Electrical Machines When the armature current of 5 Amp is flowing through the dc motor the torque produced is 47 Nm. Keeping the speed constant if the armature current is increased to 7 amp, calculate the new torque. Assume losses to be constant. 65.8 Nm. 27.73 Nm . 74 Nm. 38.5 Nm. 65.8 Nm. 27.73 Nm . 74 Nm. 38.5 Nm. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Slip speed is the difference of synchronous speed and actual rotor speed. sum of synchronous and rotor speeds. difference of actual rotor speed and synchronous speed. half of the sum of synchronous and rotor speeds. difference of synchronous speed and actual rotor speed. sum of synchronous and rotor speeds. difference of actual rotor speed and synchronous speed. half of the sum of synchronous and rotor speeds. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is the increase in the torque expressed as percentage of initial torque, if current drawn by the dc series motor is increased from 10A to 11A? 11% 21% 10% 41% 11% 21% 10% 41% ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Consider the following statements regarding the speed control of dc motors : 1. ward-leonard method is suitable forconstant-torque drives 2. Ward-leonard method is suitable for constant-power drives 3. field-control method facilitates speed control below base speed 4. Armature-resistance control method is more efficient than ward-leanard method 5. Field-control method is suitable for constant-torque drives 6. Armature-resistance control method is suitable for constant-torque drives From these, the correct answer is 1, 2, 6 1, 2, 5 1, 3, 5 1, 4, 6 1, 2, 6 1, 2, 5 1, 3, 5 1, 4, 6 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A simple method of increasing the voltage of a DC generator is to increase the number of turns in armature coil. increase the source frequency. increase the speed of shaft rotation. increase the number of turns in field coil. increase the number of turns in armature coil. increase the source frequency. increase the speed of shaft rotation. increase the number of turns in field coil. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is 15.1 Ω 31.9 Ω 15.9 Ω 31.1 Ω 15.1 Ω 31.9 Ω 15.9 Ω 31.1 Ω ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS