Electrical Machines The mechanical power is developed by a DC motor is maximum when back emf is equal to twice of applied voltage. back emf is equal to applied voltage. back emf is equal to half of applied voltage. none of above. back emf is equal to twice of applied voltage. back emf is equal to applied voltage. back emf is equal to half of applied voltage. none of above. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements : 1. interpole windings are connected in series with armature windings 2. polarity of interpoles must be the same as that of the main poles in advance 3. distortion of the main field under the pole shoes is not affected by the use of interpoles From above, the correct answer is 1 and 3 1 alone 1 and 2 2 and 3 1 and 3 1 alone 1 and 2 2 and 3 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Conservator tank is used None of these for better cooling of transformer. to act as an oil storage. to take up the expansion of oil due to temperature rise. None of these for better cooling of transformer. to act as an oil storage. to take up the expansion of oil due to temperature rise. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 240 V dc series motor takes 40 A when giving its rated output at 1500 rpm. Its resistance is 0.3 Ω. The value of resistance which must be added to obtain rated torque at 1000 rpm is 1.9 Ω 5.7 Ω 2.2 Ω 6 Ω 1.9 Ω 5.7 Ω 2.2 Ω 6 Ω ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 500 V, 120 KW, 50 Hz, star connected synchronous motor operating at 0.8 power factor leading has full load efficiency of 91%. The armature resistance is equal to 0.08Ω. The magnitude of armature current is nearly equal to 190 A. 240 A. 127 A. 173 A. 190 A. 240 A. 127 A. 173 A. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A voltmeter gives 120 oscillations per minute when connected to the rotor of an induction motor. The frequency is 50Hz. The slip of the motor is 2% 5% 25% 4% 2% 5% 25% 4% ANSWER DOWNLOAD EXAMIANS APP
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