GATE EE 2022: Electrical Machines Quiz 21

When two generators are operating together, an increase in governor set points on one of them:

1) Decrease the supply frequency

2) Increase in Power supply by that generator, while reducing the power supplied by the other one.

Which of the above statements is/are correct?

Consider the following statements regarding commutation in DC machines:

1) In a dc machine the ripples in emf generated are reduced by employing commutator with large number of segments.

2) In dc machine the number of commutator segments is equal to armature turns.

3) The purpose of commutator in dc generator is to convert dc into ac.

Which of the above statements is/are NOT correct?

A 3-ϕ 50 Hz, 8 pole, star connected alternator has 120 stator slots and each slot has 10 conductors. If the coil span is 12 slots, then the value of pitch factor will be-

A 3-ϕ, 14.5 kW, 400V, four pole, 60 Hz, IM delivers full output power to a load connected to its shaft and running at speed of 1728 rpm. The windage and friction loss of the motor is 500 W. The value of rotor copper loss of motor will be-

For the magnetic circuit shown below the specification are given as follows:

Number of turns: 200

Length of core: 256 cm

Area of cross section: 32 cm²

Relative permeability: 3200

The magnetic energy stored in the circuit will be____π mJ

The slip at which maximum Power developed for 3-phase IM, If 120V, 60 Hz, 6-Pole, (Δ) 3 phase IM has stator impedance = (0.1 + j0.15) Ω/phase and rotor impedance = (0.1 + j0.25) Ω/phase (at standstill).