Electrical Machines Fifth harmonic component of the induced voltage in three phase AC generator can be eliminated by using a winding pitch of 5 / 6. 4 / 5. 2 / 3. 6 / 7. 5 / 6. 4 / 5. 2 / 3. 6 / 7. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements about commutating poles which are fitted on most large dc Shunt motors: 1. The commutating poles are placed in the geometric neutral plane and their number is usually Equal to the number of main poles 2. The winding on the commutating poles is connected in series with the shunt-field winding on the main poles 3. The polarity of the commutating pole must be that of the next pole further ahead 4. The commutating poles neutralize the reactance voltage produced in the coil undergoing Commutation. Of these statements, 1 and 4 are correct 2, 3 and 4 are correct 1, 2 and 3 are correct 1, 2 and 4 are correct 1 and 4 are correct 2, 3 and 4 are correct 1, 2 and 3 are correct 1, 2 and 4 are correct ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Minimum allowable resistivity of power transformer insulating oil is generally taken as 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 1 X 1012 Ω - cm at 27°C and 0.1 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In shunt dc motor the direction of rotation of the motor will reversed. When only field terminals are changed. either field terminals are reversed or armature terminals are reversed. only armature terminals are reversed. none of above. only field terminals are changed. either field terminals are reversed or armature terminals are reversed. only armature terminals are reversed. none of above. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A self-excited shunt generator fails to build up, because 1. the field circuit is open 2. The armature circuit is open 3. the residual magnetism is absent 4. The direction of rotation is wrong From these, the correct answer is 3 only 1, 3 1, 2 and 3 1, 2, 3 and 4 3 only 1, 3 1, 2 and 3 1, 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The slip of an induction motor normally does not depend on rotor speed. core loss component. shaft torque. synchronous speed. rotor speed. core loss component. shaft torque. synchronous speed. ANSWER DOWNLOAD EXAMIANS APP
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