Electrical Mach...

A 400 V shunt motor has armature resistance 0.5 Ω and field resistance of 100 Ω. If the motor is delivering 10 kW at 90%. Efficiency then the value of induced emf will be – (in V)

A 220 V shunt motor with armature resistance of 0.5 Ω, runs at 500 rpm and draws 30 A at full load. The shunt field is excited to give constant main field. What will be the speed at full load if a 1 ohm resistor is placed in series with the armature circuit? 

A DC machine has total armature ampere conductors of 4500 and total flux in the machine is 0.14 wb. The torque developed in the machine is _________ (in N-m/rad)

A 4-pole dc motor is lap wound with 480 conductors. The pole shoe is 20 cm long and the average flux density over one-pole pitch is 0.4T, the armature diameter being 40 cm.

A 20 hp, 230 V, 1150 rpm dc shunt motor has 4 poles four parallel armature paths and 882 armature conductors. The armature resistance is 0.188 Ω. At rated speed and rated output, the armature current is 73 A and the field current is 1.6 A.

A 250 V shunt motor on no-load runs at 1000 rpm and takes 5 A. The total armature and shunt field resistances are respectively 0.2 Ω and 250 Ω. Calculate the speed (in rpm) when loaded and taking a current of 50 A, if armature reaction weakens the field by 3%

A 400 V DC shunt motor draws 30 amperes while supplying the rated load at a speed of 120 rad/sec. The armature resistance is 1 ohm and the field winding resistance is 250 ohms. Find the external resistance (in ohms) is inserted in series so that, the armature current should not exceed 150% of its rated value, when the motor is plugged.

A 250 V shunt motor is driving a load at 600 rpm and the armature draws a current of 20 A. What resistance should be inserted in series to the shunt field if the speed is to be raised from 600 rpm to 800 rpm? The armature resistance and shunt field resistance are 0.5 ohm and 250 ohm respectively.