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    Transformer2 1250 Kva

    Uploaded by

    Vishal Kumar Singh
    The document details test results for a 1250 KVA power transformer. It includes equipment details, testing equipment details, insulation resistance tests, PI tests, voltage ratio tests, no load loss tests, magnetic balance tests, winding resistance tests, vector group tests, percentage impedance tests, and functional checks. The tests show most results are satisfactory except the PI value for LV to earth is low.

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    © All Rights Reserved
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    Transformer2 1250 Kva

    Uploaded by

    Vishal Kumar Singh
    82 views4 pages
    The document details test results for a 1250 KVA power transformer. It includes equipment details, testing equipment details, insulation resistance tests, PI tests, voltage ratio tests, no load loss tests, magnetic balance tests, winding resistance tests, vector group tests, percentage impedance tests, and functional checks. The tests show most results are satisfactory except the PI value for LV to earth is low.

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    TRANSFORMER2 1250 KVA

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    The document details test results for a 1250 KVA power transformer. It includes equipment details, testing equipment details, insulation resistance tests, PI tests, voltage ratio tests, no load loss tests, magnetic balance tests, winding resistance tests, vector group tests, percentage impedance tests, and functional checks. The tests show most results are satisfactory except the PI value for LV to earth is low.

    Copyright:

    © All Rights Reserved
    Download as DOC, PDF, TXT or read online from Scribd
    Download as doc, pdf, or txt
    82 views4 pages

    Transformer2 1250 Kva

    Uploaded by

    Vishal Kumar Singh
    The document details test results for a 1250 KVA power transformer. It includes equipment details, testing equipment details, insulation resistance tests, PI tests, voltage ratio tests, no load loss tests, magnetic balance tests, winding resistance tests, vector group tests, percentage impedance tests, and functional checks. The tests show most results are satisfactory except the PI value for LV to earth is low.

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    © All Rights Reserved
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    1.

    EQUIPMENT DETAILS:
    Make POWER STAR Rating 1250 KVA
    Sl. No. PS/1250-1274 Cooling ONAN
    HV (Volt) 11000V Gross Weight 4910
    LV (Volt) 433V HV (Amps) 65.61 Amp
    % Z Impedance 5% LV (Amps) 1666.72 Amp
    Qty of Oil 1601 LTR Vector Group Dyn11
    Mfg. Year 2010 Connection (HV) Delta
    No of Taps 1-5 Connection (LV) Star
    Normal Tap 3

    2.TESTING EQUIPMENT DETAILS:

    CALIBRATION
    INSTRUMENT MAKE SL. NO. RANGE
    DUE DATE
    Digital Insulation
    Motwane A02747121 0 – 5 KV 12-01-2023
    tester
    Transformer Winding
    Scope 2304.08AI1035 0-10 A/0-2000 Ω 12-01-2023
    resistance
    Digital Multimeter Fluke 55030407 0-1000 V 12-01-2023
    Milli Clamp Meter Multi B02850 30 mA – 300 Amp 12-01-2023

     Test Condition : Both Side Cable Disconnected . Temp:- 22ºC

    3. INSULATION RESISTANCE TEST :

    Description Voltage(KV) 1 Min 10 Min PI value Remarks

    HV to LV 5.0 KV 4.18 GΩ 5.89 GΩ 1.40 P.I Value is OK

    HV to EARTH 5.0 KV 4.04 GΩ 5.47 GΩ 1.55 P.I Value is OK

    LV to EARTH 0.5 KV 96.4 MΩ 115 MΩ 1.19 P.I Value is Low

    *While taking IR for winding, other winding to be shorted & grounded except while taking IR value
    HV/LV. Wdg to be guarded in case of three phase Wdg Trf .

