Electrical Machine - II — Summer 2019

Explain the Parallel operation of 3-phase transformer.

Discuss different methods of speed control of 3–phase Induction motor.

Explain cogging effect and crawling effect in detail.

Explain the polarity test in 3-phase Transformer.

Why we require starters for 3- phase induction motors? Explain Auto- transformer starter with necessary circuit diagram.

Describe the construction and working of a double-cage induction motor.

Explain principle, advantages and applications of Linear Induction Motor.

Why a 1-phase induction motor is not self starting? Explain the starting methods for single phase induction motor in brief.

Explain Scott connection for transformer with diagram.

Discuss the doubly fed induction motor with its advantages and disadvantages.

Explain the Sumpner’s test in 3-phase transformer.

Asquirrel cage induction motor when started by means of a star-delta starter takes 180% of full load line current and develops 35% of full load torque at starting. Calculate the starting torque and current in terms of full load values, if an auto transformer with 75% tappings were employed.

Discuss the construction, working principle and applications of shaded pole induction motor.

Explain working principle, construction of Repulsion motor.

Explain construction of welding transformer. How does it differ from power transformer?

Explain working principle and construction of scharge motor.

Explain the construction, working principle and applications of induction generator.