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Topic: POWER TRANSFORMER TEST

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Laksamana Muda
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POWER TRANSFORMER TEST
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POWER TRANSFORMER TEST

 

Types of testing for a power transformer are:

 

a.                 Insulation test

b.                 Continuity test

c.                  Ratio test

d.                 Pressure test

e.                  Oil breakdown voltage test

 

6.1 Insulation Test

 

a.     HV to E

 

R       -        E       =       Megaohm

Y       -        E       =       Megaohm

B       -        E       =       Megaohm

 

b.     LV to E

 

r        -        E       =       Megaohm

y        -        E       =       Megaohm

b        -        E       =       Megaohm

n        -        E       =       Megaohm

 

c.      Between HV / LV

 

R       -        r        =       Megaohm

Y       -        y        =       Megaohm

B       -        b        =       Megaohm

 

6.2 Continuity Test

 

a.     Between HV terminals

 

R       -        Y       =      

Y       -        B       =      

B       -        R       =      

 

b.     Between LV terminals

r        -        y        =       Megaohm

y        -        b        =       Megaohm

b        -        r        =       Megaohm

r        -        n        =       Megaohm

y        -        n        =       Megaohm

b        -        n        =       Megaohm

 

6.3      Ratio Test

 

This test is to make sure the transformer ratio, say 11,000/433V is true. Apply lower, safe and easy to calculate value of voltage, say 110V to the HV side of the transformer and measure voltage induced at the LV terminal. The voltage at the secondary LV side should be in the same ratio as the above ratio. It should be 4.33 volt between phases or 2.4 volt between phase and neutral.

 

6.4      Oil Breakdown Voltage Test

 

It has been explained in the previous topic.

 

6.5      Pressure Test

 

Apply 30 kV DC voltage between all the three phases on the HV side only and check the leakage current whether it is in the acceptable value.



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Staff Sarjan
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good..

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ZD
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Power transfomer test at Site..240MVA,90MVA,30MVA 275/132/33/11KV

1) insulation test

2) Polarization index test

3) Ratio test

4) Vector group check

5) Impedance Test

6) Zero Sequence Test

7) Winding resistance check

8) Calibration of indicating meter

9) Dielectric Test of Transfomer oil

10) Operating of tap changer control and cooler control

11) Transfomer Guard Test

12) AVR relay proctection 

13) Functional Test  RTCC panel..



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Staff Sarjan
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apakah maksud dy1 & dy11

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ZD
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dy1 n dy11..merujuk pada jenis sambungan transfomer HV DELTA(d)..LV STAR(y)..angka yg teakhir adalah nilai kedudukan winding menghadap HV dan LV..untuk menentukan dy1 atau dy11 dipanggil vector group TX..ujian vector group perlu dilakukan baru kt dapat mengetahui kedudukan winding HV dan LV..dengan melakAR betuk vector winding TX..

CARA PEGUJIAN..

shot winding Red phase HV dengan winding Red phase LV..apply voltage pada HV side 3 PHASE 415V dengan pada tap changer normal tap..kemudian measure setiap phase iaitu    AB  BC CA  AN  BN CN Aa Ab Ac Nc

                     Ba Bb Bc Nb Ca Cb Cc Nc Aa Ab'                                                                                                                                                                                                                              ab ac bc an bn cn Ac' Ba' Bb' Bc'    

                     Ca'Cb'Cc' Na' Nb' Nc' a'b'a'c' b'c'                            

 

HV SIDE= RYBN(A,B,C,N)

LV SIDE= rybn(a,b,c,n)                *jika TX winding sambungan delta neutarl bushing 

                                                      tiada jadi nilai n atau N abaikan..

 

kemudian lukis vector diagram dengan memasukan nilai voltage yg di measure tadi..menyikut scale yg dibuat contoh 30v=1cm..vector tersebut akan menenujukkan nilai dy1 atau dy11..

                                                                                  

 



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Staff Sarjan
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apa sebab diwujudkan dy1 n dy11? adakah ia mempengaruhi phase sequence & phase angle?? jika dalam protection kita tahu bahawa perbezaan antara negetive sequence (0) dan juga positive sequence (1)..adakah ia berkaitan??

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ZD
Laksamana Muda
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wah.. semakin menarik...

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Koperal
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tidak mempengaruhi phase angle..dy11 n dy1 dapt dilihat dengan melukis satu lakaran vector bagi menentukan kedudukan 1 atau 11 same seperti dalam name plate TX..



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Laksamana Muda
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ada tak sape2 boleh dapatkan lakaran vector tu?

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Henry Ford
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Staff Sarjan
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apa beza 1 dan 11 (nombor terakhir tu)

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ZD
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bro ezrier,

 

bley kongsi  method tuk Impedance Test?

 

smile



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impedance test..inject HV side(primary) 3phase..kemudian shot 3 phase LV side(secondry)..ambil reading volt dan amp..HV side sahaja..

Masukkan result test dalam fomula ini..

impedance %= Vm x Rated Current / Im x Rated Voltage x 100

lepas tu compare dgn tx name plate impedance..

lakukan utk 3 tap..hati2 sebelah LV amp tinggi lakukan dengan gunakan cable yg welding 300amp..atau test plug..

     



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Rekrut
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cik ezrie kje dgn cmpny mna??JBE?BQE?KT SYSTEM?TERACHI??


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Koperal
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JBE..bro keje mane tester jgk ke?



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aku dah thu sape gelaran ko..hahaha..pooooooooonnnnnn.huhu



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amy
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selalu nye test ape yg kite buat keatas OLTC?selain drpd function test la...ade pa pe test lg x?

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