After installing lightning arresters, when transmission lines are struck by lightning, the分流 of lightning current changes. Part of the lightning current enters adjacent pole towers via the lightning arrester wire, and part is grounded through the tower body. Once the lightning current exceeds a certain threshold, the lightning arrester activates and joins the分流. Most of the lightning current enters the conductors from the lightning arresters and propagates to adjacent pole towers. As the lightning current flows through the lightning arrester wire and conductors, due to electromagnetic induction between the conductors, coupled components are generated on both the conductors and the lightning arrester wire. Since the分流 from the lightning arresters is much greater than the分流 from the lightning arrester wire, this coupling effect raises the conductor potential, making the potential difference between the conductor and the top of the tower less than the flashover voltage of the insulator string. Therefore, the insulator will not flashover. This is why lightning arresters on transmission lines have excellent clamping potential action, which is a distinct characteristic of their lightning protection function.

Historically, lightning protection for transmission lines primarily involved reducing the tower grounding resistance, which is relatively easy in plains. For mountainous areas, longer radial ground wires or deep wells with resistive agents are often used at the four tower footings to increase the contact area between the ground wire and soil, thereby reducing the resistivity. Under industrial frequency conditions, the grounding resistance will decrease. However, during lightning strikes, the longer ground wire can result in a significant additional inductance value, causing the transient component L.di/dt of the lightning overvoltage to be added to the tower potential, significantly raising the tower top potential. This makes flashovers between the tower and insulator strings more likely, thus reducing the line's lightning resistance. Since lightning arresters have a voltage clamping effect, they are not too strict about the grounding resistance requirement, making lightning protection for mountainous transmission lines easier to achieve.