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Are PC surge protectors needed in the UK?

Discussion in 'Electronic Repair' started by Lem, Jul 8, 2004.

  1. If you do the sums, it cheaper for them to leave out the surge
    suppressor components altogether and just pay up on any such incident.
    Power line surges (in the UK at least) is a vanishingly insignificant
    source of damage.
     
  2. Been there, done that :-(
    Many of the mains surge protectors also include connectors for looping
    a phone line through them.
     
  3. I think you need to be more quantitative here. Kilometres of air could
    not stop what, exactly? They certainly do a good job of protecting me
    from lightning strikes in the next village.
     
  4. w_tom

    w_tom Guest

    Lightning is a connection from cloud to earth borne
    charges. Electricity travels through kilometers of
    non-conductive air. Why would some millimeters of air between
    two RCD contacts stop same electricity? 1,000,000 mm of air
    did not stop lightning. Why would 4 mm of RCD air stop what a
    million mm could not?

    The bottom line is this. Nothing is going to stop
    lightning. Lightning protection is about shunting - also
    called diverting, redirecting, or electrically connecting - to
    earth ground. Any protector that claims to stop or block
    lightning (such as in the RCD question) is simply promoting a
    myth. And yet that is exactly what many people do - promote
    the myth - when they recommend plug-in protectors.

    In response to the OP's question. 4 mm of air inside the
    RCD (open switch contacts) is not going to stop a potentially
    destructive surge.
     
  5. Haven't had anything break that was plugged into it, although the power
    has flickered or quit many times during storms. But then, the TV and VCR
    are still working, and they're not on a surge protector.
     
  6. Pyriform

    Pyriform Guest

    I am not naive enough to think that my little "surge protector" would
    save anything from a full-on lightning strike. The issue is whether one
    might reasonably expect more modest voltage transients to occur on the
    mains supply (and phone line) which can be safely absorbed by such a
    device, and which might otherwise disrupt or destroy delicate
    electronics (equipped, perhaps, with rather cheap PSUs).

    I freely admit to not knowing the answer. Your contributions make good
    points about the requirements to be met in order to achieve 'proper'
    surge protection, but do nothing to address this question.
     
  7. In message <>, w_tom <>
    writes

    [top-posting corrected]
    No, current travels through kilometres of conductive ionised air. First
    you need a strong enough potential difference to produce a strong enough
    electric field to cause that ionisation. Then there's a complicated
    process by which the ionisation spreads to produce a complete channel.
    Because the potential difference across _that_ gap, and hence the field
    strength, may now be insufficient to produce ionisation. Never mind how
    many megavolts there were between cloud and earth, the question is how
    many there are across that contact gap.

    That's why I asked you to be quantitative. Qualitative language like
    "same electricity", "surge" and "transient" is not helpful here. Do you
    mean a current, a potential difference, an electric field, or what?
    Now you're confusing two different things. Most plug-in protectors that
    I've encountered do not rely on open contacts (as in the RCD) but use
    some form of voltage-dependent resistor and/or spark gap to shunt the
    excess potential difference to local ground. To be sure, there may be so
    much inductance in the system that they are ineffective, but that's a
    different issue.
    It _will_ stop a "surge" or even a "transient" up to some threshold
    potential difference. What's that value, and how is it related to what's
    going on in the sky outside?
     
  8. someone

    someone Guest

    A brownout is generally recognized as planned voltage cuts - or
    undervoltage.
    My utility in the US routinely implements 3% and 5% voltage cuts to shave or
    reduce peaks (and thereby save $' when buying power).

    There is also the issue of spikes and harmonics.

    Given a current laptop/desktop will be ~ $800USD to ~$4000 for a high
    performance system and a UPS sells for $40 - why subject a computer
    to unexpected power events? What is the value of the data on the hdd(s)?
     
  9. This just isn't an issue in the UK, about which the original question
    was asked. Maybe it's more of a problem in the US for some reason?
     
  10. Ron Reaugh

    Ron Reaugh Guest

    No, there's no hardware nor data worth saving in the UK<G>.
     
