Buffering device for the operating mechanism of a switchgear, and method of lubrication thereof

摘要

A piston rod (15) and a first piston (13) are arranged in the interior of an external cylinder (11) and internal cylinder (12); a second piston for absorbing the change of volume of operating fluid (24) is also arranged therein. Also, a first return spring (18) for returning the piston rod (15) to the interruption position is provided and a second return spring (20) for returning the operating fluid 24 into the high-pressure chamber (25) by pressurizing the second piston (14) is provided. In addition, the air in the interior of the buffering device (10) is withdrawn by a vacuum pump (38), and operating fluid (24) is thus introduced in a degassed condition.

主权项

1. A method of lubrication of a buffering device of a movable electrical contact in an operating mechanism of a switchgear, the buffering device comprising an outer cylinder, and an internal cylinder provided in the outer cylinder and at least partially defining a pressure chamber for an operating fluid, the method comprising steps of:
arranging a lubricating plug at an end of an internal cylinder of said buffering device, a tip of said lubricating plug having a packing to seal the pressure chamber of the internal cylinder of said buffering device; providing a flow path in an interior of said lubricating plug, said lubricating plug being connected with a conduit that bifurcates into two branches; connecting one of said conduit branches with a vacuum pump; connecting another of said conduit branches with a container of the operating fluid; arranging a first valve on said one of said conduit branches; arranging a second valve on said another of said conduit branches; closing said second valve while opening said first valve and operating said vacuum pump, to put the pressure chamber into a vacuum condition; thereafter closing said first valve and opening said second valve, to introduce the operating fluid in said container into the pressure chamber and thereby lubricate the buffering device; and thereafter replacing said lubricating plug sealing the pressure chamber with another plug that seals the pressure chamber, wherein the another plug is coupled for movement with the movable contact.