Ques. Does the added resistance of preventive leads, or high resistance brushes, materially reduce the efficiency of the machine?
Ans. Not to any great extent, because it is very small in comparison with the resistance of the whole armature winding.
Fig. 1,885.—Section of ring armature of commutator motor showing local current set up by transformer action of the alternating flux.
Ques. What is the objection to reducing the number of turns of the short circuited coils to diminish the tendency to sparking?
Ans. The cost of the additional number of commutator bars and connectors as well as the added mechanism.
Ques. What effect has the inductance of the field and armature on the power factor?
Ans. It produces phase difference between the current and impressed pressure resulting in a low power factor.
Ques. What is the effect of this low power factor?
Ans. The regulation and efficiency of the system is impaired.