Abstract:
This invention relates to compressed-gas-insulated systems. An adherent or sticky coating is provided on selected surface areas inside compressed-gas-insulated systems to trap, or to captivate conducting and non-conducting particles, which if allowed to remain free can promote breakdown metallic parts or electrodes maintained at different potentials, or tracking and flashover along insulating surfaces. Preferably, a coating is provided which is initially hard or solid with adequate mechanical strength so that the system components can be easily handled by workmen during manufacturing and assembly without difficulty, and not at this stage capture unwanted particles. At a later time, following assembly operations, the surface layer of said coating is rendered adherent, or tacky to trap or to captivate conducting and non-conducting particles. During this stage mechanical means such as vibrations and/or gas flow and/or electric fields may be used to transport unwanted particles to the tacky or captivating areas. Following such captivation, the adherent, or sticky coating may be rendered hard again to trap the unwanted particles permanently. Alternatively, if desired, the coating may be rendered tacky, or captivating again during the life of the equipment to trap unwanted particles generated within or introduced into the system, thus performing a repair or reconditioning of the system. Another alternative is to maintain the coating sticky or tacky during the operating life of the electrical equipment and rendering the surface hard only during repair or maintenance operations when the system is opened and thus subject to handling and thereby large amounts of unwanted particles.
Abstract:
A gallium cathode high voltage ignitron for synchronous closing of EHV circuit breakers, is provided, to control switching surge overvoltages. Due to the fast triggering time of the gallium cathode ignitron the circuit can be closed synchronously without pre-insertion resistance to obtain a switching surge level of 1.5 per unit or less.