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multiple SS in series...

Discussion in 'Hardware' started by technaught, May 15, 2006.

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  1. technaught

    technaught Banned Thread Starter

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    We just had another thunderstorm here. I couldn't turn on the PC when I got home 'cuz of
    it. My pc, like me, is allergic to voltage spikes. I develop severe allergic reactions to hi voltage/amperage.

    I have a half a dozen of the $5 surge suppressors layin' around here. I've seen some that go for $205, with protection guarantee, and am wonderin' if the $5 SS'ers, plugged in, IN SERIES, will give the same degree of protection??? :confused:
     
  2. qldit

    qldit

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    Good Evening technaught, generally with surge arresters you get what you pay for.
    Most often they contain a special voltage dependent resistor device which conducts once a specific voltage is reached, which is probably something in the order of twice your normal mains voltage.
    Hopefully the household device can handle that period of rising transient level without self destructing.
    Remember that these things when fitted to power leads or power boards only conduct excess levels back to the earth system and very often actually get vapourised themselves.
    So as a protective device they have a level of protection maybe.

    The larger types often are mounted in the mains power switchboard and have a better operation envelope, usually with better current capability. Some even have gas filled gadgets in them.

    Of course you could use a lightning deterrent system where radioactive gadgets on poles negatively ionise the air to reduce the leader potential.

    In the case of a reasonable strike on your home or the power pole out front, you really can't expect much protection because of the amplitude.

    The best protective method is to remove power plugs from sockets and isolate gadgets whenever lightning activity is present.
    At this location we have odd violent summer electrical storms, low cloud cover as low as 800 feet, simple ground strikes, as many as 1000 per hour in a twenty kilometer square.
    So you learn to live with it. These storms here usually pass in thirty or so minutes.

    If we want to keep sensitive equipment we have a plug out routine, especially with antennae.
    Some special power supplies can provide filtered controlled AC but again you get what you pay for.

    The most common idea is to insure all your devices against fire, theft, and make especially sure a reasonable lightning cover is included.
    Most people gamble that their items will survive so don't act to avoid problems.

    One such fellow was working on his computer during one of these storms, a loud bang happened and the lights went out, as this happened a smoking thing bounced across the floor near him, on investigation he found it to be the glass housing of the screen in his now demolished video recorder.
    The damage in that home was substantial, every TV, clocks, stove, washing machine microwave, garage door mechanism, aircon, a couple of computers, video player etc.
    Probably the only things that still worked were the lights that hadn't been switched on.
    It was likely the external TV antenna had been hit.
    A surge protector probably would not have been much protection in that case.

    I would imagine your machine wouldn't have been turned on but the system is still powered and would still be affected.
    Very often these kinds of instances result in the power supply being destructed, primarily because it is a switchmode system and the solid state devices fail before the time constants in the output voltage rails is achieved, but oddly enough you may well find that your hard drive has also been affected.
    More often the other components seem to escape damage. Strange!

    Your mention of allergies to electrical activity is interesting, as you probably know the cloud base is incredible negative. (the top of the cloud is incredibly positive)
    There is a ground element which rises from the ground to establish the leader, this jagged component rises up to about 6 metres from the ground and produces substantial charged particles, essentially ozone, many people are substantially affected by this charged effect and actually suffer severe asthmatic events.
    More often this is a long term asthmatic type person and it is really accentuated when a major electrical storm happens, you would be aware there is also a psycho element involved. (LOL)

    Commisserations. qldit.
     
  3. JohnWill

    JohnWill Retired Moderator

    Joined:
    Oct 19, 2002
    Messages:
    106,418
    MOV's, the protection component in virtually all cheap surge protectors, have a limited life. Here's a site where you can read about transient protection. http://www.transysprotection.com/
     
  4. technaught

    technaught Banned Thread Starter

    Joined:
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    Good stuff, gldit. Not your first day, I presume.

    An odd question or two, if you'll indulge...

    EDIT: Oops! Reply didn't format correctly gld..

    How about amperage? [/QUOTE]
    Hopefully the household device can handle that period of rising transient level without self destructing.
    Remember that these things when fitted to power leads or power boards only conduct excess levels back to the earth system and very often actually get vapourised themselves.
    So as a protective device they have a level of protection maybe.

    The larger types often are mounted in the mains power switchboard and have a better operation envelope, usually with better current capability. Some even have gas filled gadgets in them.

