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    ED Assignment 2

    Uploaded by

    sushant.sahayee20
    This document contains 20 questions related to electric drives, including DC motors and induction motors. Several questions ask to calculate firing angles, duty ratios, or speeds and torques given motor parameters and operating conditions. Other questions ask to explain concepts like regenerative braking, V/F control, insertion of rotor resistance, slip power recovery, and closed loop control of induction motor drives. The final question asks to design a circuit to provide both forward and regenerative operation of a chopper-fed DC drive.

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    ED Assignment 2

    Uploaded by

    sushant.sahayee20
    10 views2 pages
    This document contains 20 questions related to electric drives, including DC motors and induction motors. Several questions ask to calculate firing angles, duty ratios, or speeds and torques given motor parameters and operating conditions. Other questions ask to explain concepts like regenerative braking, V/F control, insertion of rotor resistance, slip power recovery, and closed loop control of induction motor drives. The final question asks to design a circuit to provide both forward and regenerative operation of a chopper-fed DC drive.

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    ED assignment 2

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    This document contains 20 questions related to electric drives, including DC motors and induction motors. Several questions ask to calculate firing angles, duty ratios, or speeds and torques given motor parameters and operating conditions. Other questions ask to explain concepts like regenerative braking, V/F control, insertion of rotor resistance, slip power recovery, and closed loop control of induction motor drives. The final question asks to design a circuit to provide both forward and regenerative operation of a chopper-fed DC drive.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    10 views2 pages

    ED Assignment 2

    Uploaded by

    sushant.sahayee20
    This document contains 20 questions related to electric drives, including DC motors and induction motors. Several questions ask to calculate firing angles, duty ratios, or speeds and torques given motor parameters and operating conditions. Other questions ask to explain concepts like regenerative braking, V/F control, insertion of rotor resistance, slip power recovery, and closed loop control of induction motor drives. The final question asks to design a circuit to provide both forward and regenerative operation of a chopper-fed DC drive.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 2

    Electric Drives

    Assignment_2
    1. A 200V, 875rpm, 150A separately excited dc motor has armature resistance of 0.06 ohm. It
    is fed from a single-phase fully controlled rectifier with an ac Voltage of 220V, 50Hz.
    Assume continuous conduction, calculate:
    (a) Firing angle for rated motor torque and 750rpm
    (b) Firing angle for rated motor torque and -500rpm
    (c) Motor speed for alpha=160degree and rated torque

    2. A 220V, 1500rpm, 50A separately excited dc motor has armature resistance of 0.05 ohm. It
    is fed from a single-phase dual converter with an ac Voltage of 200V, 50Hz. Determine
    converter firing angle for
    (a) Motoring operation at rated motor torque and 1000rpm
    (b) Braking operation at rated motor torque and 1000rpm
    (c) Motoring operation at rated motor torque and -1000rpm
    (d) Braking operation at rated motor torque and -1000rpm

    3. A 220V, 1500rpm, 50A separately excited dc motor has armature resistance of 0.05 ohm. It
    is fed from a single-phase dual converter with an ac Voltage of 200V, 50Hz. Determine
    converter firing angle for
    (A) Motoring operation at 1/2rated motor torque and 1000rpm
    (B) Braking operation at 3/4rated motor torque and 1000rpm
    (C) Motoring operation at 1/2rated motor torque and -1000rpm
    (D) Braking operation at 3/4rated motor torque and -1000rpm

    4. A 220V, 750rpm, 200A separately excited dc motor has armature resistance of 0.05 ohm.
    It is fed from a three-phase dual converter with an ac Voltage of 400V, 50Hz. Determine
    converters firing angle.
    5. Explain the working of chopper control of separately excited DC motor in motoring and
    regenerative braking mode of operation and draw its speed torque characteristics.
    6. A 230V, 960rpm and 200A shunt DC motor has an armature resistance of 0.02  . The
    source has a voltage of 230V and motor is operated in dynamic braking with chopper control
    with a braking resistance of 2  .
    (i) Calculate duty ratio of chopper for a motor speed of 600rpm and braking torque equal
    to 1.5times of the rated value.
    (ii) What will be the motor speed for a duty ratio of 0.6 and motor torque equal to 1.5
    times rated torque?
    7. (a) Why is regenerative braking difficult in dc series motor? Explain.
    Or
    Explain the term dead short used in braking. What is the step used to avoid dead short.

    (b) Determine the effective value of braking resistance during dynamic braking of dc
    motor drive.
    Electric Drives
    Assignment_2
    8. Describe the working of speed control of three-phase Induction Motor usingV/f control
    and draw its speed-torque characteristics.
    9. Why is a resistance inserted in the rotor at the instant of switchover to plugging of three-
    phase Induction Motor?
    10. Draw and explain speed-torque characteristics of three-phase Induction motor using rotor
    resistance control.
    11. What is slip power recovery scheme? Explain.
    12. Differentiate between phase control and on-off control of static stator voltage control of
    three-phase Induction motor using suitable diagram.
    13. Describe the electric braking of three-phase Induction motor using suitable
    characteristics.
    14. A 440V, star-connected, three-phase, 4-pole, 50Hz, Induction Motor has Rs  R2  1
    '

    and X s  X 2  1 .For regenerative braking determine maximum overhauling torque it


    '

    can hold and range of speed for safe operation.


    15. Write short notes on closed loop control of Induction motor drive.
    16. Write short notes on braking DC motor and Induction motor drive.
    17. While operating in practical application of chopper fed DC drive there is requirement of
    motoring and braking both operation. Design and explain a circuit which can give
    forward motoring and regenerative both operation.
    18. What are the advantages of electric braking over mechanical braking?
    19. Explain the stator voltage control of three-phase Induction Motor. What is the concept of
    soft start associate with it?
    20. Write shorts note on frequency control of three-phase IM drive.

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