Electrical Machines Which of the following machine is invariably provided with forced ventilation? Hermetically sealed motor of refrigerator. 50 MW generator in a power plant. Fractional horse power high speed motor. Fractional horse power slow speed motor. Hermetically sealed motor of refrigerator. 50 MW generator in a power plant. Fractional horse power high speed motor. Fractional horse power slow speed motor. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The frequency of voltage generated by an alternator having 8 poles and rotating at 250 rpm is 16.67 Hz. 25 Hz. 60 Hz. 50 Hz. 16.67 Hz. 25 Hz. 60 Hz. 50 Hz. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For the purpose of starting an induction motor, star/delta switch is an equivalent to auto transformer of ratio 57.7% 66.3% 50% 33.3% 57.7% 66.3% 50% 33.3% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The change in speed of a DC generator due to increased load is corrected by increasing terminal voltage. increasing input power of the prime mover. increasing armature cooling. increasing armature resistance. increasing terminal voltage. increasing input power of the prime mover. increasing armature cooling. increasing armature resistance. 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, 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 2, 3 and 4 are correct 1 and 4 are correct ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 250 volt dc series motor having an armature resistance of 0.2 Ω takes a load current of 60 A. What will be the torque produced at the shaft of the motor? Consider brush drop of 1V. 266.20 N-m. 133.22 N-m 234.76 N-m. can not be determined. 266.20 N-m. 133.22 N-m 234.76 N-m. can not be determined. ANSWER DOWNLOAD EXAMIANS APP
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