State the causes of sparking on commutator. – NABTEB QUESTION

The causes of sparking of commutator segments are:

(i) Shorted armature.

(ii) High Mica.

(iii) Worn-out Brushes.

(iv) Dirty Commutator.

(v) Armature Reaction.

(vi) Overloading.

(vii) Wrong position of brushes.

(viii) Earthed armature coil.