Network connecting laptop to PC and grounding issue ?!?

Discussion in 'Asus' started by Skybuck Flying, May 16, 2011.

  1. Hello,

    As you might now by now I am investigating grounding issue's ;)

    The ammount of issue's with it is already staggering ! ;) =D

    My latest question/wonderings is about laptops.

    Laptops can either work without power cords/on batteries... or with power
    cords even non-grounded power cords.

    My first question is:

    What if a battery-powered-laptop is connected to a PC via an ethernet cable
    and the laptop has a small defect... for example the laptop fell onto the
    ground and has slight issue's.

    Or perhaps it has a small leaking current by design.

    Could this cause a PC from getting damaged even if the PC is grounded ?! ;)

    I would guess not because the motherboard clips on the ethernet ports are
    touching the case... so perhaps any additional current/volts which might
    travel via ethernet are immediatly transferred onto chasis and into ground
    ?!?

    Or perhaps ethernet is not designed for situations like this and
    volts/ampere will directly go into motherboard and damage stuff ?!?

    Same question could also be asked for cable modems and such.

    Bye,
    Skybuck.
     
    Skybuck Flying, May 16, 2011
    #1
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  2. Skybuck Flying

    Paul Guest

    Ethernet is galvanically isolated. The Ethernet interface uses tiny transformers,
    and the Ethernet differential pairs run through a transformer. By doing so, it
    eliminates issues with potential difference between equipment ground.

    http://en.wikipedia.org/wiki/Galvanic_isolation

    The Ethernet transformers are housed in a plastic chip. In this schematic,
    you can see the transformer package for the Ethernet, on the right hand side.

    http://www.avrfreaks.net/wiki/images/EVK1100_ETHERNET_Pinout.jpg

    This is what the plastic package with the transformers looks like physically.

    http://www.cetus.com.cn/pic/LCZ3N1JA.jpg

    A gigabit Ethernet interface, has more transformers inside the plastic
    chip, than a 10/100BT interface would use.

    Paul
     
    Paul, May 16, 2011
    #2
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