Electrical Machines Commutation in a DC machine may be explained as a process by which electric current in a coil is reversed. by virtue of which emf is induced in the armature conductors. in which magnetic field is set up. how alternate flux affects the main field flux. by which electric current in a coil is reversed. by virtue of which emf is induced in the armature conductors. in which magnetic field is set up. how alternate flux affects the main field flux. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The result of slip test on a 3-phase, 20 KVA, 400 V, 50 Hz connected salient pole alternator is given below- Phase value: Vmax = 100 V, Vmin = 96 V, Imax = 10 A and I min = 7 A. The direct and quadranature axis reactances are respectively 14.28 and 5.54 Ω. 14.28 and 9.60 Ω. 8.248 and 9.60 Ω. 8.248 and 5.54 Ω. 14.28 and 5.54 Ω. 14.28 and 9.60 Ω. 8.248 and 9.60 Ω. 8.248 and 5.54 Ω. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When a synchronous motor is running at synchronous speed, the damper winding produces damping torqe. eddy current torque. no torque. both 1 and 2. damping torqe. eddy current torque. no torque. both 1 and 2. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The direction of rotation of a 3 - Φ induction motor is clockwise when it is supplied with 3 - Φ sinusoidal voltage having phase sequence A - B - C. For counterclockwise rotation of motor, the phase sequence of the supply should be C - A - B. A - C - B. B - C - A or C - A - B. B - C - A. C - A - B. A - C - B. B - C - A or C - A - B. B - C - A. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is the phase difference between two windings of A.C servomotor ? 120°. 30°. 60°. 90°. 120°. 30°. 60°. 90°. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements regarding the speed control of dc motors : 1. ward-leonard method is suitable forconstant-torque drives 2. Ward-leonard method is suitable for constant-power drives 3. field-control method facilitates speed control below base speed 4. Armature-resistance control method is more efficient than ward-leanard method 5. Field-control method is suitable for constant-torque drives 6. Armature-resistance control method is suitable for constant-torque drives From these, the correct answer is 1, 4, 6 1, 3, 5 1, 2, 5 1, 2, 6 1, 4, 6 1, 3, 5 1, 2, 5 1, 2, 6 ANSWER DOWNLOAD EXAMIANS APP
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