A 250 V dc shunt machine has armature circuit resistance of 0.6 $$\Omega$$ and field circuit resistance of 125 $$\Omega$$. The machine is connected to 250 V supply mains. The motor is operated as a generator and then as a motor separately. The line current of the machine in both the cases is 50 A. The ratio of the speed as a generator to the speed as a motor is ____________.

Assuming an ideal transformer, The Thevenin's equivalent voltage and impedance as seen from the terminals x and y for the circuit in figure are

A single phase, 50 kVA, 1000 V/100 V two winding transformer is connected as an autotransformer as shown in the figure. The kVA rating of the autotransformer is _________.

In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?