1 Pulling and arcing method accelerates the separation of the contacts when the switch contacts are disconnected, and the arc is rapidly elongated, thereby reducing the electric field strength between the switch contacts, or the arc is insufficient to maintain the arc burning, and the arc is extinguished. .
a. Blowing out the arc with a gas. Use any airflow of a colder insulating medium to blow the arc (the direction of the airflow is parallel to the arc column) or cross the arc (the direction of the airflow is perpendicular to the arc column) to rapidly spread the arc and enhance the cooling. In order to achieve the purpose of arc extinguishing.
b. Multi-fracture arc extinguishing In high-voltage circuit breakers, there are often two or more series fractures per phase, which can divide the arc into multiple small arc segments. Its function is: under the equal contact stroke, the multi-fracture has a faster arc elongation than the single fracture, so the arc gap resistance increases rapidly, increasing the recovery rate of the medium strength; meanwhile, the voltage applied to each fracture is reduced. Small, the voltage recovery speed of the arc gap is reduced, and the arc extinguishing performance is good.
c. Using vacuum arc extinguishing vacuum has high insulation strength, the switch contacts are placed in a vacuum container, and the arc can be extinguished when the current crosses zero. To prevent overvoltages, the current should be abruptly zero when the contacts are not separated. A small amount of metal vapor should be generated between the contacts to form an arc channel. When the alternating current naturally drops past zero, these metal vapors quickly scatter in the vacuum to extinguish the arc.
d. The arc is divided into a plurality of short-arc AC arcs connected in series. At the moment of zero-crossing of the current, a dielectric strength of about 150-250 V occurs immediately in the vicinity of the new cathode in a period of 0.1 to 1 μ, which is called a new cathode effect. When the AC voltage applied to both ends of the contact is less than 150V, the arc will be extinguished. Cutting a long arc into several short arcs in series is to use a new cathode effect to extinguish the arc. Generally, an insulating plate is used to sandwich a plurality of metal grids to form an arc chute, covering the full stroke of the switch contacts. When the switch contacts are separated, the long arc is quickly moved into the arc chute under the action of electric power and magnetic field force, and the long arc is cut into a series of short arcs by the arc extinguishing piece. When the arc current crosses zero and the arc is extinguished, every two grids Immediately between the sheets, the dielectric strength of 150~250 volts is present, and n grids are provided. The total dielectric strength of the arc extinguishing grid is n (150~250)V. If the voltage between the contacts is less than the value. The arc cannot be maintained and the arc must be extinguished. That is to say, when the sum of the dielectric strengths of all the grids is greater than the voltage applied to the moving and static heads, the arc will not re-ignite.
e. Slot arc extinguishing slit arc extinguishing device using organic solid medium, arc extinguishing grid ceramic or organic solid material. When an arc is generated between the contacts, under the action of the magnetic field generated by the magnetic blowing coil, the electric power is generated by the arc, and the arc is elongated into the slit of the arc-extinguishing grid, and the arc is in close contact with the grid, cooling the arc, and strengthening free. At the same time, the organic solid medium decomposes under the action of high temperature to generate gas, the pressure is increased, the arc is cooled intensely, and finally extinguished. 2 The cooling and arc extinguishing method reduces the temperature of the arc and slows down the ion movement speed, so that the heat release effect is weakened, and at the same time The complex action of ions is also enhanced, which is conducive to the extinguishing of the arc. The lower the temperature, the stronger the composite action and the easier the arc is extinguished.
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