Mercury arc valves for HVDC were, therefore, often constructed with four or six anode columns in parallel.
12.
From the 1920s on, research continued on applying thyratrons and grid-controlled mercury arc valves to power transmission.
13.
By the end of 2004 the last of the mercury arc valves in Pole 2 had been replaced by thyristor valves.
14.
The Inter Island link at the time was the last HVDC system in the world with mercury arc valve converters in operational service.
15.
The development of high power mercury arc valve converters in the 1950s led to the development of several HVDC transmission schemes in other countries.
16.
These valves, supplied by English Electric each had six anode columns in parallel and were the most powerful mercury arc valves ever built.
17.
In 1943 Lamm obtained his Ph . D . from the Royal Institute of Technology, studying part-time while developing the mercury arc valve.
18.
On 1 August 2012, Transpower decommissioned the remaining half of the Pole 1 mercury arc valve converter stations at Benmore and Haywards, after 47 years in service.
19.
Nevertheless the scheme provided valuable experience for designing the much larger ?00 kV Volgograd Donbass project which was completed in 1965 using mercury arc valves of entirely Soviet design.
20.
In 2004, the mercury arc valves groups were replaced with light-triggered thyristor groups to eliminate the environmental risks of maintenance costs of the obsolete mercury arc valves.