    Of course you could use a lightning deterrent system where radioactive gadgets on poles negatively ionise the air to reduce the leader potential.[/QUOTE] What's the half-life of these R/A gadgets?[/QUOTE]

    In the case of a reasonable strike on your home or the power pole out front, you really can't expect much protection because of the amplitude.[/QUOTE]amperage?[/QUOTE]

    The best protective method is to remove power plugs from sockets and isolate gadgets whenever lightning activity is present.
    At this location we have odd violent summer electrical storms, low cloud cover as low as 800 feet, simple ground strikes, as many as 1000 per hour in a twenty kilometer square.
    So you learn to live with it. These storms here usually pass in thirty or so minutes.

    If we want to keep sensitive equipment we have a plug out routine, especially with antennae.
    Some special power supplies can provide filtered controlled AC but again you get what you pay for.

    The most common idea is to insure all your devices against fire, theft, and make especially sure a reasonable lightning cover is included.
    Most people gamble that their items will survive so don't act to avoid problems.

    One such fellow was working on his computer during one of these storms, a loud bang happened and the lights went out, as this happened a smoking thing bounced across the floor near him, on investigation he found it to be the glass housing of the screen in his now demolished video recorder.
    The damage in that home was substantial, every TV, clocks, stove, washing machine microwave, garage door mechanism, aircon, a couple of computers, video player etc.
    Probably the only things that still worked were the lights that hadn't been switched on.
    It was likely the external TV antenna had been hit.
    A surge protector probably would not have been much protection in that case.

    I would imagine your machine wouldn't have been turned on but the system is still powered and would still be affected.[/QUOTE]Interesting! Even when powered, but turned off, a voltage (or amperage) spike, could cause damage?[/QUOTE]
    Very often these kinds of instances result in the power supply being destructed, primarily because it is a switchmode system and the solid state devices fail before the time constants in the output voltage rails is achieved, but oddly enough you may well find that your hard drive has also been affected.
    More often the other components seem to escape damage. Strange!

    Your mention of allergies[/QUOTE] - a feeble attempt at humor, mate:) [/QUOTE] to electrical activity is interesting, as you probably know the cloud base is incredible negative. (the top of the cloud is incredibly positive)
    There is a ground element which rises from the ground to establish the leader, this jagged component rises up to about 6 metres from the ground[/QUOTE]aah yes! you know yer stuff. That's why the bolt goes up, not down!!![/QUOTE]...


    Commisserations. qldit.
    [/QUOTE]
     
  5. kiwiguy

    kiwiguy

    Joined:
    Aug 17, 2003
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    17,584
    When the PC is "shut down" (powered off) the PSU is still connected and alive, and subject to voltage amplitude (spikes) (These cause "amperage" to flow as fault current when the PC fails).

    The maximum fault current deliverable by the power grid at this location is ~26 kA (26,000 amps).

    Even if the voltage was not overly high in amplitude, thats an instantaneous 8,000 horsepower in terms of actual energy.

    Now just imagine the cheap surge diverters trying to absorb that ...
     
  6. technaught

    technaught Banned Thread Starter

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    Seems like the most expensive SS'ers couldn't absorb that more than once... How then can some manufacturers offer a warranty???

    Does a desktop power supply unit have a higher tolerance to spikes, than do the other innerds in the desktop?
     
  7. kiwiguy

    kiwiguy

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    The more expensive ones will be relying on absorbing enough to cause the rapid failure of the primary protection device (fuse or circuit breaker) before they give up, which will still be a lot of joules in that few microseconds. The rest of the cost of the "expensive ones" is the insurance premium built into the cost.

    The desktop PSU is the only thing that has any "tolerance" in that respect, the "innards" rely on something upstream to ensure that no spikes are seen.

    On a PC that has more than one "connection" to the outside world (power and phone line for example) the risk is high that EPR (earth potential rise) caused by power system faults and lightning will enter the PC, with one having a higher EPR that the other, creating the voltage "difference" that kills things. Cordless phone base units are frequent casualties for this exact reason.

    Since the days of my first PC (1981) I have never had a failure resulting from power system faults here however. Most of the urban power cables here are underground and less subject to it.

    On the other hand I have recently bought a country cottage, where the power lines are miles of overhead. Everything there has a surge diverter on it, but I realise that a good strike would take them as well. Ideally I should fit a larger version at the main switchboard.

    For that event I have something called "insurance".
     
  8. qldit

    qldit

    Joined:
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    3,390
    Good Evening Happy Chappies, gee kiwi we must compare notes sometime, I made them rewrite the lightning safety warning in the front of the phone books here years ago. LOL
    You would be using the same MENS system there in Kiwiland I imagine.