  11. w_tom

    w_tom Guest

    A 3 or 5% reduction in voltage, also known as a brownout to
    the utility, is totally irrelevant to electronics and
    especially irrelevant to computers. A computer works just
    fine even when incandescent bulbs dim to less than 40%
    intensity. Even demanded in Intel specifications. IOW what
    the utility calls a voltage reduction is full power to the
    computer. Utility would have to decrease voltage more than
    20% for a computer to see a brownout. But if utility voltage
    drops that low, then electric motors may be damaged. IOW
    voltage too low to damage electric motors is even full power
    to a computer - which demonstrates how resilient a computer
    really is.

    BTW, utility does not institute a voltage reduction to save
    money. Voltage reductions are a last ditch effort to avoid
    rolling blackouts.

    Spikes and harmonics are (or should be) irrelevant to a
    computer. Again, because the computer is so resilient.
    However that internal computer protection assumes the building
    has a 'whole house' protector so that spikes cannot overwhelm
    computer internal protection.

    All of which is irrelevant to HD protection. Either the
    power supply will output correct power or it will shutdown.
    This, of course, assumes the computer assembler had basic
    electrical knowledge and did not install those 'defective by
    design' $25 or $40 power supplies. But again, this was
    explained earlier.

    There is nothing cost effective adjacent to the computer. No
    UPS nor power strip protector that will protect computer
    hardware. Computer internal protection assumes the building
    has implemented a 'whole house' protector on AC mains
    connected less than 10 feet to central earth ground.
    Protection as it was even done and well proven before WWII.
     
  12. w_tom

    w_tom Guest

    First, plug-in surge protectors would not even provide
    effective protection meaning that they are not even relevant
    to the originally posted question. Furthermore, the little
    surge protector does not absorb even modest transients.
    Absorbing is not what they do.

    Second, a full-on lightning strike is why we install
    protectors. Modems already have significant internal
    protection as part of design and to meet industry
    requirements. Protection that can be compromised by a full-on
    lightning strike.

    Typical frequency of potentially destructive surges is once
    every eight years. That number varies significantly even
    between adjacent towns. So how frequent is your
    neighborhood? Without information such as underlying geology
    and manmade buried objects, weather trends, etc; then your
    only valid information comes from history provided by long
    term neighbors. Yes, even installation of new buried
    utilities can change those trends.

    'Whole house' protectors and earthing is so inexpensive that
    US telco companies install same, for free, at every customer
    interface. Question is whether the £1 per protected appliance
    is necessary for a destructive transient that might occur once
    every ten or so years. Points one and two define why you
    would install that protector.
     
  13. Pyriform

    Pyriform Guest

    Or to avoid the expense of bringing additional generating capacity
    online, thereby saving money...
    A PSU shutting down is not irrelevant to HD protection. Shutdown at the
    wrong moment (especially with the wrong operating system) and you end up
    with a badly trashed filesystem.
     
  14. Eric Gisin

    Eric Gisin Guest

    I have operated computers much further from 120V with absolutely no problems.

    Once at the end of 100ft extension cord along with 1500W heater, lights
    dimming.

    The other time at 130V, light bulbs popping every month.

    Even on a generator nearly out of gas I had a minute to shutdown my system, no
    corruption occured.
     
  15. someone

    someone Guest

    True - my opinion as well - perhaps you could convince my local utility re
    this procedure being used on a daily basis.
    Perhaps you could explain the half dozen UPS I have seen that operated
    correctly and interrupted close in electrical faults.
    Naturally the UPS were scrap after the electrical event - but the protected
    electronics were ok.
    $40 UPS vs $800 desktop or in one situation $200 - $300 UPS vs. $5000 of
    servers.
     
  16. w_tom

    w_tom Guest

    Was UPS between AC mains and computer? No. UPS and
    computer both connect to AC mains just like light bulbs. In
    fact it would be same protection if both computer and UPS
    shared same wall receptacle. Any transient from the
    receptacle confronts UPS and computer equally. However
    protection inside a UPS is often so grossly undersized that a
    surge too small to damage a computer might still damage the
    UPS. Furthermore, some computers can even act as surge
    protectors - shunt a destructive surge so that it does not
    seek earth ground via other computers.

    Until you define specific circuits - including how every
    wall receptacle is wired, then I cannot provide more
    information.

