long shunt
short shunt
differential compound
cumulative compound
MNA (magnetic neutral axis)
GNA (geometric neutral axis)
perpendicular to MNA
perpendicular to GNA
reactance voltage generated as a consequence of commutation
cross-magnetising the effect of armature reaction
demagnetising effect of armature reaction
all the above
rate of change of flux is minimum
rate of change of flux is maximum
flux linked with conductors is maximum
flux linked with conductors is minimum
to increase the resistance of brushes
to reduce the no. of turns in the armature coil so as to reduce the no. of commutator segments
to neutralise the reactance voltage by producing a reversing e.m.f. in the short-circuited coil under commutation