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 A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.125 p.u 0.75 p.u 0.25 p.u 0.5 p.u 0.125 p.u 0.75 p.u 0.25 p.u 0.5 p.u 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, 2, 3 and 4 are correct 1 and 4 are correct 1, 2 and 4 are correct 1, 2 and 3 are correct 2, 3 and 4 are correct 1 and 4 are correct 1, 2 and 4 are correct 1, 2 and 3 are correct ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A Shunt generator running at 1000 rpm has generated emf of 100 V. If the speed increases to 1200 rpm, the generated emf will be nearly 175 V 120 V 240 V 140 V 175 V 120 V 240 V 140 V ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines During hunting of a synchronous motor harmonic are developed in the armature circuit. damper bar develops torque. field excitation increases. negative phase sequence currents are generated. harmonic are developed in the armature circuit. damper bar develops torque. field excitation increases. negative phase sequence currents are generated. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Which of the following represents the pitch factor? Cos α sin (α/2) Cos (α/2) Cos α² Cos α sin (α/2) Cos (α/2) Cos α² ANSWER DOWNLOAD EXAMIANS APP
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