A 600 V DC motor drives a 60 kW at 900 rpm. The shunt field resistance is 100 $\Omega$ and the armature resistance is 0.16$\Omega$. If the efficiency is 85% then the speed regulation of motor is _________%.

1. 3.1

Q. A 60 kW, 250 V shunt motor takes 16 A when running at 1440 rpm. The resistance of the armature and field are 0.2 $\Omega$ and 125 $\Omega$ respectively. The efficiency of the motor when taking 152 A is

Q. A 20 kW, 300 V dc shunt motor is driving a constant torque load with line current of 100 A at a speed of 1600 rpm. Motor has armature and field winding resistance as 0.02 $\Omega$ and 100 $\Omega$ respectively. If 50 $\Omega$ external resistance is added in field circuit, then motor is running at (Assume linear magnetzation curve)

Q. A 230 V, 1800 rpm, long shunt, cumulative compound motor has a shunt field resistance of 460 $\Omega$, series field resistance of 0.2 $\Omega$ and armature circuit resistance of 1.3 $\Omega$. The full-load line current is 10.5 A. The rotational loss is 5% of the power developed. Then the efficiency (in percentage) of the motor at full load is________.

Q. A 230 V, 250 rpm, 100 A separately-excited dc motor has an armature resistance of 0.5 $\Omega$. The motor is connected to 230 V dc supply and rated dc voltage applied to the field winding. It is driving a load whose torque-speed characteristic is given by $T_L=500-10\omega$. The steady state speed at which the motor will drive the load is

Q. A 200 V, 1000 rpm dc shunt motor drives a load that requires a constant torque regardless of the speed of operation. The armature circuit resistance is 0.03$\Omega$. When this motor takes armature current of 75A. If the flux is reduced to 75% of its original value, then new speed will be ______ rpm.