GATE EE 2018 EXAM:Electrical Machines Quiz 12

A 4–pole, 3–phase, double layer winding is housed in a 36–slot stator for an ac machine with 60 ° phase spread. Coil span is 7 slot pitches. Number of slots in which top and bottom layers belong to different phases is

A field excitation of 20 A in a certain alternator results in an armature current of 400 A in short circuit and a terminal voltage of 2000 V on open circuit. The magnitude of the internal voltage drop within the machine at a load current of 200 A is

A stand–alone engine driven Synchronous generator is feeding a partly inductive load. A capacitor is now connected across the load to completely nullify the inductive current. For this operating condition

In a cross-sectional view of two-pole, salient-rotor, three-phase synchronous machine as shown, the Park’s transformation is applied to:

Two 3-phase, Y-connected alternators are to be paralleled to a set of common bus bars. The armature has a per phase synchronous reactance of 1.7 Ω and negligible armature resistance. The line voltage of the first machines is adjusted to 3300 V and that of the second machine is adjusted to 3200 V, the machine voltages are in phase at the instant they are paralleled. Under this condition, the synchronizing current per phase will be

and are steady state d-axis synchronous reactance, transient d-axis reactance and sub-transient d-axis reactance of a synchronous machine respectively. Which of the following statements is true?

A 400V, 50 kVA, 0.8 pf leading Δ-connected, 50 Hz synchronous machine has a synchronous reactance of 2Ω and negligible armature resistance. The friction and wind age losses are 2 kW and the core loss is 0.8 kW. The shaft is supplying 9kW load at a power factor of 0.8 leading. The line current drawn is