First, the isolation switch definition
The Disconnector is mainly used to reliably isolate the part of the high-voltage power distribution device that needs to be powered off from the live part to ensure the safety of the maintenance work. When the isolating switch is in the sub-position, there is an insulation distance and an obvious disconnection mark between the contacts in accordance with the specified requirements; in the combined position, it can carry the current under normal loop conditions and under abnormal conditions (such as short circuit) within a specified time. The current of the switching device.
Second, the working principle of the isolating switch
The contacts of the isolating switch are all exposed to the air and have obvious breaking points. The isolating switch has no arc extinguishing device and therefore cannot be used to cut off the load current or short circuit current. Otherwise, under the action of high voltage, the breaking point will generate a strong arc. It is difficult to extinguish itself, and may even cause arcing (relative to ground or phase-to-phase short circuit), burning equipment, endangering personal safety. This is a serious accident called "loading isolation switch".
The isolating switch can also be used to switch between certain circuits to change the way the system operates. For example, in a double bus circuit, an isolated switch can be used to switch a running circuit from one bus to another. At the same time, it can also be used to operate some small current circuits.
Third, the use of the sliding bearing of the rotating part of the isolating switch
The contact of the isolating switch, that is, the separating action of the isolating knife can be completed by manual and electric control, but in any case, it is required that the rotating parts can smoothly run under any circumstances, which requires the bearing of each rotating part to be longer. After the pause of time, it can still ensure normal operation; in order to ensure the normal operation of the isolating switch during the annual maintenance process, it is required that the sliding bearing of each rotating part can resist high and low temperature staggering all the year round and can still be used after the end face cover fails. Resist the erosion of various external factors, such as salt fog, acid rain, oxidative corrosion and other natural factors.
In the early days, the domestic and foreign isolating switch manufacturers were able to solve the various rotating parts of the isolating switch. After the long-term stop, the metal sliding bearings were used in all rotating parts, such as powder metallurgy bearings, copper alloy bearings and three-layer composite. Bearings; although these bearings have adopted the self-lubricating process, they can not change the disadvantages of metal bearings, such as the lubricant is easy to dry, the corrosion and rust after the cover fails, etc. The isolation switch can not ensure the normal operation after long-term stop. . At present, the domestic use of a certain proportion of the three-layer composite bearing, although the inner diameter of the working surface is sintered with a lubricating layer, but this layer of lubricating layer thickness is only 0.03mm, when the lubricating layer works off the surface of the rotating shaft and the underlying metal copper powder layer or low The direct contact of carbon steel may result in rust and adhesion of the shaft and the surface of the metal bearing after a long pause, and the isolating switch has a risk of failure. In order to completely solve these risks, European isolation switch manufacturers first began to try to use new plastic self-lubricating bearings and after years of use prove that engineering plastic self-lubricating bearings become the most effective means of isolating switches to solve the risk of rotational failure.
Fourth, the wear-resistant mechanism of self-lubricating plastic bearings
CSB-EPB series self-lubricating plastic bearings have excellent self-lubricating and wear resistance. CSB Company makes full use of self-lubricating material modification technology, and high-strength fiber is used in high-performance engineering plastics to improve the bearing capacity of materials. And the special grease reduces the friction coefficient of the material, thereby improving the comprehensive wear resistance of the material and prolonging the service life of the plastic bearing. (For details, please refer to China CSB Company "Engineering Plastics Self-lubricating Bearings" manual) High-performance engineering plastics as the base material mainly as wear-resistant carriers; reinforcing fibers improve bearing load-bearing and impact resistance; special greases reduce bearing friction The coefficient is self-lubricating.
