In a A.C. series motor armature coils are usually connected to commutator through resistance.
Answer : A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.
Answer : If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.
Description : The function of a brush and commutator arrangement in a dc motor is to (1) produce unidirectional torque (2) produce unidirectional current in the armature (3) help in changing the direction of rotation of the armature (4) reduce sparking
Answer : The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque
Answer : Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.
Answer : In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to 25% of the previous value.