JNTU B.Tech III ELECTRICAL MACHINE DESIGN Previous Question Paper (January/February - 2023 - R18)

What is space factor in machine design?

What is the need of thermal considerations in machine design?

What are the major causes of temperature rise in transformers?

For a power transformer operating at full load it draws voltage and current equal to 200 V and 100 A respectively at 0.8 pf. Iron and copper losses are equal to 120 kW and 300kW. What is efficiency?

If all the stator coils of an induction motor are connected for the same magnetic polarity, what will happen to rotor pole polarity?

Why blades are provided to the squirrel cage induction motors?

In synchronous machines, short circuit ratio indicates what?

A 6 kVA, 220 V, 3 phase, star connected synchronous generator has a winding resistance of 0.15 ohm per phase and synchronous reactance of 6.1 ohm per phase. Find the voltage regulation of alternator at a load power factor of 0.8 lagging.

What are design optimization methods used in Computer Aided Machine Design?

Write some applications of claw-pole machines.

What are the important design factors to be considered in machine design? Explain.

Discuss about the choice of specific electrical and magnetic loadings of machines.

Explain about the different basic principles used in the design of electrical machines.

What are drawbacks of temperature rise in machines?

Give the detailed comparison of power and distribution transformers.

Calculate approximate overall dimensions for a 200 kVA, 6600/440 V, 50 Hz, 3 phase core type transformers. The following data may be assumed: EMF per turn = 9V; maximum flux density = 1 Wb/m2; current density = 2 A/mm2; window space factor = 0.3, overall height = overall width; stacking factor = 0.9; Use a 3 stepped core. For a three stepped core: Width of largest stamping= 0.9 d and Net iron area = 0.6d2, where d is the diameter of the circumscribing circle.

Explain in detail about the core design of the transformers.

Show that the output of a 3-phase core type transformer is:

Explain in detail about different factors that should be considered while designing the rotor slots of squirrel cage rotor.

A 3 phase, 2 pole, 50 Hz squirrel cage induction motor has a rotor diameter 0.17 m and core length 0.1 m. The peak density in the air gap is 0.45 Wb/m2. The rotor has 33 bars, each of resistance 110 μΩ and a leakage inductance 2 μH. The slip is 5%. Calculate the rotor output and torque exerted. Neglect the resistance of end rings.

Explain in detail about the stator design of three phase induction machine.

Estimate the stator core dimensions and number of stator conductors for a 100 kW, 3300 V, 50 Hz, 12 pole star connected slip ring induction motor. Average gap density = 0.45 Wb/m2, ampere conductors per meter = 25000, efficiency = 0.89, power factor = 0.9 and winding factor = 0.95. The slot loading should not exceed 500 ampere conductors.

Write about the limitations of traditional designs need for CAD analysis.

Discuss about complex structures of Permanent Magnet Synchronous Machines.