Nothing Special   »   [go: up one dir, main page]
Scribd Logo
Upload

Welcome to Scribd!

  • 15 views

    Gujarat Technological University: Instructions

    Uploaded by

    wikaja9419
    This document is an exam for a course on Electrical Machines and Electronics. It contains 5 questions testing students' knowledge on topics like the working principles of DC generators and alternators, speed control methods for DC motors, how rotating magnetic fields are produced in three-phase induction motors, types of instrument transformers, rectifiers, AC and DC transmission, Boolean laws, and electrical tariffs. The exam has a total of 70 marks and students are instructed to attempt all questions within the time allotted.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd

    Gujarat Technological University: Instructions

    Uploaded by

    wikaja9419
    15 views1 page
    This document is an exam for a course on Electrical Machines and Electronics. It contains 5 questions testing students' knowledge on topics like the working principles of DC generators and alternators, speed control methods for DC motors, how rotating magnetic fields are produced in three-phase induction motors, types of instrument transformers, rectifiers, AC and DC transmission, Boolean laws, and electrical tariffs. The exam has a total of 70 marks and students are instructed to attempt all questions within the time allotted.

    Original Description:

    Original Title

    131901

    Copyright

    © © All Rights Reserved

    Available Formats

    PDF, TXT or read online from Scribd

    Did you find this document useful?

    Is this content inappropriate?

    This document is an exam for a course on Electrical Machines and Electronics. It contains 5 questions testing students' knowledge on topics like the working principles of DC generators and alternators, speed control methods for DC motors, how rotating magnetic fields are produced in three-phase induction motors, types of instrument transformers, rectifiers, AC and DC transmission, Boolean laws, and electrical tariffs. The exam has a total of 70 marks and students are instructed to attempt all questions within the time allotted.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    15 views1 page

    Gujarat Technological University: Instructions

    Uploaded by

    wikaja9419
    This document is an exam for a course on Electrical Machines and Electronics. It contains 5 questions testing students' knowledge on topics like the working principles of DC generators and alternators, speed control methods for DC motors, how rotating magnetic fields are produced in three-phase induction motors, types of instrument transformers, rectifiers, AC and DC transmission, Boolean laws, and electrical tariffs. The exam has a total of 70 marks and students are instructed to attempt all questions within the time allotted.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    of 1

    Seat No.: _____ Enrolment No.

    ______

    GUJARAT TECHNOLOGICAL UNIVERSITY


    B.E. Sem-III Examination December 2009
    Subject code: 131901 Subject ame: Electrical Machines and Electronics
    Date: 17 / 12 / 2009 Time: 11.00 am – 1.30 pm
    Instructions: Total Marks: 70
    1. Attempt all questions.
    2. Make suitable assumptions wherever necessary.
    3. Figures to the right indicate full marks.

    Q.1 (a) Explain the working principle of DC generator. Also explain commutator 07
    action.
    (b) Explain parallel operation of alternators. 07

    Q.2 (a) Explain the different methods of speed control of DC shunt and series motor. 07
    (b) How the rotating magnetic field is produces in three phase induction motor, 07
    when three phase supply is fed to it? Explain with the help of phasor
    diagram.
    OR
    (b) Explain shaded pole induction motor in detail. 07

    Q.3 (a) State the types of instrument transformer and derive the EMF equation of 07
    single phase transformer.
    (b) A long shunt compound generator delivers a load current of 50 A at 500 V 07
    and has armature, series field and shunt field resistances of 0.05 ohm, 0.03
    ohm and 250 ohm respectively. Calculate the generated voltage and the
    armature current. Allow 2 V brush contact drop.
    OR
    Q.3 (a) What are the causes of low power factor? Explain various methods of power 07
    factor improvement.
    (b) A 500 V shunt motor runs at its normal speed of 250 r.p.m. when the 07
    armature current is 200 A. The resistance of armature is 0.12 ohm. Calculate
    the speed when a resistance is inserted in the field reducing the shunt field to
    80 % of normal value and the armature current is 100 A.

    Q.4 (a) List the different equipments used in transformer substation with their 07
    function.
    (b) A synchronous condenser absorbing 60 kW is connected in parallel with a 07
    factory load of 240 kW having a lagging power factor of 0.8. If the combined
    load has a power factor of 0.9 lagging, what is the value of the leading kVAR
    supplied by the motor and at what power factor is it working?
    OR
    Q.4 (a) Explain the full wave rectifier in detail with the help of circuit diagram and 07
    waveforms.
    (b) Compare AC and DC transmission. 07

    Q.5 (a) State and explain Boolean Laws. 07


    (b) Describe various types of tariffs. 07
    OR
    Q.5 (a) Draw block diagram of 8085 microprocessor. 07
    (b) Explain inverting and non-inverting comparator. 07
    ***********

    You might also like