Off-circuit tap-changer with shielding device

Abstract

A non-excited tap-changer with shielding device for a transformer includes an upper and a lower bearing (1,2). A rotating shaft (3) passes through the upper and the lower bearing (1,2) and is connected to an insulator (5). One end of the rotating shaft is connected to an operating mechanism (4). Moving contacts (7) are mounted on the rotating shaft and fixed contacts (6) are mounted correspondingly around the moving contacts. A cylindrical shielding housing (8) is covering the circumference of the fixed contacts. Also, an insulating drum is installed inside and / or outside of the shielding housing. A shielding coil is mounted on the one end or both ends of the cylindrical shielding housing. The non-excited tap-changer is compact and the reliability is enhanced.

Description

technical field [0001] The invention relates to an off-excitation tap changer with a shielding device used in a transformer, which is an improvement to the existing off-excitation tap changer. Background technique [0002] In Chinese patents CN2308152Y, CN2454878Y, and CN2249959Y, several off-excitation tap-changers and off-excitation drum tap-changers with different structures are proposed. These switches have compact structure and small volume, so they occupy a small space inside the transformer when used. , easy to operate, reliable and so on. However, with the increase of the rated voltage level of the switch and one of the main performance indicators of the transformer - the partial discharge limit requirement has been greatly increased, the partial discharge performance of the tap changer installed on the transformer with a higher voltage level often becomes the weak link of the transformer , because there are more exposed charged bodies on the tap changer, even if th...

AI Technical Summary

Problems solved by technology

Therefore, the external partial discharge of the switch is the key control link, and the partial discharge performance of the transformer is often unqualified due to high requirements on materials, structures and processes or failure to meet the requirements, or sufficient insulation distance must be left between the switch and the transformer box and coil To reduce the field strength, so that the volume of the transformer will be greatly increased, which will increase the switch manufacturing cost, the transformer use and manufacturing cost, and even the shipping cost, and the large partial discharge will also greatly reduce the reliability of the transformer operation.

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