ELECTRO STATIC AND ELECTRO MAGNITIC INDUCED CURRENT SWICHING OF EARTH SWITCHES

J.Santhosh & K.N.Srinivasan

The transmission lines and sub-stations for EHV and UHV electrical system are multiconfigured and complex.  It has been observed that there has been significant value of currents and voltage induced in the non-energized  and earthed portion of the transmission lines  due to the influence of adjacent energised lines .This phenomenon happens due to electro static and electro magnetic coupling between the  lines.  Hence the high voltage earthing switches have to be carefully designed to successfully interrupt the induced currents, which involves long arcs and significant current and voltage magnitudes. There has been a new IEC standard, which gives the induced current test requirements for high voltage earthing switches. In our laboratory, the relevant test circuits are simulated for conducting electro static and electro magnetic tests on HV earthing switches.The  test  simulation  and test results   for 245 kV and 420 kV earthing switches will be discussed in the paper.

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