Question

Mention the resons for poor commutation

Answer 1

Reasons for poor commutation:

Explanation:

• Poor mechanical conditions like uneven surface of commutators, vibrations of brushes etc.
• Poor electrical conditions such as increased voltage between the bars of commutators, increase in the current density of brushes etc.
• Practically Ideal Commutation is not possible.
• This is mainly due to the fact that the armature coils have appreciable inductance.
• When the current in the coil undergoing commutation changes, self-induced e.m.f. is produced in the coil. This is generally called reactance voltage.
• This reactance voltage opposes the change of current in the coil undergoing commutation. The result is that the change of current in the coil undergoing commutation occurs more slowly than it would be under ideal commutation.