Electrical Machines When a short circuit test on a transformer is performed at 25 V, 50 Hz, the drawn current is I1. If the test is performed by 25 V and 25 Hz and power drawn current is I2, then I1 > I2 I1 < I2 None of these I1 = I2 I1 > I2 I1 < I2 None of these I1 = I2 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The speed regulation of a DC motor is given as (NnL − NfL)/NfL. (NfL − NnL)/NnL. NnL − NfL. NnL/NfL. (NnL − NfL)/NfL. (NfL − NnL)/NnL. NnL − NfL. NnL/NfL. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If starter is not used with large DC motor for starting, it will all of above. provide execessive voltage drop in line. draw a starting current many times its rated full load current. damage the armature and commutator. all of above. provide execessive voltage drop in line. draw a starting current many times its rated full load current. damage the armature and commutator. 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 3 are correct 1, 2 and 4 are correct 1 and 4 are correct 2, 3 and 4 are correct 1, 2 and 3 are correct 1, 2 and 4 are correct 1 and 4 are correct 2, 3 and 4 are correct ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The speed of a 50 Hz three phase induction motor under full load condition is 725 rpm the number of poles of the motor are ______________. 6. 2. 4. 8. 6. 2. 4. 8. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A transformer has maximum efficiency at 3/4 load. The ratio of iron loss and full load copper loss is 9/16. 16/9. 4/3. 3/4. 9/16. 16/9. 4/3. 3/4. ANSWER DOWNLOAD EXAMIANS APP
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