mercury-arc valve

The first high power electronic devices were mercury-arc valves.

However realization was first possible in the 1920s, when mercury-arc valve rectifiers with control grids became available.

For many years this effect limited the practical operating voltage of mercury-arc valves to a few kilovolts.

The large switching devices for power transmission applications installed until 1970 predominantly used mercury-arc valves.

The first phase of the scheme, completed in May 1970, used only mercury-arc valves in the converters.

When it was built between March 1971 and October 1977, mercury-arc valves were used to rectify the alternating current.

Ignitrons are closely related to mercury-arc valves but differ in the way the arc is ignited.

Each 6-pulse converter bridges consists of 6 main Mercury-arc valves plus a 7th for high-speed bypass operations.

Originally mercury-arc valves were used as static inverter valves.

Early LCC systems used mercury-arc valves, which were rugged but required high maintenance.

Mercury vapors are used for applications with high current, e.g. lights, mercury-arc valves, ignitrons.

Mercury-arc valves had been the de facto standard for HVDC up to this time.

Converters using thyristors or mercury-arc valves are known as line commutated converters.

Mercury-arc valves were widely used until the 1960s for the conversion of alternating current into direct current for large industrial uses.

As a result, mercury-arc valves were much more rugged and long-lasting, and could carry much higher currents than most other types of gas discharge tube.

A mercury-arc valve rectifier station could convert AC to DC where networks were still used.

Rotary converters and later mercury-arc valves and other rectifier equipment allowed DC to be provided where needed.

The mercury-arc valve converter equipment was partially decommissioned in 2007, and fully decommissioned in August 2012.

In a mercury-arc valve, an arc forms between a refractory conductive anode and a pool of liquid mercury acting as cathode.

Early LCC systems used mercury-arc valves, with designs that had evolved from those used on high power industrial rectifiers.

Most applications of mercury-arc valves for rectifiers used full-wave rectification with separate pairs of anodes for each phase.

Early HVDC systems used mercury-arc valves, but since the mid-1970s, solid state devices such as thyristors are used.

Mercury-arc valves are prone to an effect called arc-back (or backfire), whereby the valve conducts in the reverse direction when the voltage across it is negative.

Its success has been such that a duplicate scheme has been built, although improved technology led to the mercury-arc valves being replaced by solid-state thyristor devices.

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.