SU748551A1 - Method of cut-out arc extinguishing - Google Patents

Description

(54) METHOD FOR EXPOSING THE ELECTRIC ARC

I

The invention relates to electrical equipment and can be used for extinguishing an electric arc in high voltage switching devices.

As is known, the process of extinguishing an alternating current arc can be divided into two stages: the first stage covers the moment from the occurrence of an arc to the natural passage of current through zero; the second stage is after zero current until the voltage is fully restored at the open contacts. DC arc extinguishing is the first stage until the current zero-crossing, i.e. quenching, is reached, the second stage degenerates. The more arc energy is diverted from the arc column in the first stage, the more successful the process of the first step.

At the second stage, due to the collapse of the arc column: the need for a large energy output is eliminated, but it becomes necessary to ensure high dielectric strength of the gap.

. It is known that for extinguishing the arc in high-voltage apparatuses the following arc-suppressing mediums are most widely used: water, oil, air, SF6 {1. The use of each of these media is warranted as a DISABLE

Their following properties are necessary for the arc medium: high heat capacity, high thermal conductivity, high electrical strength. Electric water strength is extremely low and. This significantly limits its use as an arc-suppressing medium.

/ V Accurate electrical strength are oil and gas.

However, the oil switches explosions are fire hazards, and in the course of the operation of the appliance, the electrical strength deteriorates. SF6 has a very high electrical strength, but low heat capacity and thermal conductivity, and. therefore, not effective in the above first quench stage.

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Arc extinction in air has the disadvantage that air has a relatively low dielectric strength, which reduces the reliability of the switch and increases its size.

Thus, the analysis of thermophysical

20 and the electrophysical properties of arc-suppressing media used in engineering, shows that none of them is optimal, since they do not combine

at the same time high electrical strength and high thermophysical properties. This circumstance reduces the efficiency and reliability of arc suppression and switching capacity of switches. Nevertheless, in the breaker industry, the method of extinguishing was used, using one chemically homogeneous arc extinguishing medium in the arc chamber: oil — in oil switches, air — in air, and SF6 gas — in gas-insulated ones.

There is a known method of extinguishing an arc in switches using two different arc extinguishing media and, accordingly, two arc arresting chambers connected in series and operating simultaneously 2.

The disadvantage of this method is the complexity of its implementation, since it requires a combination of two arc-suppressing chambers in operation, which significantly increase the overall dimensions of the switch as a whole.

The purpose of the invention is to increase the efficiency and reliability of Dugogashein.

The goal has been achieved by extinguishing the arc, which is carried out in one arcing chamber of a switch in the following sequence in two stages. in the first stage, before the approach to zero, the arc in the chamber is extinguished in a high-temperature arc-suppressing medium, for example, oil; at the second stage, after a zero current, in a high-strength dielectric medium, for example, SF6 gas, helium, hydrogen. The change of the arc-suppressing medium in the chamber at the transition from the first stage to the second stage is carried out at the moment when the current passes through zero or with a slight lead over this moment, determined, for example, by a synchronization scheme. The magnitude of the advance depends on the volume of the chamber and the intensity of the evacuation from it of a high-heat arc-containing medium.

FIG. 1 and 2 are schematic diagrams of some of the possible designs that implement the proposed method of quenching.

FIG. 1, when contacts 1 and 2 are opened at the first stage of extinguishing, an extinguishing medium with high heat capacity, for example, liquid SF6 gas or oil from reservoir 3 is fed into the arc extinguishing chamber through valve 4.

In the second stage, the supply of this arc-suppressing medium is stopped and, through the same tpianaH, from the tank 5 is fed into the chamber

the second, high-strength dielectric arcing medium, naprnmer, gas, hydrogen.

In the design of FIG. 2 closed contacts I and 2 are located in chamber 3 filled with a high-temperature arc-suppressing medium, in which the first stage of arc quenching occurs when the contacts are opened. The moving contact 2 at some moment of its movement opens, acts as a valve, a window in the tank 5, filled with a high-strength dielectric medium, for example, SF6 or hydrogen, H thus accessing the latter into the chamber at the second and final stage of bleaching.

This method of extinguishing an electric arc shutdown provides, in comparison with known methods, the following advantages; the possibility of intensive arc cooling due to: the use of physical (heat-intensive) properties of the arc-suppressing medium; the possibility of creating the necessary electric strength in the arc-suppressing chamber after the passage of the current through zero; the possibility of creating on the basis of the proposed method of lightweight design of switches with increased switching capacity.

Claims (2)

1. Butkevich GV. Arc processes when switching electrical circuits. M., 1973, p. 66 2. USSR author's certificate number 526964, cl. H 01 H 33/60, 1976.