Electrical Machines A commutator with a diameter of 50 cm rotating at 1000 rpm. For a brush width of 1.5 cm, find the time of commutation in ms. 0.512. 0.573. 0.649. 0.443. 0.512. 0.573. 0.649. 0.443. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature of a DC motor is laminated to reduce friction and windage loss. hysteresis loss. copper loss. eddy current loss. friction and windage loss. hysteresis loss. copper loss. eddy current loss. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In case of a dc motor the ratio Eb / E is indicative of efficiency. ratio of input to output voltage. ratio of starting to running torque. ratio of starting to running current. efficiency. ratio of input to output voltage. ratio of starting to running torque. ratio of starting to running current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A smaller air gap in a polyphase induction motor helps to reduce the chance of crawling. reduce the magnetizing current. reduce the chance of cogging. increase the starting torque. reduce the chance of crawling. reduce the magnetizing current. reduce the chance of cogging. increase the starting torque. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature shaft must be able to withstand bending moment due to weight of the armature. All of these twisting strains due to transmission of torque. any unbalanced magnetic pull on the armature core. bending moment due to weight of the armature. All of these twisting strains due to transmission of torque. any unbalanced magnetic pull on the armature core. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In 3 - Φ induction motor some times copper bars are placed deep in the rotor to improve starting torque. improve power factor. improve efficiency. reduce copper loss. improve starting torque. improve power factor. improve efficiency. reduce copper loss. ANSWER DOWNLOAD EXAMIANS APP
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