Review Master Electrician (Part 2) Questions and Answers 100% Correct

The ordinary direct current series motor does not operate satisfactorily with alternating current. One of the main reasons for this is a. excessive heating due to eddy currents in the solid parts of the field structure b. that the armature current and field current are out of phase with each other c. that the field flux lags 120 in time phase with respect to the line voltage d. excessive heating due to the low voltage drop in the series field - ANSWER-a. excessive heating due to eddy currents in the solid parts of the field structure A DC elevator motor, on a gearless traction machine, has a series field for compounding during the acceleration period. This field is cut out when the motor has reached full speed, for the purpose of a. preventing excessive heat b. reducing the line current c. providing constant speed over a wide range of load conditions d. saving the cost of losses in the series field - ANSWER-c. providing constant speed over a wide range of load conditions The protective device for a motor branch circuit