Electrical Machines If the armature electric current is increased to double its previous value, and the time of commutation is halved, how will the reactance voltage vary? It will be halved. It will be doubled. It will remain the same. It will becomes four times. It will be halved. It will be doubled. It will remain the same. It will becomes four times. 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 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 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 4 X 1012 Ω - cm at 27°C and 0.4 X 1012 2 X 1012 Ω - cm at 27°C and 0.2 X 1012 3 X 1012 Ω - cm at 27°C and 0.3 X 1012 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 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 1, 2 and 3 1, 3 3 only 1, 2, 3 and 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In DC generators, electric current to the external circuit from armature is given through commutator. none of above. slip rings. solid connection. commutator. none of above. slip rings. solid connection. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In case of 3 - Φ IM, plugging means starting the motor on load which is more than the rated load. pulling the motor directly on line without a rotor. interchanging two supply phases for quick stopping. locking of rotor due to harmonics. starting the motor on load which is more than the rated load. pulling the motor directly on line without a rotor. interchanging two supply phases for quick stopping. locking of rotor due to harmonics. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following represents the commutator pitch? Number of conductors spanned by one coil at the back end of the armature. Number of commutator segments between two successive coils. Number of conductors spanned by one coil at the front end of the armature. The distance between the staring of first coil and its next successive coil Number of conductors spanned by one coil at the back end of the armature. Number of commutator segments between two successive coils. Number of conductors spanned by one coil at the front end of the armature. The distance between the staring of first coil and its next successive coil ANSWER DOWNLOAD EXAMIANS APP
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