How Does Lightning Induce Voltage Spikes in Power Lines?

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Lightning induces voltage spikes in power lines primarily through the changing magnetic fields created by the lightning current, which generates an electromotive force (emf) in the lines. Additionally, lightning can deposit electric charges on the lines, similar to how a battery operates. The high-frequency alternating current (AC) produced by lightning leads to oscillating induced voltages in the cables. There is a possibility for the emf from lightning to counteract the generator's emf, potentially resulting in a voltage reduction rather than a spike. Understanding these mechanisms is crucial for designing protective measures against lightning-induced surges.
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How does lightning cause a voltage spike? Is it the changing magnetic field caused by the lightning current that induces an emf in the power lines, or are electric charges deposited on the actual lines (like a battery pushing charges). Is it possible for the emf of the lightning to cancel the emf of the generator, so that you get a voltage reduction instead of a spike?
 
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The em produced by lightning is a burst of high frequency AC, so the induced voltage in a cable would be oscillating in 'both directions'. It is 'AC coupled'.
 

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