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 uses direct current (DC) for electric power transmission, in contrast with the more common alternating current (AC) transmission systems. Most HVDC links use voltages betwe ...

plant. The valves consist of

thyristor A thyristor (, from a combination of Greek language ''θύρα'', meaning "door" or "valve", and ''transistor'' ) is a solid-state semiconductor device which can be thought of as being a highly robust and switchable diode, allowing the passage ...

s, or at older plants,

mercury arc rectifier A mercury-arc valve or mercury-vapor rectifier or (UK) mercury-arc rectifier is a type of electrical rectifier used for converting high-voltage or high-Electric current, current alternating current (AC) into direct current (DC). It is a type of c ...

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 requires a stronger ceiling structure, however the hall and the static inverter can better survive

earthquake An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they ...

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

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 of high voltages, 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