News Releases 2017Meiden develops groundbreaking high-voltage switchgear
Meidensha Corporation (Meiden) has developed a new gas-insulated switchgear (GIS) equipped with a 204 kV vacuum circuit breaker (VCB) that capitalizes on Meiden’s expertise in vacuum technology. This is the first GIS in the world to have such a large voltage, and is expected to be used in extensions of Japan’s Shinkansen bullet train and when replacing industrial facilities.
204 kV Gas Insulated Switchgear
Much smaller GIS substation footprintThis GIS is an all-in-one product, which incorporates a circuit breaker (CB), disconnecting switches (DS), maintenance earthing switches (ES), buses, surge arresters (SAR), instrument transformers (VT, CT) and other equipment needed to receive electricity transmitted from the power grid. Existing substations that handle the same level of voltage have separate installations for each piece of equipment, meaning they take up a significant amount of space. Meiden’s latest GIS will enable substations to be built on considerably smaller parcels of land.
Utilizing Meidensha’s vacuum technologyA VCB serves as the GIS’s circuit breaker, which consists of a vacuum interrupter (in which a pair of electrodes open and close in a vacuum vessel), an insulator and an operating apparatus, all of which are installed in a container. Meidensha has been developing vacuum technology since the 1960s, and has sold products based on it to clients in Japan and abroad. In addition to VCB, gas circuit breakers (GCB) are often used for this purpose.
Main features of Meiden’s VCB-equipped GIS【Comparison with a facility composed of individual pieces of equipment】
1. Saving space
This product is an all-in-one unit. The space necessary for installation can be slashed by as much as 85 percent compared to what is required at a facility composed of individual pieces of equipment. It is suitable for small spaces such as in mountainous areas and basements.
【Comparison with GCB-equipped GIS】
A GCB uses sulfur hexafluoride (SF6) gas for circuit breaking, while a VCB is a switch that functions in vacuum. The latter uses SF6 gas only for the insulation. SF6 gas has a greenhouse effect 23,900 times that of carbon dioxide. The reduced use of SF6 gas with a VCB can help contribute to the prevention of global warming. In addition, SF6 decomposes into a harmful gas when the electrodes open and close in a GCB, and needs to be disposed of in accordance with the law. In a VCB, in contrast, SF6 does not turn into a harmful gas and is recycleable.
3. Reducing life-cycle costs
While a GIS installed with a GCB needs an overhaul inspection once every 2,000 cycles, a VCB-equipped product does not require an overhaul inspection until 10,000 cycles. This reduces maintenance and inspection costs, lowering the cost of the life cycle overall.
4. Improved reliability
・High circuit-breaking performance In a VCB, circuit breaking is done in vacuum, which creates superior insulation recovery between electrodes. This means a VCB can effectively interrupt large currents during short-circuits of an electric power grid, thus preventing accidents from spreading further.
・ Interruption performance when gas pressure is low A decrease in gas pressure will negatively affect a GCB, making circuit-breaking impossible. This is not an issue with a VCB because circuit breaking is performed in a vacuum, which enables it to interrupt load currents as normal, ensuring a safe and reliable supply of electricity.
Contact at Meiden on this press release:General Affairs & Public Relations Division