    Yes the old lightning is incredible, the deterrent devices I mentioned are often around the ramp areas at airports, I have no idea what isotope they use but they do apear to reduce strike effect.
    I haven't actually played with one but imagine they would be a needle point ioniser idea, which means routine replacement. Probably Tritium or something like that.
    I did ask what happens if one is struck by lightning and vapourised?
    The answer was "That doesn't normally happen"!

    I first experienced these things at Nadi Aiport in Fiji mounted on 60 foot poles, a bit of a pain for wingtips, especially growing wingtips.

    Lightning and avoidance was part of my professional area, and I have always loved observing good displays.
    Had an odd close call to the point of really smelling the Ozone and having the hair stand up on one scary occasion. It is pretty noisy up close! When you smell it strongly you know it was close. (About fifteen feet away)

    Your question about amperage is difficult to answer, in fact it is possible when massive strikes happen that the actual earth potential in a local area can shift substantially and create a difference between nearby areas, especially affecting common connected devices, like phones and data transnission cabling and cause damage that is virtually impossible to explain.
    The high voltage transients can appear through the earthed or grounded system rather than the mains power circuit.

    Mains power systems commonly use a MENS (multiple earthed neutral system) where the neutral is earthed every five poles or so, in domestic systems the mains neutral is also generally earthed at the mains switchboard as a further attempt to provide protection and maintain the neutral at the earth potential.
    A copper coated stake is generally used here near the switchboard. (Which is most liely a waste of time)

    This is in direct contrast to Tesla's original scheme where active and neutral would float, and is why he damaged the power station generators with one of his experiments.

    If a strike hits a power pole, (with MENS) the major damage is generally contained within a limited radius with this idea.

    I better shut up, I became interested in negative ionisers for asthmatic situations and it does appear helpful for anyone with that problem, but the things need to be tested regularly to ensure they have no ozone output.
    There is a lot of misguided information on these devices in those circles.

    Summing up, the best protection is pulling the power plugs completely from the wall.
    Cheers, qldit.
     
  9. JohnWill

    JohnWill Retired Moderator

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    Messages:
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    Funny this topic should come up, we recently had a large power surge here. A high voltage line running above the residential distribution lines had a tree fall on it and it contacted the lower voltage lines that feed all the transformers. I ended up getting a really high voltage here, I measured 150V on the 120V lines, and I think it got higher than that at first. All the UPS units were beeping, thankfully they managed to disconnect and none of that equipment was damaged. However, I did lose several wall-wart power supplies for various things, and some light bulbs.

    It can happen at any time. :)
     
  10. qldit

    qldit

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    Good Morning John, and everyone, yes the practice of running the 3 phase lines above the ordinary supply lines is common and that problem is always present. Of course more often those lines are needed to allow phase loadings to be averaged out in different areas for overall balance and also be available for 3 phase consumers.
    We have an active ongoing tree pruning process here and also it is prohibited to plant certain types of trees in proximity or under power lines.
    The odd accident still happens where similar situations as yours occur.

    I am rather cautious about these switchmode power supplies, as you would be aware they are now common in "plug packs" for powering all kinds of gadgets, in many cases they are listed as being 110-230 volts which is kind of scary.
    We operate on 240V 50 Cycles here so they immediately are questionable.
    With some tests carried out on mains at various times in problem circumstances I have seen voltages as high as 260V so the close rating would be very hazardous.
    I have no idea how they work, but they do work equally well on 110V, maybe the chopper changes frequency or something. They do seem to run quite warm!

    In places where greater sensitivity of strikes affecting multiple systems exists, such as near sub-stations or transformer farms, an extra earthed line is usually run on top of the towers or posts for a kilometer or so with greater earthing ability to preclude problems from hub area strikes.

    It is an incredibly interesting subject, as Kiwi mentioned the possible transient paths into a domestic situation as apart from the power lines, are phone systems, cable TV systems, antennae, domestic appliances with high reactive elements and inductive lines.
    Then there are always new unthought of things, like electronic mains modulation devices which can also produce other odd effects. (apart from switching electric water heaters)

    With the advent of plastic plumbing and drainage pipes a new plethora of odd things happens when buildings receive heavy strikes, one woman was having a shower and received a decent "hit"!
    Other cases where concrete slabs steel reinforcing rods have issued sparks up through the floor have happened.
    Progress has downsides.
    My home has copper water pipe throughout, (including underground) power feed is 5 feet underground from a street aerial system via a steel earthed post system I purposely installed with this consideration.

    In the past tens years the only damage I had was my security system which suddenly operated when a strike happened a kilometer or so distant.
    I forgot about all the sensor wiring unshielded inductive effect when I installed it.
    Processor operation was destroyed.

    End of waffle on......
    Cheers, qldit.
     
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