troubleshooting chart for dc rlectrical machines

Discussion in 'General Electronics Chat' started by gjo, Jun 11, 2013.

  1. gjo

    Thread Starter New Member

    May 22, 2013
    On this troubleshooting chart that i have for dc electrical machines it says for commutator sparking of brushes that a probable cause is "commutation winding defective." What do they mean by mean by commutation winding defective?
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    The rotor windings connected to the copper terminals are usually shorted out with the debris from the carbon brushes.
  3. tinkerman

    Active Member

    Jul 22, 2012
    Sparking could be caused by an open coil or shorted coil too. Usually the coils terminate at adjacent bars on the commutator. (Not always. Wave wound armatures are different). An open coil will cause arching at the defective coil/bars and if operated in this conditioin will quickly destroy the commutator. Very noticeable with a ring of fire on the commutator, distinct sound and loss of power. If caught early you can short the bars bypassing the open coil but this naturally reduces output.