Dr.A.P.J.Abdul Kalam University BE VII SEM ALL BRANCH Electrical Drives [EX-701] Dec - 2020 Question Paper

Dr.A.P.J.Abdul Kalam University

Bachelor of Engineering

Seventh Semester Main Examination, Dec-2020

Electrical Drives [EX-701]

Branch: EX

Time: 3:00 Hrs Max Marks 70

Note : 1. Attempt any five questions out of eight.

2. All question carry equal marks.

Q.1 a) What are electrical drives? Explain its main components.

b) Explain the operation of 1-∅ fully controlled converter fed separately excited DC

motor.

Q.1 a) Explain electric drives with its components and block diagram?

b)Explain the operation of single phase fully controlled converter fed separately excited

DC motor Drive?

Q.2 a) A 220V, 1500 rpm, 1OA separately excited dc motor with an armature resistance of

3Ω is fed from a single phase fully controlled rectifier connected to an ac source voltage

of230 V, 50 Hz. Assuming conduction, calculate the firing angle for half the motor

torque at 600 rpm.

b) Explain the speed -torque characteristics of DC motor?

Q.3 a) Explain the following Braking methods of DC motor

i) Plugging Braking ii) Dynamic Braking iii) Regenerative Braking

b) Discuss the operation of four Quadrant Chopper?

Q.4 a) Explain the two modes in which a dual converter is used to control the dc motor speed.

Which of the two methods is better and why?

b) Compare the operations of VSI and CSI?

Q.5 a) What are the Speed-Torque Characteristics of Induction Motor?

b) Write a short Note on:

1. Static Kramer Drive

2. Slip power recovery

Q.6 a) What is Static rotor resistance control?

b) Write the applications and advantages of synchronous motor drive?

Q.7 a) Discuss rotor resistance control scheme of Induction motor drive?

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b) Discuss in brief the circuit diagram for load commutated CSI fed synchronous motor?

Q.8 a) Explain variable frequency control of frequency motor?

b) Explain the operation of cycloconverter fed self controlled synchronous motor drive.

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