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Impedansi Trafo ( The impedance of a transformer)

13 Jun

Persentase Impedansi (Z%)

Sering kali kita temukan impedansi trafo pada setiap nameplate, tetapi apa sih sebenarnya yang dimaksud dengan Z% itu?

Persentase impedansi dari sebuah transformator ialah voltage drop pada keadaan full load yang disebabkan resistansi kumparan dan reaktansi bocor yang digambarkan sebagai persentase dari tegangan rating.

Selain itu juga menggambarkan persentase tegangan nominal terminal untuk melayani arus full load selama kondisi short circuit

Pengukuran Impedansi

Impedansi diukur dengan uji short circuit. Ketika salah satu kumparan dihubungsingkatkan tegangan pada kumparan yang satunya cukup untuk mensirkulasikan arus full load

Lihat gambar di bawah ini :

Persentase impedansi kemudian dapat dihitung sebagai berikut :

Z% = (impedance voltage/rated voltage) x 100

Percentage Impedance (Z%)

The impedance of a transformer is marked on most nameplates –  but what is it and what does the Z% figure mean?

Definition
The percentage impedance of a transformer is the volt drop on full load due to the winding resistance and leakage reactance expressed as a percentage of the rated voltage.

It is also the percentage of the normal terminal voltage required to circulate full-load current under short circuit conditions

Measuring Impedance
The impedance is measured by means of a short circuit test.  With one winding shorted, a voltage at the rated frequency is applied to the other winding sufficient to circulate full load current – see below:

The percentage impedance can then be calculated as follows:

Z% = (impedance voltage/rated voltage) x 100

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Posted by on 13 June 2011 in Istilah kelistrikan

 

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