Question

Q. The potential of a lightning discharge is 25 million volts and maximum intensity of current rating is 200,000 Amp.

(a) What is the power of discharge in kws?
(b) What is the energy spent (in kws) in the lightning if it lasts for 0.001s ?​

Answer 1

Answer:

The peak current in lightning strikes varies considerably depending on cloud height above the Earth’s surface, whether it is the first stroke or a subsequent stroke in a multi-strike event, and its polarity (i.e., positive or negative lightning). Lightning expert Dr. Vladimer Rakov compiled lightning statistics from a large number of lightning strikes and a variety of sources. He found that the peak current for over 98% of all cloud-to-ground (CG) lightning strikes ranged between 5 kA - 200 kA. However, about 1% of all lightning strikes exceed 200 kA, and about 1% of all positive lightning strikes (0.1% of all strikes) may exceed 350 kA. This has been considered the “worst case” scenario for lightning protection of electrical power systems (CIGRE 2013 report).

The potential (or voltage) differential between the cloud and ground below is a function of cloud height and polarity of the thunderstorm. Negative lightning typically originates from the lower portions of a thunderstorm, and thus tends to have lower potentials. Positive lightning tends to originate from the upper parts of the storm cloud, so potentials tend to be higher. The initial cloud potential for negative lightning is typically in the range of 50 - 100 million volts. Some of the most powerful positive lightning bolts have an initial potential that can exceed 1 billion volts. The most powerful positive lightning strikes can pack over 100 times the energy of a typical negative lightning strike, making them exceptionally dangerous.