The Collaborative International Dictionary of English v.0.48:

Electrepeter \E`lec*trep"e*ter\
   ([-e]`l[e^]k*tr[e^]p"[-e]*t[~e]r), n. [Electro + Gr. tre`pein
   to turn.]
   An instrument used to change the direction of electric
   currents; a commutator. [R.]
   [1913 Webster]