New fixed phase arc-extinguishing lightning protection device can reduce lightning accident of the transmission line andimprove the reliability of power supply. In order to further verify its performance

we study the mechanism of action and effect of the device. This paper introduces its operating principle

through arc model simulation and arc-extinguishing simulation

we get that the arc can be cut off at the first zero crossing;in the ideal environment

arc can be extinguished within about 1.4 ms under the effect of the high-speed impact airflow without re-ignition. The arc-extinguishing tests indicate that the device can protect insulator strings

avoid action of relay protection and reduce the rate of the lightning trip-out of transmission line in a very short period of time. Then effectiveness and practicability is proved.