Long-Lifetime Insulation Supporting Board in Tesla-Type Generators

An MV-class SF6-insulated supporting board for Tesla-type generators is proposed, which has the advantages of compact structure and lightweight, but its lifetime is short, only 30 000 pulses. Therefore, various techniques are employed to prolong the lifetime, which include grooving on the board surface, elimination of triple junction (TJ) regions, high-temperature drying, and control of water content in the surrounding SF6 environment. Each method is, respectively, researched. Small-scale experimental results demonstrate that grooving can increase the flashover voltage (
${U} _{f}$
) by 6.3%–13.8% and drying at 120 °C can increase
${U} _{f}$
by 4.3%. Simulation results reveal that eliminating the TJ regions of the assembled insulation supporting boards (ISBs) can reduce the maximum applied field (
${E} _{{\text {op}}}$
) in this region by 50%. Literature review suggests that controlling the water content in the neighboring SF6 gas under 500 part per million (ppm) can increase
${U} _{f}$
by 2.5%. All the four techniques are applied to a pair of ISBs in a Tesla-type generator, effectively extending the lifetime from
$30\circ 000$
to million class with an enhancement factor greater than 30.