FOR IMMEDIATE RELEASE No. 3238
TOKYO, January 17, 2019 - Mitsubishi Electric Corporation (TOKYO: 6503) announced today that it has developed two technologies for gas-insulated switchgears: an arc-cooling technology that achieves a 25 percent improvement in the interruption of electrical current in sulfur-fluoride (SF6) gas-insulated switchgears used in high-voltage power systems, and a high-density dielectric coating technology that improves insulation performance by 30 percent in high-voltage conductors. The two technologies will contribute to the further miniaturization of switchgears and help to reduce the use of SF6 gas, which has global-warming potential that is 22,800 times greater than that of CO2.
The interrupter has two pairs of electrodes that remain closed when electric power is supplied. When the electrodes are opened the current cannot be interrupted immediately due to the conductive arc. In conventional method, the arc is extinguished by flowing the arc with gas to lower its temperature. Mitsubishi Electric's new arc-cooling technology uses a unique coolant to generate a high-pressure gas jet to effectively cool and then extinguish the arc.
In the switchgear, compressed SF6 gas is injected between a metal high-voltage conductor and a grounded tank. If the conductor's metal surfaces are not coated, surface roughness of even just several μm can lead to electric discharges and thereby diminish the dielectric performance of the SF6 gas. Mitsubishi Electric's new dielectric coating technology inhibits such discharges for improved dielectric performance. In addition, densifying the dielectric coating layer suppresses discharges due to air in the dielectric coating layer.
A gas-insulated switchgear incorporates an SF6 gas tank, which also contains an interrupter and high-voltage conductor. Conventional designs required two interrupters to conform to Japan's JEC-2300 standard and the IEC 62271-100 international standard. However, Mitsubishi Electric's new gas-insulated switchgear requires only one interrupter thanks to the new arc-cooling technology for improved current-interruption performance. In addition, incorporation of a dense coating layer in the high-voltage conductor improves dielectric performance and thereby allows the distance between the conductor and the grounded enclosure to be shortened, which enables a smaller enclosure to be used. As a result, reducing the number of interrupters and tank size enables less SF6 gas to be used.
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