Electrical Machines A commutator in DC machines can 1. provide half-wave rectification 2. Provide full-wave rectification 3. convert ac to dc 4. Convert dc to ac 5. provide controlled full-wave rectification From these, the correct answer is 2, 3, 4, 5 1, 2, 3 2, 3 ,5 2, 3, 4 2, 3, 4, 5 1, 2, 3 2, 3 ,5 2, 3, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The results of a slip test for determining direct axis (Xd) and quadrature axis (Xq) reactances of a star connected salient pole alternator are given below Phase values: Vmax = 108 V ; Vmin = 96 V Imax = 12 A ; Imin = 10 A Hence the two reactances will be Xd = 9Ω and Xq = 9.6Ω Xd = 8Ω and Xq = 10.8Ω Xd = 10.8Ω and Xq = 8Ω Xd = 9.6Ω and Xq = 9Ω Xd = 9Ω and Xq = 9.6Ω Xd = 8Ω and Xq = 10.8Ω Xd = 10.8Ω and Xq = 8Ω Xd = 9.6Ω and Xq = 9Ω ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a DC generator the emf generated by the armature is maximum when induced voltage is high. shaft rotation is high. rate of change of flux is maximum. rate of change of flux is minimum. induced voltage is high. shaft rotation is high. rate of change of flux is maximum. rate of change of flux is minimum. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If B is flux density, l the length of the conductor and v the velocity of the conductor, then emf is given by Blv2. Blv. Bl2v2. Bl2v. Blv2. Blv. Bl2v2. Bl2v. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For a given torque, reducing diverter resistance of a DC series motor causes increase in speed demanding more armature current. decrease in speed but armature current remains the same. increase in speed but armature currnet remains the same. decrease in speed demanding less armature current. increase in speed demanding more armature current. decrease in speed but armature current remains the same. increase in speed but armature currnet remains the same. decrease in speed demanding less armature current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop DC motor torque. induction generator torque. induction motor torque. synchronous motor torque. DC motor torque. induction generator torque. induction motor torque. synchronous motor torque. ANSWER DOWNLOAD EXAMIANS APP
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