Current limiter

FIELD: electrical engineering; short-circuit protective gear.

SUBSTANCE: proposed liquid-metal current limiter designed for use in up to 0.4 kV power networks to protect power loads against short-circuit currents has insulating bushing with axial bore receiving internal loosely mounted ball-shaped ceramic part of strict geometrical dimensions, and easy-to-manufacture narrow neck disposed at cross-sectional area of internal ceramic part, along its diameter and diameter of insulating bushing. Either side of bushing mounts contact leads, bellows being attached to one of them. Inner cavity of bellows and that of insulating bushing, as well as neck are filled with liquid metal.

EFFECT: reduced risk of damage to bushing and ceramic part; enlarged functional capabilities due to ability of in-service variation of narrow neck section.

1 cl, 4 dwg

 

The invention relates to the field of electrical engineering, namely the liquid metal current limiters.

The current limiters are used in electrical networks with voltage up to 0.4 kV to protect electricity consumers from short circuit currents. The main part of the current limiter is a ceramic sleeve. The ceramic sleeve is produced by molding the hot slurry in molds under pressure. For registration narrow isthmus (channel) in the form should be placed pin (badge), the shape of the isthmus. Stud (s), with a diameter of less than 0.5 mm under the action of the flow of mass in the form, as a rule, bend, break or deviate from the axis, making it impossible to release the details of the forms is the lack of available current limiters, as the conditions under which these devices are often the problem arises in the use of limiters with a cross section of the isthmus is less than 0.5 mm Narrow isthmus dielectric sleeve it is also impossible to machining to ensure a well-defined size. The size of the isthmus may vary, as the final size depends on the mode of annealing and the degree of shrinkage of the ceramic. The size deviation contributes to the wear marks form when the release of details from the form. However, changes in the size of the narrow isthmus (to the Nala) cause changes in currents and time delay of the current limiter, what is the main disadvantage.

Known current limiter made at least one narrow isthmus (channel)containing dielectric sleeve with an axial bore in which is placed the inner ceramic part in the form of a cylinder with longitudinal grooves on the lateral surface so that the longitudinal grooves, together with the inner surface of the dielectric sleeve, form narrow passages (channels), damping site, filled with molten metal, and the contact pin, which is the closest device to the same destination to the claimed invention by a combination of traits and adopted for the prototype (See. A.S. 1104600 the USSR, MKI3H 01 H 87/00).

For reasons that impede the achievement of specified following technical result in the manufacture and use of the prototype include the following: the need to use precise production equipment for receiving at least one narrow isthmus. Primarily this relates to the question of making slots strict geometrical dimensions on the surface of the inner ceramic part. There is also a risk of mechanical damage such as scratches and chips when fitting the inner surface of the dielectric sleeve and the outer surface of the ceramic parts, the density of connections which is y the em device. The inability to change the cross section of the narrow isthmus for the performance of repair works

The drawing of the prototype (figure 1) includes a dielectric sleeve 1 within which is located the inner ceramic part 2 in the form of a cylinder with longitudinal grooves 3. The sleeve on both sides are the contact pins 4 and 5, one of which is attached to the bellows 6. Narrow passages of the dielectric sleeve and the internal cavity of the bellows 6 is filled with liquid metal 7. Figure 2 shows a section a-a figure 1.

The dignity of the prototype in comparison with analogues performing a narrow isthmus in the dielectric sleeve similar shape, which is not possible when using the hot injection molding.

The technical result - the simplification of the manufacture of narrow isthmus, multiple decrease the risk of mechanical damage of the dielectric sleeve and the inner ceramic part, the enhanced operational capabilities - the ability to change the cross section of the narrow isthmus for the performance of repair work.

This technical result in the implementation of the invention is achieved in that in the known device the current limiter instead of the internal ceramic parts in the form of a cylinder with grooves inside the dielectric sleeve with an axial hole is placed internal Kera is practical detail in the form of a sphere strict geometric sizes in diameter, the smaller diameter of the dielectric sleeve. Role conductive narrow isthmus in this design fulfills the gap between the inner surface of the hollow cylinder and the surface of the dielectric tube in the shape of a ball. The narrow isthmus is in the place of the cross-section of the inner ceramic part according to its diameter and the diameter of the dielectric sleeve. For the performance of repair work the current limiter section of the narrow isthmus can be changed by replacing one dielectric sleeve to another larger or smaller cross-section. To change the cross section of the narrow isthmus you can also change one inner ceramic part to another, but the production of dielectric bushings cheaper and easier. The risk of damaging parts for the performance of repair work on the alleged lack of critical mechanical influences on them is minimal.

Conducted by the applicant's analysis of the prior art, including searching by the patent and scientific and technical information sources and identify sources that contain information about the equivalents of the claimed invention, has allowed to establish that the applicant had not discovered similar, characterized by signs, identical with all the essential features of the claimed invention. The definition from the list of identified unique prototype as most Lyskovo on essential features of the analog revealed the essential towards perceived by the applicant to the technical result of the distinctive features in the claimed device, set forth in the claims.

Therefore, the claimed invention meets the condition of "novelty".