    4. PI TEST :
    Time HV to LV HV to EARTH LV to EARTH Remarks
    15 Sec 1.82 GΩ 2.78 GΩ 89.6 MΩ OK
    1 Min 4.18 GΩ 4.04 GΩ 96.4 MΩ
    2 Min 4.97 GΩ 4.59 GΩ 97.5 MΩ
    3 Min 5.36 GΩ 4.87 GΩ 87.9 MΩ
    4 Min 5.35 GΩ 5.03 GΩ 86.0 MΩ
    5 Min 5.63 GΩ 5.13 GΩ 88.9 MΩ
    6 Min 5.69 GΩ 5.23 GΩ 89.8 MΩ
    7 Min 5.75 GΩ 5.32 GΩ 95.1 MΩ
    8 Min 5.79 GΩ 5.38 GΩ 104 MΩ
    9 Min 5.82 GΩ 5.42 GΩ 110 MΩ
    10 Min 5.89 GΩ 5.47 GΩ 115 MΩ

    5. VOLTAGE RATIO TEST WITH MAGNETIZING CURRENT

    HIGH VOLTAGE SIDE


    Tap Applied Voltage (In Volts) Measured Magnetizing. Current in (mA)
    Position R-Y Y-B B-R R Y B
    1 400.8 401.3 399.1 14.32 16.68 6.75
    3 400.3 403.2 399.2 14.39 16.79 7.37
    5 400.7 404.3 399.9 14.69 17.26 8.10

    LOW VOLTAGE SIDE


    Tap Measured Voltage (Volt) Measured Voltage (Volt)
    Position r-y y-b b-r r-n y-n b-n
    1 15.14 15.10 14.33 8.66 8.78 8.67
    3 15.90 15.87 15.62 9.10 9.24 9.10
    5 16.77 16.75 16.58 9.64 9.73 9.62

    6. NO LOAD LOSS : (Preferably From HV Side) ( In Normal Tap ) :


    Applied Voltage (In Volts) Measured Current (A/mA) Total Loss Remarks
    V RY V YB V BR IR IY IB (Watts) Loss Calculated at
    400.3 403.2 399.2 14.39 16.79 7.37 3080 rated voltage

    7. MAGNETIC BALANCE TEST : HV / LV Side :( STAR WINDING )

    Applied Voltage (In Volts) Measured Voltage (In Volts) Measured


    current Remarks
    r-n y-n b-n r-n y-n b-n
    (Amp)
    100.1 ---- ---- ---- 78.18 21.89 1.90
    ---- 100.7 ---- 50.88 ---- 49.92 1.36 OK
    ---- ---- 100.8 20.46 79.80 ---- 2.01
    8. WINDING RESISTANCE TEST : (In normal tap)

    HIGH VOLTAGE SIDE


    HV Between R-Y Between Y-B Between B-R Remarks
    Winding
    Tap. No. Asc Asc Asc
    OK
    3 1704.0 mΩ 1693.1 mΩ 1692.8 mΩ

    LOW VOLTAGE SIDE


    Lv r-y y-b b-r r-n y-n b-n
    Winding 2.287 µΩ 2.294 µΩ 2.298 µΩ 1.255 µΩ 1.246 µΩ 1.248 µΩ

    9. VECTOR GROUP TEST (HV-LV) : (At normal Tap for DYn11)


    Applied Voltage (Volt) Measured Voltage (Volt)
    R-Y 400 B-b 386.7 Y-b 387.4
    Y-B 405.5 B-y 401.89 Y-y 386.4
    B-R 399.5 R-n 9.15
    Y-n 391.8

    Inference :

    VBb < VBy


    VYy = VYb Hence It is DYn11.
    Rn+ Yn = RY
    10. PERCENTAGE IMPEDANCE TEST : ( At Normal Tap )
    Winding Shorted at L.V Side :- r, y, b shorted.
    PHASE Current (A) Current (A) Average
    Voltage (Volt) Remarks
    REFERENCE HV Side LV Side %Z
    R-Y 70.2 4.87 126.7
    Y-B 71.3 5.16 133.2 5.004 OK
    B-R 69.2 5.02 122.5

    11. FUNCTIONAL CHECKS :


    Alarms on
    Devices Set Value Simulation Aux Relay Lock out Remarks
    SER
    Buchholz Trip NA By shorting NA NA OK OK
    By moving
    PRD Trip NA NA NA OK OK
    PRD flag
    By moving Circuit checked
    OTI Alarm 85ºC NA NA NA
    dial till panel
    By moving
    OTI Trip 90ºC NA NA OK OK
    dial
    By moving Circuit checked
    WTI Alarm 85ºC NA NA NA
    dial till panel
    By moving
    WTI Trip 90ºC NA NA OK OK
    dial
    Remarks :-i) PI Value of LV to EARTH Is Low But IR Value Is Ok.
    ii) Rest Test result found satisfactory.

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