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    Transformer Solved Problem

    Uploaded by

    Royce Palada
    This document provides test results and calculations for two distribution transformers. It asks the reader to: 1) Calculate equivalent circuit constants, efficiency, and voltage regulation for a 10-kVA transformer given open and short circuit test readings. 2) Determine core loss, equivalent resistances and reactances referred to the primary and secondary, voltage regulation, and efficiencies at full and half load for a 20-kVA transformer given its open and short circuit test results.

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    Transformer Solved Problem

    Uploaded by

    Royce Palada
    774 views4 pages
    This document provides test results and calculations for two distribution transformers. It asks the reader to: 1) Calculate equivalent circuit constants, efficiency, and voltage regulation for a 10-kVA transformer given open and short circuit test readings. 2) Determine core loss, equivalent resistances and reactances referred to the primary and secondary, voltage regulation, and efficiencies at full and half load for a 20-kVA transformer given its open and short circuit test results.

    Original Description:

    Regulation of a Transformer

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    This document provides test results and calculations for two distribution transformers. It asks the reader to: 1) Calculate equivalent circuit constants, efficiency, and voltage regulation for a 10-kVA transformer given open and short circuit test readings. 2) Determine core loss, equivalent resistances and reactances referred to the primary and secondary, voltage regulation, and efficiencies at full and half load for a 20-kVA transformer given its open and short circuit test results.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    774 views4 pages

    Transformer Solved Problem

    Uploaded by

    Royce Palada
    This document provides test results and calculations for two distribution transformers. It asks the reader to: 1) Calculate equivalent circuit constants, efficiency, and voltage regulation for a 10-kVA transformer given open and short circuit test readings. 2) Determine core loss, equivalent resistances and reactances referred to the primary and secondary, voltage regulation, and efficiencies at full and half load for a 20-kVA transformer given its open and short circuit test results.

    Copyright:

    © All Rights Reserved
    Download as DOCX, PDF, TXT or read online from Scribd
    Download as docx, pdf, or txt
    of 4

    ELECTRICAL APPARATUS AND DEVICES/ AC APPARATUS AND DEVICES

    EE 322/ EE 421
    SEMI FINAL-TERM EXAMINATION
    NAME: Palada, Royce M. COURSE & YR: BSEE - 3 ID.#: 18 - 41707

    1) The corrected instrument readings obtained from open and short-circuit tests
    on 10-kVA, 450/120-V, 50-Hz transformer are :

    O.C. test : V1 = 120 V; I1 = 4.2 A; W1 = 80 W; V1, W1 and I1 were read on the low-voltage side.
    S.C. test : V1 = 9.65 V; I1 = 22.2 A ; W1 = 120 W − with low-voltage winding short-circuited

    Compute :
    (i) the equivalent circuit (approximate) constants,
    (ii) efficiency and voltage regulation for an 80% lagging p.f. load,
    (iii) the efficiency at half full-load and 80% lagging p.f. load.
    Given:
    From O.C. test reading
    on the low-voltage side:
    From S.C. test reading with
    V1 = 120 V a low-voltage short circuited:
    I1 = 4.2 A V1 = 9.65 V
    W1o.c. = 80 W
    I1 = 22.2 A

    Required: W1s.c. = 120 W


    a. Ro and Do
    b. % regn and efficiency @ Full-load
    c. efficiency @ Half-load

    Solution:
    a. From O.C. Test

    Equivalent Circuits:
    From S.C. Test

    b. Total Transformation Drop as referred to primary

    For Full-load:

    c. For Half-load:
    2) A 20-kVA, 2200/220-V, 50-Hz distribution transformer is tested for efficiency and regulation as
    follows :

    O.C. test : 220 V 4.2 A, 148 W –l.v side

    S.C. test : 86 V 10.5 A, 360 W – l.v. side

    Determine:
    (i) core loss
    (ii) equivalent resistance referred to primary
    (iii) equivalent resistance referred to secondary
    (iv) equivalent reactance referred to primary
    (v) equivalent reactance referredto secondary
    (vi) regulation of transformer at 0.8 p.f. lagging current
    (vii) efficiency at full-load and half the full-load at 0.8 p.f. lagging current
    Given:
    From O.C. test reading From S.C. test reading with
    on the low-voltage side: a low-voltage short circuited:
    V1 = 9.65 V
    V1 = 220 V
    I1 = 4.2 A I1 = 22.2 A
    W1o.c. = 148 W W1s.c. = 120 W

    Required:
    a. Core loss
    b. R01
    c. R02
    d. X01
    e. X02
    f. V'1
    g. efficiency @ Full-load and efficiency @ Half-load
    Solution:

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