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Surge Protectors, they seem to be worthless.

Discussion in 'Electronic Repair' started by daveem Dave M, Sep 11, 2003.

  1. I was wondering if any one here knows of a Surge Protector that actually
    works?
    I remember some time back when I was working in a TV repair shop, people
    would often bring in sets that had been damaged from power surges, and
    even though they had their sets plugged into surge protectors, the
    things never worked. Any tips in this area would be appreciated.
    Thanks, Dave
     
  2. Sofie

    Sofie Guest

    daveem Dave M:

    Yes, surge protectors do "help" to protect equipment.... BUT some surges can
    still get through and do damage.
    It is kind of like have seat belts and air bags in your car...... they will
    help you minimize injuries in an accident but if you hit a logging truck
    head-on at 60 mph they won't do much to save your life.

    As a side note: One of the best types of surge protection is to use a UPS
    which isolates the equipment from the AC line but you still have the
    possible issues of the ground connections if they are not 100% up to par.
     
  3. Jeff Wiseman

    Jeff Wiseman Guest


    Many protectors today use MOV technology whcih has some disadvantages. Others, like the Brickwall series use "Series mode" protection. They have patents on some of this so others are limited in some ways for using them. For example, Adcom is using this technology in their new protectors with "lightning protection" but I believe that they pay royalties to Brickwall, etc.

    A bit of discription on this can be found at

    http://brickwall.com/howwork.htm

    - Jeff
     
  4. JM

    JM Guest

    quoting:

    One of the HUGE misconseptions about surge protectors is that people think an
    inexpensive store bought plug-in surge protector will stop LIGHTNING. Those
    things can only stop the smaller "power line surges", not lightning. Even
    then, they do wear down after a while, and will need to be replaced.
     
  5. I was wondering if any one here knows of a Surge Protector that actually
    Any surge protector will work ... to a certain degree.

    Different surge protectors will have different tolerances, which are rated in
    joules. The higher the joule rating, the better the protector will supress
    larger surges.

    However, no surge protector will protect from a lightning strike. Furthermore,
    surge protectors do wear out from use to the point where they are not any
    better at supressing surges than a regular six-outlet strip with no surge
    supression. - Reinhart
     
  6. Jeff Wiseman

    Jeff Wiseman Guest


    Only if you are talking about MOV type protectors that are designed to absorb the excess energy. They are supposed to look like a short circuit to the surge so obviously, the better the "short", the better the protection. Since series mode protectors look like an open circuit to the surge, the opposite is true (i.e., 0 Joules is the best since nothing gets through except the standard power).


    Not exactly true. It is true if you are referring to the typical MOV based protectors


    Again, this is really only true of MOV based units. the MOVs absorb the surges but are destroyed a bit each time they function. This is not the case for series mode protectors like those used in mission-critical areas.

    - Jeff
     
  7. James Sweet

    James Sweet Guest

    They protect equipment against spikes generated by inductive loads starting
    and stopping but a lightning strike will blow up even a high end surge
    protector.
     
  8. Many times the problem is that the surge comes in though lines that are not
    protected. Many TVs are connected to cable, sat, ant, stereo recievers, and
    phone lines. If every line into the system is not protected, one protector
    on the ac line of the TV may not make much difference.

    I have a TV and DVD/receiver combo in my shop right now that were both
    plugged into a surge suppressor. The antenna line was not protected with a
    lightning arrestor nor was it grounded. The ground foils on the circuit
    board of the receiver are like burned spaghetti, there are a dozen or more
    fried parts in the TV, tuner is cooked in the TV, and the power supplies in
    both appear to be intact. This was an extreme example but we see similar
    problems with unprotected and poorly grounded sat and cable lines as well.

    We sell the Panamax and I have used the ESP stuff, and I have very rarely
    seen components damaged when on these, with all lines protected. Panamax
    has a lifetime warranty and units that cover all lines, as well as
    undervoltage protection on their better units. They seem to be well made
    and they are an easy company to deal with. They will typically send a new
    unit to anyone who returns an old one for testing/evaluation.

    Other problems are that MOVs used in surge protectors degrade with repeated
    surges and grounding in the ac service and on incoming lines may be poor.
    The best surge suppressor is useless if there is not a good ground.

    Leonard Caillouet
     
  9. Mike Berger

    Mike Berger Guest

    Your surge protector won't do much good without being connected to
    a good ground. A long power cord on the surge protector could mean
    a dubious ground.

