voltage transformer errors

[padraic]

Can anyone describe the effect of frequency on the ratio and phase angle errors of a vt?<br>
Specifically is it possible to test at 50hz and infer by calculation or M&G diagram the errors at other frequencies.<br>
Regards.

 

[merbas]

As far as I remember, in the AC line frequancy is very determined parameter for distribution lines. because all power facteurs and transfers depend on it.<br>
<br>
Voltage transformators ie measurement one, only degrade the line voltage into measurment divice range, and effect from line frequancy.<br>
<br>
because when F is decrease, main power vektor turn low speed and decrease the GAUSS LOSTS in the metal magnet also.<br>
<br>
remember when the frequancy high all tranformator event measurement ones start to gýve voýce like "ýnnnnnn" why ?<br>
<br>
because increase eddy currents and Gauss losts.<br>
<br>
invert of this, decrease the frequency, decrease the lost.<br>
<br>
therefore voltage tranformators effected by change of frequency. But DONT forget:<br>
class of transformator (such as Class 1 or 2) <br>
Measurement Divice sensitivity<br>
Measurement Faults delta F = step range / total range<br>
relative Faults<br>
<br>
generally greatter than , frequancy effect. Therefore You CAN ignore this FAULT , beside of MEASUREMENT FAULTS.<br>
<br>

 

[jbartos]

1/29/00<br>
One of the way to answer your question is over an electrical equivalent circuit of the transformer. It has passive elements such as inductances (and at high frequencies capacitances). This means that the inductive reactances (capacitive reactances at high frequencies) will appear. Since these reactances are dependent on the angular frequency which is equal 2 x PI x frequency (60Hz in America, some parts of Japan, some ships, etc., and 50Hz in Europe, some parts of Japan, and many other parts of the world), necessary adjustments or substitutions in equations for the proper transformer characterization must be made to stay on the accurate side. The more detail analysis would also include frequency influence due to so-called Foucault or Eddy Currents and the Steinmetz's Law (or Formula). But these would be linked more to the transformer losses and the transformer efficiency.