Fig. 1,887.—Diagram of single phase series commutator motor. It is practically the same as the series direct current motor, with the exception that all the metal of the magnetic circuit must be laminated.
Ques. What are the characteristics of the series motor?
Ans. They are similar to the direct current series motor, the torque being a maximum at starting and decreasing as the speed increases.
Ques. For what service is the series motor especially suited?
Ans. On account of its powerful starting torque it is particularly desirable for traction service.
Neutralized Series Motor.—A chief defect of the series motor is the excessive self-induction of the armature, hence in almost every modern single phase series motor a neutralizing coil is employed to diminish the armature self-induction.
The neutralizing coil is wound upon the frame 90 magnetic degrees or half a pole pitch from the field winding and arranged to carry a current equal in magnetic pressure and opposite in phase to the current in the armature.
