Sulphur hexa:fluoride filled HV earthing switch - has expandable bellows which unlocks lever which actuates closure of earth switch

摘要

The sulphur hexafluoride filled earthing switch has a movable poker (26) which electrically connects to earth a fixed contact (28) of a bus-bar (12). In the envelope associated with the poker actuating mechanism (38) is an insulating gas pressure control detector. The pressure detector (24) has a deformable bellows (48) which presses against a lever (42) of the actuating mechanism (38). A channel (50) communicates between the envelope and the interior of the bellows. Sudden increase of pressure inside the envelope is translated by expansion of the bellows (48) followed by release or unlocking of the lever (42).