Study of the behavior of transformer insulation under non standard impulse voltages

Abstract

The efficacy of a power system depends mainly on the reliability of newlinethe power equipment connected to the system The power transformer is the newlinemost significant component in a power system whose reliability mainly newlinedepends on its insulation Sets of routine and type tests are done to assess the newlinedielectric integrity of the completed transformer The test voltages are of newlinedifferent types viz power frequency lightning impulse and switching newlineimpulse In case of tests with lightning impulse voltage standard wave shape newlinetransformers it is very difficult to generate impulse voltages with standard newline1250 s waveshape Even if it is tested with standard waveshape parts of the newlinewindings undergo stress with nonstandard impulse voltages of both newlineunidirectional and bidirectional oscillatory waveshapes Moreover during newlineoperating conditions most of the power apparatus in the power system are newlineexposed to impulse voltages of nonstandard waveshapes which are not newlineaccording to the shape defined in standard IEC 60060 newline newline