A transmission line arrester also known as a transmission line surge arrester is any arrester that is applied out on the transmission line to reduce the possibility.

The resulting wave when an electrical variation in a circuit such as a transmission line takes the form of translation of energy along a conductor, such energy being always equally divided between current and potential forms. The traveling waves propagate at close to the speed of light and can generate surges at 2-4 times the initial impulse under certain circumstances.

Impulse protective levels of an arrester:

a) Fast front protective level: The highest of either the steep current residual voltage or the front-of-wave impulse spark over voltage.

b) Standard lightning impulse protective level: The highest of the residual voltage at nominal current or 1,2/50 lighting impulse spark over voltage.

c) Switching impulse protective level: The highest of either the maximum residual voltage for the specified switching current or the specified switching impulse spark over voltage.