Electrical Drives (EX-801) - Important Questions

Draw the block diagram of electrical drives and explain the function of each block, including the power converters.

Explain steady-state / mechanical stability of an electric drive and why it depends on the relative motor and load torque-speed characteristics.

Explain constant torque and constant power drives with suitable speed-torque characteristics and examples.

Explain with neat circuit diagram the principle and working of chopper control of a separately excited DC motor.

Explain the different types of braking employed in DC motors.

Explain V/f control of three-phase induction motor with diagram, including why V/f is kept constant below base speed and voltage is kept constant above base speed, and range of speed control.

Explain the conventional / static Scherbius system/drive for speed control of slip-ring induction motor with neat diagram.

Describe the static Kramer drive for speed control of the induction motor with neat diagram and power flow.

A 3-phase squirrel-cage induction motor driving a fan load has its speed reduced by stator voltage control. For given rated voltage, current and speed, find the terminal voltage, stator current and developed torque at reduced speed assuming torque proportional to square of speed.

Explain the working of VSI-fed synchronous motor drive with block diagram for closed-loop operation.

Describe speed control of self-controlled synchronous motor drives with block diagram.

Explain the construction, principle of working and fundamentals of switched reluctance motor with neat diagram.

Explain digital control of electric drives with a neat block diagram.

Explain the working principle, construction and operation of Permanent Magnet Synchronous Motor (PMSM).

Write short notes on any two of the following: (a) Load-drive speed-torque characteristics and quadrant operation (b) Load equalization with flywheel (c) Rating and selection of electric drives.