Electric Current is used against Werewolf it immobilizes them and the more watts the more it does. At a certain point enough watts of current will keep a Werewolf from shifting, and to much could kill them.

Electric Current was used in Season 1 When the Argents had Derek locked in a cellar under the Hale house. Also in Season 2 when Boyd and Erica were locked up in the Argents basement. Also in Season 3 when the Calaveras had Derek and Peter locked to an electrified fence. Then again in Season 4 when the Calaveras had Scott locked up in Mexico.