A valve hall is a building which contains the valves of the static inverters of a

high-voltage direct current A high-voltage direct current (HVDC) electric power transmission system (also called a power superhighway or an electrical superhighway) uses direct current (DC) for electric power transmission, in contrast with the more common alternating curre ...

plant. The valves consist of

thyristor A thyristor () is a solid-state semiconductor device with four layers of alternating P- and N-type materials used for high-power applications. It acts exclusively as a bistable switch (or a latch), conducting when the gate receives a current ...

s, or at older plants,

mercury arc rectifier Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Mercury ...

s. Mercury arc rectifiers are usually supported by insulators mounted on the floor, while thyristor valves may be either supported by

insulators Insulator may refer to: * Insulator (electricity), a substance that resists electricity ** Pin insulator, a device that isolates a wire from a physical support such as a pin on a utility pole ** Strain insulator, a device that is designed to work ...

or hung from the roof of the valve hall. The latter required a stronger ceiling structure, however the hall and the static inverter can better survive

earthquake An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fr ...

s compared to valve structures standing on the floor. A valve hall is equipped with heating and cooling equipment to control the temperature of the mercury arc rectifiers (which operate best over a narrow temperature range) or thyristors. The valve hall also protects the valves from weather and dust. Several valve assemblies, connected in series for the required terminal voltage, may be installed in the valve hall building. High voltage bushings are supported through the walls of the valve hall, to allow connections between the converter

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

s on the one side and the DC switchyard on the other. Beside the valve hall there is often an additional building, in which are control electronics, equipment for valve cooling and valve monitoring, station service power distribution, and amenities for the plant workers. Because very high voltages are present while the inverters are in operation, access to the valve halls is limited while the static inverter is running. The auxiliary control building may have windows to observe the valve hall, but usually the converter is remotely controlled. To protect communication systems from electromagnetic interference, valve hall buildings must have shielding installed to control emission of radio-frequency energy. At some HVDC converters such as at Cabora-Bassa, outdoor valves are installed in oil-immersed containers. At such plants no valve halls or wall bushings are required.

References

{{Reflist High-voltage direct current de:Stromrichterhalle

See also

References