The system was built using mercury-arc valves and other equipment removed from the Elbe Project in Berlin at the end of World War II.
[1] Although primarily experimental in nature, the system was the first true static, electronic, high-voltage DC scheme to enter service.
Initial operating experience was gained using three series-connected, single anode mercury arc valves in each converter arm, but by 1959 experience had been gained with operating with either one or two mercury arc valves in series per arm.
[3] The experience gained with multiple valves in series in each arm was not wholly successful and the little available literature suggests that the reliability of the scheme was poor.
This may have been because the valves, unlike those being developed in Sweden by Dr Uno Lamm, lacked the external anode voltage divider networks which were found necessary to obtain reliable operation at high voltage.