voltage rating as available?

    Tom

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    Quote Originally Posted by TDegenhart View Post
    So are Gigavac's vacuum switches? I couldn't find a description of how they work. Do they have the mechanical life limitations of the older vacuum's as in the bellows. How do you get around the current chopping. The older designs for use with inductors had a special allow for the contacts to allow limited arcing which of course caused problems. Are they magnetic or air pressure. Do they have a quenching system such as SF6? What do they cost and what current/voltage rating as available?

    Tom
    Tom.. I said I do a LOT of research.

    But I'd be wrong to get in the way of any other Pilgrim doing HIS OWN research.

    Your pre-conceptions or starting point or points will not be the same. Your goals will not be the same.

    GIGAVAC Company Overview

    I am certain they have competition. I shall be looking for it.

    My "preliminary" take is 1,000 Volt and 300A "working" ratings, failure points higher-yet, nominally / probably explosion-proof or near-as-dammit, protected against getting easily rectumfried, not position-sensitive as Hg displacement are..

    High Voltage Contactors - HX Series

    About US$ 130 each, two needed.

    Biggest downside already obvious is that they are manufactured in a high-risk Socialist zone that has a dodgy future. Two of them, perhaps. They WERE being made in China. What could be worse?

    The Kalifornikyah SSR.

    More likely, yet to run out of money, water, power, or air cool enough to support life at any time, leave the factory and/or skilled staff GONE and the product orphaned. Or back to Chinese made?

    Goal is long life. It's what 10EE "do". So that "supply chain reliability" or lack-thereof is part of my type of research. That has ALWAYS served my employers or clients better than tech-specs alone, so I'm sticking with it.

    This is cannot be a wise design "win" with that combination, any more than if they were a Russian or Nigerian factory, goods made for a Ukrainian-managed firm in the Donbass.

    Some other Pilgrim can do cheap .. or quick and dirty.


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    Quote Originally Posted by thermite View Post
    Ummh.. seems to me that's why each tribe produces more than one rated capacity?

    I mean a 2400 Amp SSR just might stand more current than a 300 Amp mechanical?

    Yippur..... them is tougher than the little ones.

    But these things are made to prices, and sizes, etc. The big stuff costs more. So does the stuff to drive it.

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    From what I have been to discern, Gigavac's are DC only. Good application for EV's, mechanicals don't do well on high voltage dc.

    Tom

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    Quote Originally Posted by rons View Post
    The one thing that they don't tell is the number of cycles. The little dinky new versions today do not last like their parents.
    How many cycles do you need, mechanical and electrical. What type of electrical, m/b LR, make lr, break running, resistive, There were no standards for life in NEMA, IEC pubs do have life as a function of switching. DP's were 500000 mechanical, electrical 100,000 AC3.

    Tom

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    Quote Originally Posted by TDegenhart View Post
    How many cycles do you need, mechanical and electrical. What type of electrical, m/b LR, make lr, break running, resistive, There were no standards for life in NEMA, IEC pubs do have life as a function of switching. DP's were 500000 mechanical, electrical 100,000 AC3.

    Tom
    ..and TTY reed relays were into the multiple millions.

    Which isn't as long as it sounds, wall-clock time, when yah were moving data, 24-7-365, not just setting up a voice call and tearing it down several minutes later.

    Horses for courses.

    Just for shits and giggles, look up the space a stock SKU numbah solid-state DC Drive for DC motors in the 9,000 and 14,000 horsepower range needs for parking its gawdawful-costly arse.

    ABB & sputniks may publish those in their "Products" range lineup, but ga-ron-tee delivery is a major negotiated "project", not just an ignorant online "shopping cart" box-tick and fast PayPal checkout!


  20. #38
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    You design for the needs of the application. I have been in central offices with strogers switches and to be quite honest I have never seen a relay or selector switch that has worn out. As is stated, those switches are on the go constantly and with VERY few failures. Millions and millions of cycles. I don't even know what the wear out mechanism is.

    On the other hand a size 5 contactor with a mechanical life of 1 million is probably unneeded. If you need more than that, that's when it's time for the solid state starters. And yes, I have seen size 5's on resistive heating applications where that type of life is needed. At the conclusion of my work on the GE size 1, CR305, I was able to get 10 million mechanical cycles from it and it was still going. Other than good mechanical design and manufacture was a few drops of perfluorinated polyether (Krytox) on the magnets. Secrets of the trade.

    Tom

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    Quote Originally Posted by TDegenhart View Post
    You design for the needs of the application. I have been in central offices with strogers switches and to be quite honest I have never seen a relay or selector switch that has worn out. As is stated, those switches are on the go constantly and with VERY few failures. Millions and millions of cycles. I don't even know what the wear out mechanism is.
    The "mechanism" is prevention. "Routine-ing". Usually part of a training program and politico/economic-driven.

    The one where the dominant-carrier telcos of the world shipped old SXS rigs to at-the-time "third word" countries a-purpose,"back in the day".

    It wasn't to dis-advantage them. Quite the reverse.

    What it did that modern TDM or packet rigs as could do a whole Island, African, Asian, or Latam country out of a rack or three could NOT do was provide JOBS.

    JOBS for bright young folks who had no other future were how C&W and others clinched our "exclusive" licenses with the ruling politicians. Politicians ALWAYS score points off providing jobs, as that spills-over to whole families.

    Those "bright young folks" learned the simple stuff. Reconditioning the crickets. FROM that pool, we could then recruit and send the best ones off to learn NEW technology. All of that C&W paid-for. Travel to Porthcurno or Warwick, wages, lodging, and all. Low risk for either party. Some of those folks became top Engineers, Managers, even Directors and CEO's of entire national telecoms firms.

    And not only telecoms.

    Thank you, Almon B. Strowger.

    You wrought better, wider, deeper, and longer goodness than ever you could have imagined.


    On the other hand a size 5 contactor with a mechanical life of 1 million is probably unneeded. If you need more than that, that's when it's time for the solid state starters. And yes, I have seen size 5's on resistive heating applications where that type of life is needed. At the conclusion of my work on the GE size 1, CR305, I was able to get 10 million mechanical cycles from it and it was still going. Other than good mechanical design and manufacture was a few drops of perfluorinated polyether (Krytox) on the magnets. Secrets of the trade.

    Tom
    "Secrets" of MY trade was finding good people, motivating them, then getting the f**k out of their way.

    Dunno WHY it is, but "ULM" seems to find that last part the hardest.

    Guess you have to be LAZY as well as leadershipish?

    Lazy, I surely am.


  22. #40
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    Reversing, particularly if it will get "plugged" is much different than just turning something on and off.

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