Operational and high voltage tests on thyristor valves for use in a standardized BB-system

A new valve design for HVDC BB-systems has been subjected to type tests based on the most stringent requirements from either one of the three documents presently available in the industry. All tests were passed successfully. There was no thyristor failure and the only capacitor failure was demonstrated to be caused by a manufacturing defect. Effects of the failure were limited to the particular thyristor level. Partial discharge measurements confirmed that due to the mechanical design, corona shielding of the thyristor modules is not required. An additional test with a simulated water leak proved that the test object withstood the test voltage well in excess of the time required for the leakage detection to operate