    I've gotten great service from the Tripp-Lite Isobar Ultra series. Aside
    from the conventional MOV surge protection, they also have high and
    low frequency filtering between pairs of outlets. I've had three die
    while protecting the equipment behind them, and they were replaced
    under the lifetime warranty at no cost. I've got a couple dozen in use.
     
  10. Sofie

    Sofie Guest

    Leonard Caillouet is quite correct....... a lot of equipment with 2 wire
    ungrounded power will use a MOV quite effectively across the line......
    more than once have I seen that arrangement burn up, short the MOV, and
    save the equipment from over voltage.
     
  11. Al Savage

    Al Savage Guest

    All consumer-class UPS (that I'm aware of) are not online UPSs but
    standby mode only, so that the thing is a voltage monitor + battery
    charger until the line voltage goes out of range. I doubt that this
    class of unit is going to provide much protection.

    OTOH, the commercial class UPSs I've worked with regen the output, and
    they are excellent filters :) Expensive, and often a bit warm though.
     
  12. w_tom

    w_tom Guest

    What do you want to do? Stop a surge or earth it?
     
  13. Loren Coe

    Loren Coe Guest

    iirc, the 'ideal' path is hot to neutral. what many folks
    don't understand is that the MOV actually uses the wiring
    as resistance and reflects hi impedance upstream. this
    is how they suppress lightning and why there can be no
    100% surefire protection (w/simple mov's) --Loren
     
  14. Loren Coe

    Loren Coe Guest

    nothing about voltage, just the impedance, as it rises the
    likelyhood of the lightening taking a alternate path increases.

    i am no expert but trained in electronics and have worked
    on equipment damaged by lightening and have advised customers
    on prevention.

    my recollection is from a "white paper" read some years ago,
    as the MOV reaches its trip point and starts conducting, the
    current thru the power wires increases (of course) and for
    that instant the voltage drop spikes and the line presents
    almost infinite imepdance. i thought of it as inductive
    reactance. again, iirc. --Loren
     
  15. w_tom

    w_tom Guest

    First learn about constant current sources. A destructive
    surge is driven by a constant current source. IOW voltage
    will increase, as necessary, to maintain that destructive
    current flow through appliance. Furthermore, concepts of
    impedance are consistent only within certain voltage ranges.
    When discussing surges, breakdown voltages must also be
    considered.

    Impedance is important to a surge circuit. So much so that
    wire is no longer considered a conductor; wire becomes an
    electronic component.

    For example, let's say a plug-in protector has shunted a 100
    amp surge. Assume a 50 foot path to earth ground via
    neutral. Wire resistance may be less than 0.2 ohms. But wire
    impedance could be 130 ohms. That would be a (less than)
    13,000 volt difference between surge protector (and adjacent
    computer) and earth ground. At these voltages, a surge will
    also find other (destructive) paths to earth - because wire
    impedance is significant.

    Wire impedance is why an effective (whole house) surge
    protector makes a short (typically less than 10 foot)
    connection to central earth ground.
     
  16. By Top posting again w_tom has managed to avoid the gist of what loren was
    saying.
    Which is what loren was saying
    Also consider the surge arrestor built in to the appliance with the
    relatively high impedance wiring back to earth this surge arrestor keeps
    power dissipated by this device to a minimum Also by effectively shunting
    the surge to a common point within the device it helps keep the Voltage
    across individual components in the device to a minimum (and often
    bearable/surviveable level) throw in an isolated input though (such as the
    Line Circuit for a modem) and damage happens.
    Wire impedance is also one of the reasons that individual device surge
    protection can often be more effective than 'whole house protection' in the
    event of a near strike. In the event of a Direct strike though all bets are
    off. It also effectively counters one of w_toms favourite fallacies that
    Lightning seeks an Earth in a phone line (usually connected via max of
    single strand 0.28mm square copper wire) rather than MEN earth (connected
    via at least 2.5mm square multi strand copper cable) but then again w_tom
    never lets facts get in the way of his Fantasies

    This just highlights w-toms rule of selective application ie that a
    Lightning surge will have no trouble being shunted to earth via reatively
    high impedance phone cabling (single strand 0.28mm square copper wire) but
    will turn up its nose at comparitively low impedance mains cable.


    Correct and also the greater the likely hood of that path being destructive

    You probably have a better grasp on Lightning damage and protection than
    w_tom

    I would have to do the sums - remember though that a MOV never becomes a
    complete short it would not stop conducting if that happened which peversly
    is also why they incinerate in direct/near strikes.

    Regards
    Richard Freeman
     
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