Electrical Machines What is the frequency of a alternator, if P = number of poles and N = revolution made per second? PN / 2 Hz. 120 / PN Hz. 120N / P Hz. 120P / N Hz. PN / 2 Hz. 120 / PN Hz. 120N / P Hz. 120P / N Hz. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The air gap between the yoke and armature is dc machine is kept very small to avoid over heating. to achieve a stronger magnetic field. to avoid locking of the armature. All of these to avoid over heating. to achieve a stronger magnetic field. to avoid locking of the armature. All of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A transformer has hysteresis loss of 30 W, at 240 V, 60 Hz. The hysteresis loss at 200 V, 50 Hz will be 36 W. 28 W. 30 W. 25 W. 36 W. 28 W. 30 W. 25 W. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is the necessity of copper brushes in a dc motors? None of these. To increase the flux cutting by the rotor. To absorb the mechanical shocks produced during running condition. To convert alternating supply current to direct current. None of these. To increase the flux cutting by the rotor. To absorb the mechanical shocks produced during running condition. To convert alternating supply current to direct current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For higher values of armature, the speed of a DC series motor is Proportional to armature current. Constant. Inversely proportional to armature current. Proportional to the square of armature current. Proportional to armature current. Constant. Inversely proportional to armature current. Proportional to the square of armature current. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC Shunt Motor having shunt field resistance of 250 Ω and armature resistance of 0.5 Ω is connected to 250 V supply and load current of 21 A. What is the back emf generated ? 240 V. 150 V. 210 V 230 V. 240 V. 150 V. 210 V 230 V. ANSWER DOWNLOAD EXAMIANS APP
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