Introduction to high voltage isolating switch
High-voltage isolating switch is an important switch device in the electrical system of power plants and substations, and needs to be used in conjunction with high-voltage circuit breakers. The isolation switch is suitable for indoor devices with three-phase AC 50Hz and rated voltage 12KV. It is used to connect, cut off or switch the line of high-voltage equipment under voltage and load. Its main function is: to ensure the safety of high-voltage electrical appliances and devices during maintenance work, and to isolate the voltage. It cannot be used and cut off, input load current and break short-circuit current. It can only be used for certain switching operations that do not generate strong arcs. That is to say, it does not have the arc extinguishing function; according to the different installation locations, it is divided into indoor and outdoor types. According to the number of insulating pillars, it is divided into single-pillar, double-pillar and three-pillar. There are optional equipment for each voltage level. .
Commonly used high-voltage isolation switches are GN19-10, GN19-10C, and similar old products are GN6-10, GN8-10. Take GN19-10 as an example,
It mainly includes the following parts:
Conductive part
The static contact is formed by a copper plate bent at a right angle, one end of which has a hole can be connected to the bus bar by a screw; the other end is shorter, and it contacts the moving blade (moving contact) when closing.
Two copper plates form a contact strip, which is also called a movable contact, which can rotate around a certain angle on the axis, and it clamps the static contact when closing. There is a clamping spring between the two copper plates to adjust the contact pressure between the moving and static contacts. At the same time, when the two copper plates flow in the same direction, they will generate an electromotive force attracting each other, which increases the contact pressure. Improved operational reliability. A galvanized steel sheet called a magnetic lock is installed at both ends of the contact strip, which ensures the mutual attraction force generated after the magnetic lock is magnetized when the short-circuit fault current flows, and strengthens the contact pressure of the contacts, thereby improving the movement of the isolation switch. , Thermal stability.
Insulating part
The moving and static contacts are respectively fixed on two sets of supporting porcelain bottles. For the model with C, the movable contact is fixed on the sleeve porcelain bottle. In order to insulate the moving contact from the metal and grounded transmission part, a porcelain-insulated tie rod insulator is used.
Transmission part
There are spindles, arms, tie rod insulators, etc.
Composed of steel frame. The supporting porcelain bottle or casing porcelain bottle and the transmission spindle are fixed on the base. The base should be grounded. In short, the isolating switch has a simple structure, no arc extinguishing device, an obvious disconnection point when in the disconnected position, and its opening and closing state is very intuitive.
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