a) Explain the effects of armature reaction in a dc motor and draw a vector dia

a) Explain the effects of armature reaction in a dc motor and draw a vector diagram of the field and armature mmfs. What steps can be taken in the motor design to counteract the effects of armature reaction? [6 marks]
The nameplate details of a shunt wound dc motor are as follows:
30kW 200V 205A 1700 rev/min
The shunt field resistance is 240 ohms and the total resistance of the armature circuit is 0.15 ohms. The motor is fitted with compensating and interpole windings.
b) Calculate the no-load current of the motor. [7 marks]
c) Calculate the no-load speed. [3 marks]
d) If the motor is to deliver full load torque at 1200 rev/min what value of resistance must be connected in series with the armature to achieve this? [4 marks]
Question 2
A three phase delta connected 400V induction motor runs at a full load slip of 4% when drawing a line current of 50A at 0.86 power factor from the supply. When running on no-load at full voltage the motor draws a line current of 15A and 2kW of power including 650W of friction windage and rotor iron loss from the three phase main. The phase resistance of the stator winding is 0.5 ohms. Calculate the full load power output and efficiency of the motor. [12 marks]