What modifications have to be done on DC series motor to make it to work with single phase AC supply?

Modifications on DC series motor to make it to work with single phase AC supply:

1. The entire magnetic circuit is laminated in order to reduce the eddy current loss. Hence an AC series motor requires a more expensive construction than a DC series motor. 
2. The series field winding uses as few turns as possible to reduce the reactance of the field winding to a minimum. This reduces the voltage drop across the field winding. 
3. A high field flux is obtained by using a low-reluctance magnetic circuit.
4. There is considerable sparking between the brushes and the commutator when  the motor is used on AC supply. It is because the alternating flux stablishes high currents in the coils short-circuited by the brushes. When the shortcircuited coils break contact from the commutator, excessive sparking is produced. This can be eliminated by using high-resistance leads to connect the coils to the commutator segments. 

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