The potential of UHV converter transformer to ground is very high

so the test of longitudinal insulationunder impulse voltage is more stringent. In this paper

the equivalent longitudinal capacitance of interleave coil is de-rived which commonly used at the end of UHV transformer winding. The obtained equivalent circuit parameters areused to construct a multi-winding equivalent circuit model. The wave process of high voltage winding in UHV convert-er transformer under standard lightning full wave impulse is analyzed and calculated. The results show that the equiv-alent capacitance of interleave coil is much larger than that of ordinary coil

and the more number of parallel wires

the larger the equivalent capacitance. Therefore

interleave coil has more excellent anti-impulse performance.