Siddaganga institute of technology, tumkur dept. Of electrical and electronics engineering

SIDDAGANGA INSTITUTE OF TECHNOLOGY, TUMKUR

DEPT. OF ELECTRICAL AND ELECTRONICS ENGINEERING

Subject: Basics of Electrical Engineering (BEL) Tutorials on DC Motors

1. 
   A 500V dc shunt motor has 4 poles and wave connected winding with 492 conductors., the flux per pole is 0. 05wb.The full load current is 20 A. The armature and shunt field resistances are 0.1 and 250D respectively. Calculate the speed and developed torque.
   

2. 
   A 4 pole,220V, lap connected dc shunt motor has 36 slots with each slot containing 16 conductors. The line current is 40A. The field resistance and armature resistances are 110ohm and 0.1ohm respectively. The motor develops an output power of 6 KW. The flux per pole is 40 mwb. Calculate a) The Speed b) Torque developed by armature c) the shaft torque.
   

3. 
   The field current in a dc shunt motor is 2A and the line current is 20A at 200V. calculate the back emf and the torque developed when speed is 1500 rpm.
   

4. 
   A 440V dc shunt motor takes an armature current of 20A and runs at 500 rpm. The armature resistance is 0.6£2. If the flux is reduced by 30 % and torque is increased by 40 %, what are the new values of armature current and the speed.
   

5. 
   A 200 V series motor has resistance (Ra+ Rse) of 0.2 ohm and runs at 1000 rpm. The full load current drawn from supply is 50 A. Calculate speed of motor at which it develops half of full load torque.
   

6. 
   A dc series motor runs at a speed of l000 rpm when taking a current of 22A from the supply. If the load is changed such that the current drawn by the motor is increased to 55 A, Calculate the speed of the motor new load. The armature: and series winding resistances are 0.3 and 0.4 respectively. Assume the supply voltage to be 250 V
   

7. 
   A 6 pole 250V dc series motor is wave connected. There are 250 slots, each having 4 conductors. The fiuk per pole is 1.75mWb when the motor is taking 80A. The field resistance is 0.05ohm and armature resistance is 0.1Q. Calculate the speed of the motor.
   

8. 
   The armature of shunt motor has a lap winding accommodated in 60 slots, each containing 20 conductors. If the useful flux per pole is 28 mWb, calculate the total torque developed in N-m when the armature current is 50A.
   

9. 
   A 4 pole, lap wound, 220V DC shunt motor has an armature resistance of 0.4 ohm. and shunt field resistance of 220 ohm. It is running at 1500 rpm, when it is taking 40A from supply. Find the speed of the motor when the motor is taking 10A from supply.
   

10. 
    A 220V DC shunt motor runs at 500 rpm taking an armature current of 50A. Find the speed if the torque is doubled. Armature resistance is 0.2 ohm.