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    Expt 5 Open Saturation Curve of An Alternator

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    Ryan De Guzman

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    © All Rights Reserved
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    Expt 5 Open Saturation Curve of An Alternator

    Uploaded by

    Ryan De Guzman
    34 views5 pages

    Original Title

    Expt 5 Open Saturation Curve of an Alternator

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    © © All Rights Reserved

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    Copyright:

    © All Rights Reserved
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    Download as docx, pdf, or txt
    34 views5 pages

    Expt 5 Open Saturation Curve of An Alternator

    Uploaded by

    Ryan De Guzman

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 5

    Department of Electrical Engineering Laboratory Manual for DC/AC

    Machines

    Experiment No. 5
    OPEN SATURATION CURVE OF AN ALTERNATOR

    OBJECTIVE

    To obtain the necessary data for the open circuit saturation curve of an alternator

    EQUIPMENT INITIAL SETTINGS (double check)

    FH2 MkIV Test Bed Speed Range: 1800 rev/min


    Armature Rheostat: Set to infinity (∞)
    Field Rheostat: Set to zero
    DC Supply: Set to 110 V
    FH100 Slip Ring Machine
    FH50 DC Compound Machine
    FH3 MkIV Instrumentation Frame
    A2 DC Ammeter 500 mA Range
    V2 DC Voltmeter 150V Range
    V3 AC Voltmeter 250 V Range
    R1 Resistive Load 50 ohms Rheostat set to zero
    2,000 ohms Rheostat set to infinity

    PROCEDURES

    1. Position the FH100 Slip Ring Machine into the right-hand test position and the FH50 DC
    Compound Machine into the left-hand test position. Insert the 16-way plugs of each machine
    in their respective adjacent sockets on the Test Bed.

    2. Set up the equipment and connect as shown in the diagrams of Figure 5.1(a) and Figure
    5.1(b).

    3. Switch on the power to the FH2 MkIV Test Bed, first at the Mains Switch and then press the
    Green ON push button to activate the contactor.

    4. Start the FH50 drive motor (prime mover) by rotating the FH2 Armature Rheostat clockwise
    to zero, and then rotate the Armature Rheostat counterclockwise until the machine sped is
    1500 rev/min.

    5. Take readings of phase voltages for increasing values of field current from zero to values as
    indicated in the Results Table. Repeat for decreasing values of field current. The last trial for
    increasing values of field current is the first trial for the decreasing vales of field current.
    Maintain speed at 1500 rev/min for each trial to obtain good results. Record the results in
    Table 5.1.

    6. Plot graphs of average value of generated line to line voltage against field current for
    increasing and decreasing values of field current.
    Department of Electrical Engineering Laboratory Manual for DC/AC
    Machines

    SCHEMATIC DIAGRAM

    Fig. 5.1(a)

    WIRING DIAGRAM

    Fig. 5.1(b)
    Department of Electrical Engineering Laboratory Manual for DC/AC
    Machines

    QUESTIONS AND PROBLEMS

    1. Why is a three-phase AC generator also called a synchronous machine?

    2. Why is the rotor of an alternator constructed of thin lamination?

    3. Differentiate between salient pole rotor and non-salient pole rotor.

    4. Non-salient pole rotor are normally used for two and four pole rotor, while salient pole
    rotors are normally used for rotors with four or more poles Explain fully why these are
    so.

    5. The state-of-the-art in rotor field excitation for large three-phase alternators utilizes the so
    called brushless excitation. What is brushless excitation and give its advantages?

    6. Find the synchronous speed of an alternator with four pole rotor if the frequency of the
    supply voltage is 50 Hz.

    7. What are the advantages of a three-phase alternator over a single-phase alternator in a


    large-scale power system?
    Department of Electrical Engineering Laboratory Manual for DC/AC
    Machines

    PRELIMINARY DATA SHEET

    Experiment 5 - OPEN SATURATION CURVE OF AN ALTERNATOR

    NAME: ______________________________ DATE: ________________


    COURSE/SECTION: __________________ GROUP NO.: __________

    Table 5.1a Increasing Field Current


    Ef (V) If Eab Ebc Eca Eave
    0
    10
    20
    30
    40
    50
    60
    70
    80
    90
    100
    110
    120

    Table 5.1b Decreasing Field Current


    Ef (V) If Eab Ebc Eca Eave
    120
    110
    100
    90
    80
    70
    60
    50
    40
    30
    20
    10
    0
    Department of Electrical Engineering Laboratory Manual for DC/AC
    Machines

    _________________________
    Instructor’s Signature

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