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Discussion in 'General Electronics Discussion' started by wafula, Sep 5, 2011.

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  1. wafula

    wafula

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    Sep 5, 2011
    Hi.i need a comparison between a single point grounding and star point grounding in relation to transients.Which one of the two is more efficient?
     
  2. davelectronic

    davelectronic

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    Dec 13, 2010
  3. wafula

    wafula

    14
    0
    Sep 5, 2011
    Thanks,but may be i needed to a little specific on this matter.I was looking at the type of grounding for example that would work best for like a solid state transmitter given that it includes,the Tx itself,the mast,the rf cable and power mains. We have had cases where radios have been burn off completely even when they have lightning arrestors.how could one avert such a situation?
     
  4. davenn

    davenn Moderator

    13,883
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    Sep 5, 2009
    Lightning arrestors will generally only give protection from non-direct/very close strikes.
    For non-direct/very close strikes, there's pretty much nothing you can do. Millions of volts and many 100's of amps is pretty difficult to contain and channel away from equip connected to a ready made lightning rod, aka antenna and tower.
    Very good storm damage insurance is the best protection ;) In my days of being a rigger on radio masts back in New Zealand for Telecom, the best you could do was to make sure your antenna was NOT the highest point on the mast/tower. 2 inch diam and 6ft long lightning rods were always the highest object. They were connected to extensive radial ground mats around the mast via 3/8 thick, 1inch wide copper straps running down the mast. Even wit hall that lightning would still periodically take out a system

    cheers
    Dave
     
  5. davenn

    davenn Moderator

    13,883
    1,966
    Sep 5, 2009
    Sorry, to answer your Q a little more directly...

    The type of earthing system in the building. every item should have its own ground wire back to the earth rod. ie. star system. DONT daisy chain equip just to save wire.
    The buried ground mat type will to an extent be dependant on the ground type (rocky/soft soils etc) Regardless of that you still will not use just a single earth rod into the ground. The common system I used was a star system out from the initial earth rod. Each leg of the star could be up to 20ft long and would be bonded to an earth rod every 5ft. You may have 5 or more legs (radials)
    Have a look here for some other links on the subject.....
    Technical_Reference/Grounding/

    cheers
    Dave
     
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