    I cannot say exactly why that particular event happened.
    But above is one reason why a UPS may be damaged and computer
    is not. Computer power supplies have internal protection.
    Protection so sufficient that there is little adjacent to a
    power supply that can enhance protection. But computer
    internal protection can be overwhelmed if destructive
    transients are not earthed before entering the building.

    Bottom line is this. You had UPS failure. Therefore you
    have no effective surge protection. Even surge protectors
    must not be damaged due to a surge.

    To provide a better answer, do as I do - autopsy the dead
    body. Replace the defective part to learn what has actually
    been damaged. Autopsy only complete when the failed unit is
    fully functional.

    If a server farm has no 'whole house' protection and a single
    point earth ground, then no UPS or plug-in protector is going
    to do anything better. In fact, it is just not a reliable
    operation if 1) every incoming utility line does not enter at
    the common service entrance all connected to the single point
    earth ground and 2) building does not have necessary 'whole
    house' protector on incoming AC mains. From Sun Microsystems
    planning guide:
    http://www.sun.com/servers/white-papers/dc-planning-guide.pdf
    If you are suffering transient damage, then the human is
    reason for failure. What Sun writes is so well proven and
    understood that it was standard even before WWII. Protection
    is only as effective as its earth ground.

    As for your brownouts - if any voltage is too low for a
    computer, then the utility has grossly violated national
    standards. A PUC call would create a massive response - if
    your AC voltage drops so low as to be problematic to a
    computer.
     
  17. Ron Reaugh

    Ron Reaugh Guest

    That's simply wrong/false. A good UPS or good surge protector WILL protect
    a PC. Do you understand the concept of common mode?
    That's simply wrong/false. There is nothing magic about 10 feet
    except that an electrical pulse travels about that far in 10 nanoseconds.
    What do you suppose the risetime of a lightening bolt is and how
    does that relate to that 10 feet?
    Define "central earth ground" and what it's important characteristics are.
    Where is the "central earth ground" on an airplane, car, ISS or on the
    Antartic pole US base(over a mile thick cold pure ice)? Are all PCs and
    electronics gadgets there doomed?
    Ever heard on the concept of a Farady cage?
    Yes, for those who actually understand it. What does the "central earth
    ground"
    look like at a major power station, substation or hydroelectric dam?
    Where's it located?
     
  18. w_tom

    w_tom Guest

    Again, the trashed filesystem is a problems of FAT and other
    simplistic file systems. It is not a problem to superior
    (journalizing) filesystems.

    Will a disk drive write to the platter as voltage drops? Of
    course not. The disk drive controller is a complete computer
    that also monitors voltage. It does not matter to disk
    hardware when power is turned off. But it does matter to some
    'simplistic' disk filesystems that power is not removed during
    a write operation.

    Just another reason why FAT was obsoleted by HPFS which in
    turn was obsoleted by NTFS.
     
  19. w_tom

    w_tom Guest

    Ok sir. Explain to us how a plug-in UPS provides common mode
    protection. Also cite the manufactuer's spec that claims that
    common mode protection (and good luck).

    Also please explain how those 130 ohms impedance in 50' of
    12 AWG wire is not significant when earthing even a trivial
    100 amp surge?

    In the meantime, please explain how earth ground at a hydro
    electric plant is at all related to single point earth ground
    for a building, for a PA or stereo system, for the PC board
    layout of A/D converters, or any other simple electronic
    system where ground loops can be a problem. You do understand
    the concept of ground loop? Good. Please then show us how
    the ground at a power station has any relevance?

    Now for the completely irrelevant topic of ground in an
    airplane:
     
  20. Pyriform

    Pyriform Guest

    I say absorb; you say shunt. We mean the same thing. Energy that would
    have entered the 'protected' load instead goes somewhere else. So unless
    you are arguing purely on the basis of semantics, your claim that even
    "modest transients" are not absorbed by plug-in surge suppressors is
    clearly false. What I want to know is whether such transients are
    actually found, and whether they pose a threat to 'unprotected'
    equipment.

    Your "unless it protects against everything, it protects against
    nothing" argument is not entirely convincing.
     
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