Electrical Machines
It is advisable to start a DC series motor with some load to

  Limit the speed.
 Avoid sparking.
 Limit the current.
 Limit the flux.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
The synchronous reactance( Xs) is the

 reactance either due to armature reaction or leakage flux
 combined reactance due to armature reaction and leakage flux
 reactance due to leakage flux
 reactance due to armature reaction of the machine

ANSWER DOWNLOAD EXAMIANS APP