SU635531A1 - Evacuated arc-extinguishing chamber contact system - Google Patents

Description

one

The invention relates to contact systems of vacuum arc extinguishing chambers containing contacting and arc extinguishing parts, in part, to the iodore of their material.

The known contact system 1, consisting of contacting and arc-extinguishing parts, in which the contact part is made of copper and silver-based alloys with bismuth or antimony, or a cermet composition with a refractory metal matrix, the pores of which are filled with the above-mentioned alloy, and the arc-extinguishing part - from copper.

The material of the arc-suppressing part of the contact system is selected so that it has a high breaking capacity and arc resistance. At the same time, the principle of selection of materials for the entire contact system as a whole, taking into account the correlation of their properties, is not proposed.

Typically, the design of the contact system sets a current path in which the arcing forces act on the arc to make it non-spinning from the contacting part of the system to arc extinguishing and then rotate before extinction. The speed of the arc and the conditions of this transition depend not only on the design of the contact system, but also on the properties

contact materials and the ratios of some of their characteristics, which are magnetic.

The purpose of the invention is to increase the breaking capacity and the life of the camera.

This is achieved by the fact that in the contact system of a vacuum arcing chamber containing contacting and arcing parts made of different materials, the arc extinguishing part is chosen at least in its peripheral region, and the ratio of the magnetic permeabilities of the arc extinguishing and contacting parts is

5000 1.4.

FIG. 1 shows the proposed contact system; in fig. 2 and 3 shows the distribution of the power lines of the contact system; in fig. 4 and 5 show embodiments of the contact system.

The contacting part consists of contacts 1 and 2, the arcing is made of electrodes 3 and 4. The contacts and electrodes are soldered to the inputs 5 and 6.

The current path in the contact system (iok

arc is in contact area)

can be represented by the curve LI, and after the arc non-spacing Ё is the area of the Arc AYY curve of the LZ.

Consider the distribution of magnetic induction lines at the surface of the electrodes, if any of the Materials of parts of the contact system is ferromagnetic.

It is known that at the boundary of two media with different magnetic permeability, the magnetic induction lines of force are refracted according to the law

tg4 J4

"2I-2

where ab 2 are the angles between the normal to the interface and the magnetic induction vectors in both media;

(d, 1 and 0.2 - magnetic permeability n -

Therefore, if the material of the contacts 1, 2 is ferromagnetic, and the arcing electrodes 3 and 4 are non-ferromagnetic, the distribution of the magnetic induction power lines in section xA-A (see Fig. 1) for the current path LI and BB for the path LZ has the form shown respectively in FIG. 2 and 3. (Fig. 2 and 3 denote D - arc, I - vacuum, II - ferromagnetic contact in sections A-A and B-B, respectively, B - magnetic induction lines).

With the passage of current along the path Li, the magnetic induction lines condense behind the arc front and thin out in front of the front. With the passage of current along the path LZ the opposite picture takes place. It is known that electrodynamic forces are directed from the area of condensation of magnetic induction lines to the area of rarefaction. Consequently, in this case, when the contacts 1, 2 are ferromagnetic, and the electrodes 3 and 4 are non-ferromagnetic, the high magnetic permeability of the material of the contacts accelerates the movement of the arc in the contact area and slows it down from moving to the arc-contact area. This effect was observed by experience.

In vacuum arc chambers, in which the contacting part is made of a cermet composition with an iron matrix, and the arc quenching is from copper, the arc either did not pass to the arc-suppressing electrodes, or was fixed at the boundary between the contacting and arc-quenching parts of the contact system. This led to a reduction in the breaking capacity of the system by half compared with the same system, made entirely of copper. The material of the iron-based contacting part has a number of advantages in comparison with the materials based on copper, and it has a lower cutting current and weldability, which is significantly less electrical outfit.

If the contacting and arc-extinguishing parts or only the arc-extinguishing part of the contact system are made of ferromagnetic metals, one should expect only a positive effect: acceleration of movement of the arc base at the surface of the electrodes and consequently reduction of wear and increase in breaking capacity.

In both cases, the following condition must be met: the magnetic permeability of the material of the arcing part must be at least 1.4 times greater than that of the material of the contacting part of the system. In the manufacture of the contacting part from the composition of 70% iron, 4% antimony, and the rest from copper or oxygen-free copper, and arcing from iron, an increase in twofold capacity was observed in comparison with the previously tested system.

Similar results took place in the manufacture of the contacting part from copper, and the arc suppressant from the composition of 70% iron and the rest - copper. In the first case

the ratio was 1.4, and in the second, jj

,four.

In the case of the manufacture of the arc-suppressing part of the system from a ferromagnetic metal, one should expect another positive

effect. The arc-suppressed part of contact systems, as a rule, has a design based on the principle of a rail plasma accelerator. With the end of the rail, there is a release of plasma clots that fall on the surface surrounding the contact system. This surface always contains chemisorbed gases that are released when interacting with the plasma. As a result, the pressure in the vacuum interrupter chamber may rise to an unacceptable level, and the chamber will fail. Forces pressing an arc to a ferromagnetic metal, arising at the periphery of the arcing part of the system, if

ferromagnetic, in the same way as in the case of the passage of current along the path LZ (Fig. 1), prevents the ejection of plasma bunches on the surface surrounding the contact system, as a result of which the amount of desorbed gases decreases. To obtain this effect, not all is enough, but only the peripheral part of the contact system, is made of a ferromagnetic metal (Fig. 4, 5).

FIG. 4 and 5, one pole of the contact system is shown, where 7 is a contact, 8 is an arc-suppressing electrode, 9 are slots in an arc-suppressing electrode, or similar to that shown in FIG. 4 and 5, io with slots having the opposite direction, i.e. the second pole may be a mirror image of the first. The opposite parts of the arcing electrodes located between the corresponding slots form rail accelerators. Parts 7, 8 are made of non-ferromagnetic metals, on the periphery of the contact system there are ferromagnetic linings 10 (fig. 4) or ring 11 (fig. 5).

In the Dyayy contact system The following combinations of contact materials can be used, weight. %:

I.Contacting part

Iron70 Iron70

Antimony4 or Bismuth 1-3

Copper Rest Copper Rest The arc part consists of iron and nickel. The ratio is 1.4.

FK

II.Contacting part

Bismuth alloy 0.5-1

Bor0,009-1

CopperE rest

The arc section consists of an iron composition of 70 wt. % and copper - the rest; iron, nickel.

Attitudes, 4.

to

In each variant, any combination of the indicated materials is admissible subject to a ratio of 1.4. Can prn-to

other materials not listed above may also be changed, the combination of which corresponds to the invention.

The ratios of the magnetic permeabilities of the materials of the arc-suppressing and contacting parts are obtained by substituting the values of magnetic permeabilities and the content of the ferromagnetic material in the arc-suppressing and contacting parts into the following formula:

J - d

Ij-k (f-ck) -rm

where Xd is the magnetic permeability of the arc-suppressed part;

IR - magnetic permeability of the contacting part;

Цф - magnetic permeability of ferromagnetic material;

m-magnetism mestDY; . Sk is the content of ferromagnetic material in the arc extinguishing and contacting parts.

For the first example, substituting numerical values in the formula, we get

Nd Yf F Sc, Cd to (, Ck) + {1. „Ck

1.0 weight.h.

100

or 70%

0.7 weight.h.

For the second example

5000-1

 5000

% OU in connection with the foregoing

l

5000:

1.4.

(Av

Claims (2)

1. US patent number 2975255, class. 200-144, 1961. 2. The patent of England No. 1194674, cl. H IN, 1970.