To verify compliance of the claimed invention the term "inventive step", the applicant conducted an additional search of solutions in order to identify characteristics that match the distinctive features of the prototype of the characteristics of the claimed device. The search results showed that the claimed invention not apparent to the expert in the obvious way from the prior art because the prior art defined by the applicant, not the influence provided the essential features of the claimed invention transformations on the achievement of the technical result, in particular, the claimed invention does not provide for the following conversions:

- addition of known means of any known part (s), attached (connected) to it according to certain rules to achieve a technical result, in respect of which it is the effect of such additions;

- replacement of any part (s) of the other known means known part to achieve a technical result, in respect of which it is the effect of such a change;

- the exclusion of any part (element) means the simultaneous exclusion of its cash is a chiy functions and achievement with the usual result of such exclusion (simplification, weight, dimensions, material consumption, higher reliability, etc.);

- increasing the number of identical elements to enhance the technical result due to the presence in the vehicle is of such elements;

- execution of a known drug or its part (s) of a known material to achieve a technical result due to the known properties of this material;

- creation of tools, consisting of well-known parts, the choice of which and the relationship between them is carried out on the basis of known rules, recommendations and achievable technical result is due only to the known properties of the parts of this tool and the relationships between them.

The described invention is not based on the change of the quantitative characteristic (s), the submission of such evidence in the relationship or change its appearance. This refers to the case when the known fact of the influence of each of these features on the technical result and the new values of these characteristics or their relationship could be obtained from the known dependency relationships.

Therefore, the claimed invention meets the condition of "inventive step".

The invention is illustrated figure 3, which shows the current limiter containing dielectric sleeve 1 with an axial bore within which is freely inner ceramic part 2 in the form of a sphere strict geometrical dimensions, a narrow isthmus 3 in place of the cross-section of the inner ceramic part 2 on its diameter and the diameter of the dielectric sleeve 1. On the dielectric sleeve 1 on both sides are the contact pins 4 and 5, one of which is attached to the bellows 6. The internal cavity of the bellows 6, the dielectric sleeve 1 and the narrow isthmus 3 filled with liquid metal 7. Figure 4 shows a section a-a figure 3.

The operation of the device is as follows.

The current limiter is a liquid metal device that is in working condition it is filled with liquid metal and performs the function of switching the electric current and circuits. The circuit current passes from the contact pin 4 to pin 5 through a narrow isthmus 3. Open circuit occurs in the narrow isthmus 3 - place the smallest cross-section, which is located in the place of the cross-section of the inner ceramic part according to its diameter and the diameter of the dielectric sleeve. During the flow of short circuit current in the narrow isthmus of the current limiter portion of the liquid metal is heated to the boiling point and evaporation, which leads to the formation in the separation of the gas tube and the electric arc. The combustion process of the electric arc is accompanied by release of heat in the conductive channel, which leads to further heating of the liquid metal, su the greater its transition into a gaseous state and to increase the vapor pressure of the liquid metal in the closed volume of the current limiter. As is known, a pair of liquid metal have a large resistance, which leads to the quenching of the electric arc. Explosive increase in pressure is compensated by the expansion of the bellows 6. After arc extinction pair of metal condensed and under the action of the elastic force of the bellows back into the narrow isthmus 3. Damaged electrical circuit is separated from the network switching apparatus for a time, during a pause.

Thus, the above data confirm that the implementation of the use of the claimed device the following cumulative conditions:

the tool embodying the claimed device in its implementation, is intended for use in industry, namely in the field of electrical engineering;

- for the claimed device as it is described in the independent clause sets out the claims, confirmed the possibility of its implementation using the steps described in the application of tools and methods;

the tool embodying the claimed invention in its implementation, is able to achieve perceived by the applicant of the technical result.

Therefore, the claimed invention meets the condition of "industrial applicability".

The current limiter containing dielectric sleeve with an axial hole is m, damping site, filled with molten metal, and the contact pin, characterized in that it has an internal ceramic item in the form of a ball of the correct geometrical dimensions, and the narrow isthmus formed in place of the cross-section of the inner ceramic part according to its diameter and the diameter of the dielectric sleeve.



 

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Current limiter // 2254636

FIELD: electrical engineering; short-circuit protective gear.

SUBSTANCE: proposed liquid-metal current limiter designed for use in up to 0.4 kV power networks to protect power loads against short-circuit currents has insulating bushing with axial bore receiving internal loosely mounted ball-shaped ceramic part of strict geometrical dimensions, and easy-to-manufacture narrow neck disposed at cross-sectional area of internal ceramic part, along its diameter and diameter of insulating bushing. Either side of bushing mounts contact leads, bellows being attached to one of them. Inner cavity of bellows and that of insulating bushing, as well as neck are filled with liquid metal.

EFFECT: reduced risk of damage to bushing and ceramic part; enlarged functional capabilities due to ability of in-service variation of narrow neck section.

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Current limiter // 2614389

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to electric circuits protection devices, and can be used for electric equipment protection against short circuit currents. Current limiter contains capillary channels, filled with liquid metal, formed by bushing inner surface and located in it cylinder with cutouts on side surface along cylinder entire length. Cutouts on cylinder side surface have shape of cylinder cross section segment. Cutout shape allows to control cutting tool vertical feed only, simplifies technological process and increases current limiter functional capabilities.

EFFECT: technical result is simplification of technological process and improved functional capabilities of current limiter.

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