Motor brushes spark do
Large current at startup, and sparks during normal operation there is no spark. Can be excluded from the following:
1, check the motor for carbon brush length is too short, to lifeline, resulting in pressure is too small brush on contact without slip rings
2, check whether the spring loaded pressure fit, if too small can cause jumps brush discharge
3, check the slip ring surface finish, if you too can increase the contact resistance of electro-brush lead sparks
4, check the electric rotor to ensure resistance to normal, no-turn short circuit
5, check that the bearing is oil gap is too big, cause the rotor rotating slip ring brushes to beat a large quantity, check that the sliding ring radial runout is excessive. Elastic brush brush caused the spark
6, addition of brush and previously used, brushes on conductive currents and friction speed required.