prevents signals fromgetting onto the shield and then 'injecting' themselves inside to the center conductor. Also makes the coax 'higher' quality.Work on analyzing 'shield induced' noise may appear somewhere. The beads help prevent that.
uitive. =A0But this professor could back up his statements both with the ma= th and with experience.
A related factor, I would think, would be the voltage drop across the wire. Assuming your 100ka strike, a 50ft run of 10gauge would develop 5,000 volts. A 50 ft run of 4gauge would develop only 1,200 volts. At the higher voltage, the likelihood of the strikie flashing over to something other than the desired wire increases.
But this professor could back up his statements both with the math and with experience.
I assume that is based on resistance.
Lightning is a very short event which means it has relatively high frequency components (from a previous post most of the energy is below
100kHz.). That means inductance is likely more of a problem than resistance. Also skin effect. Larger wire has a major effect lowering resistance, but not much effect on inductance and skin effect. Both are covered in a link I posted.
Downconductors are #3 or larger. They are that large for reasons also in a previous post.
================================================= For power wiring, the 1968 NEC had correction factors for skin effect on large wires. I don't know when the tables were dropped; the correction was probably rolled into the other tables. The AC resistance of a 4/0 wire is increased by about 0.5% over the DC resistance. The diameter of a 4/0 stranded conductor is about 0.5".
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