Abstract: A contact abnormality detection system for use in a gas-insulated switchgear or other power transmission or distribution apparatus. A gas-insulated switchgear includes a hermetic housing, an insulating gas sealed in the housing, and conductors in the housing having contacts for providing a path for a large current and being electrically insulated from the housing. An abnormality in the contacts causes the contacts to generate vibrations when a large current flows through them. A vibration detector detects vibrations generated by the switchgear including the vibrations generated by the contacts. The frequency spectrum of the vibrations detected by the vibration detector is analyzed to detect if the vibrations contain frequency components in the range of 200 to 500 Hz which meet predetermined criteria.

Abstract: A puffer type current interrupter employing a pair of symmetric electrodes with contact bosses provided on their confronting surfaces. An insulator nozzle is arranged such that the throat section for providing a jet of arc blasting gas is located in the periphery of the bosses. The electrode structure provides a uniform electric field between the electrodes, thereby gaining the breakdown voltage.