Analysis of the test line impedance and strength for short time and peak withstand test of KERI's new high power laboratory

Abstract

KERI have been expanding their high power laboratory from 2011 to 2015. Expansion test category includes short time and peak withstand test as well as short-circuit test. In case of short time and peak current with stand test, test current is mainly dependent on the line impedance of secondary part of short time withstand transformer since the secondary side voltage is 1000V or 500V. Because one of objective of this test is ACB with test voltage and current 635V and 85kA, the line impedance should be very low. In this paper, line impedance and strength between the test lines was analyzed according to the distance and arrangement by using finite element method. First, the flux line was calculated from the test line and those inductances are induced from energy stored of magnetic fields. The calculated results were compared in accordance with the position to reduce line impedance and find out the best arrangement way. Second, electromagnetic force between lines are also analyzed since short time and peak current withstand test usually needs very high current. Before selecting and spacing a support insulator, the engineers should check that insulator can endure electromagnetic force. In order to calculate electromagnetic force of the test line, we calculated magnetic flux density on the busbars designed to be installed in the test room. And those results was also compared with the tensile and compression strength of the designed supports. As a results, parallel line of same phase should be installed in a long distance and the short distance between other phases can decrease the line impedance. Because very short distance between other phase induces strong force, the engineer should consider the forces and cantilever strength of supports.