what do you mean by poor commutation
Answers
This is of machines.
A machine is said to be in poor commutation if there is sparking at the brushes and commutator surface.
Poor commutation can be caused by mechanical or electrical condition.
Mechanical conditions include :
1) Uneven commutator surface
2) Non uniform brush pressure.
3) Vibration of brushes in brush holders.
Electrical conditions are :
1) An increase in voltage between the commutator segment.
2) An increase in the current density at the trailing edge of the brush.
The poor commutation means sparking and bar burning of DC generators.
The improper position of the brushes mainly causes this, brushes placed in incorrect spaces, burned commutator, lousy brush contact, vibration, short-circuit, overloading, the brush chattering, very high or open resistance joints, open armature coil, poor balance of the rotor, grooved commutator, etc.