Electrical Machines Which of the following DC Motor uses 4-point starter? DC shunt motor with field weaking control. DC shunt motor with armature resistance. DC series motor. DC compound motor. DC shunt motor with field weaking control. DC shunt motor with armature resistance. DC series motor. DC compound motor. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following transformer insulating oil generally used in India? Olefin based insulating oil. Naphtha based insulating oil. Aromatics based insulating oil. Paraffin based insulating oil. Olefin based insulating oil. Naphtha based insulating oil. Aromatics based insulating oil. Paraffin based insulating oil. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements : 1. interpole windings are connected in series with armature windings 2. polarity of interpoles must be the same as that of the main poles in advance 3. distortion of the main field under the pole shoes is not affected by the use of interpoles From above, the correct answer is 2 and 3 1 and 3 1 and 2 1 alone 2 and 3 1 and 3 1 and 2 1 alone ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc shunt motor runs at a no-load speed of 1140 rpm. At full load, armature reaction weakens the main flux by 5% whereas the armature circuit voltage drops by 10%. The motor full-load speed in rpm is 1200 1080 1000 1203 1200 1080 1000 1203 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A three phase 400 V, 6 pole, 50 Hz, squirrel cage induction motor is running at a slip of 5%. The speed of stator magnetic field with respect to rotor magnetic field and speed of rotor w.r.t stator magnetic field are zero , - 50 rpm. 1000 rpm, - 50 rpm. zero, 950 rpm. 1000 rpm, 950 rpm. zero , - 50 rpm. 1000 rpm, - 50 rpm. zero, 950 rpm. 1000 rpm, 950 rpm. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following factors improve commutation in a dc machine ? 1. High contact resistance of brushes 2. High inductance of the coils undergoing commutation 3. Shifting of brushes in the direction of rotation for a generator and in the opposite direction For a motor 4. Narrow width for the commutation bars Select the correct answer using the codes given below : Codes : 1 and 3 1, 2, and 3 2, 3 and 4 1, 2 and 4 1 and 3 1, 2, and 3 2, 3 and 4 1, 2 and 4 ANSWER DOWNLOAD EXAMIANS APP
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