Electrical Engineering: Electrical Machine MCQ

A 50 Hz, power system network is operated under load of 100 MW. When the load is increases, the power input by the synchronous generator is increases by 10 MW and frequency of the rpm fall to 49.75 Hz. What will be the load at power system for the frequency falls to 49.25 Hz?

A 250 DC shunt motor having armature resistance of 0.2 Ω and field resistance of 100 Ω. It draws a no load current of 5 A at 1200 rpm. The brush drop is 1 V per brush at all operating conditions. If motor draws 50 A at fulled load and flux per pole is decreased by 5% because of armature reaction. The speed of the motor at full load is ____ rpm.

A synchronous generator has lossless reactance Xs . Then V_A is terminal voltage and E_f  is internal emf voltage.
P : If power factor is leading then always V_A > E_f
Q : If power factor is lagging then always V_A < E_f
Which of the statement is true?

A 3-φ, 50 Hz, 4 pole induction motor runs at no load with a slip of 1%, at full load the motor runs at a slip of 5%. The percentage speed regulation of the motor is _____.

4 kVA, 200/100 V, 50 Hz single phase transformer has no load core loss of 450 W. If  high voltage side is energized by 160 V, 40 Hz, the core loss will be 320 W. Find the core loss if the high voltage side is energized by 100 V, 25 Hz.