Lightning protection and grounding knowledge popularization, take you to understand clearly in 2 minutes!
Frequently Asked Questions
What are the three parts of a lightning protection device?
A lightning protection device consists of a lightning arrester (receiving device like rods, strips, nets, or overhead ground wires), a down conductor (connecting the arrester to the grounding device), and a grounding device.
What is the difference between lightning protection grounding and safety grounding?
Lightning protection grounding discharges lightning current into the ground, while safety grounding discharges power frequency short-circuit current. Lightning current is much larger, causing higher voltage drops and potential counterattack, whereas power frequency current is smaller and less likely to cause rebound.
Why might lightning rods require independent grounding devices?
Due to the severe rebound phenomenon (counterattack) caused by high voltage from lightning current, lightning rods and wires often need independent grounding devices to prevent discharge on protected objects.
What is high potential introduction?
When overhead power lines are struck by lightning or nearby, induced overvoltages up to several hundred kilovolts can travel along the lines into buildings. This is called high potential introduction and requires grounding to prevent injury.
What materials are used for lightning protection devices?
Materials must have sufficient mechanical strength and corrosion resistance. Typical specifications meeting these requirements also ensure dynamic stability (resistance to mechanical damage) and thermal stability (resistance to thermal damage) when passing lightning current.
