Electrical Machines The direction of rotation of a 3 - Φ induction motor can be reversed by transposing any two leads from slip rings. transposing any two leads from supply. disconnecting any one phase. transposing all the three leads from the supply. transposing any two leads from slip rings. transposing any two leads from supply. disconnecting any one phase. transposing all the three leads from the supply. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a dc machine 72 number of coils are used. Find the number of commutator segments required? 72 37 36 74 72 37 36 74 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a synchronous machine, if φ is the flux per pole and f is the frequency of the emf induced E then E ∝ f/φ E ∝ φ/f E ∝ φf E ∝ 1/(φf) E ∝ f/φ E ∝ φ/f E ∝ φf E ∝ 1/(φf) ANSWER DOWNLOAD EXAMIANS APP
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 becomes four times. 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. 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 4 2, 3 and 4 1, 2, and 3 1 and 3 1, 2 and 4 2, 3 and 4 1, 2, and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The stator frame in an induction motor is used to ventilate the armature. hold armature stamping in position. protect the whole machine. provide return path for the flux. ventilate the armature. hold armature stamping in position. protect the whole machine. provide return path for the flux. ANSWER DOWNLOAD EXAMIANS APP
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