Electric contact connection lubricant, kit of parts for an electrical contact connection, transformer equipment, electrical contact network for railway and / or urban transport, method for stabilizing the transient resistance of a detachable electrical contact connection

Abstract

The invention relates to an electrical contact connection, including a kit of contact connection elements, as well as to a method for stabilizing the contact resistance of an electrical contact connection. The contact connection contains conductive contact elements, a threaded connection for pressing the contact surfaces of the conductive elements, a contact pressure stabilizer made of high-pressure sintered plates of a shape memory alloy, as well as functional grease for application to the contact surfaces of conductive elements, which is a mixture of plastic gel with the addition of microparticles made of a shape memory alloy.

Description

[0001] ELECTRIC CONTACT CONNECTION LUBRICANT, KIT OF PARTS FOR AN ELECTRICAL CONTACT CONNECTION, TRANSFORMER EQUIPMENT, ELECTRICAL CONTACT NETWORK FOR RAILWAY AND / OR URBAN TRANSPORT, METHOD FOR STABILIZING THE TRANSIENT RESISTANCE OF A DETACHABLE ELECTRICAL CONTACT CONNECTION

[0002] FIELD OF THE INVENTION

[0003] The claimed technical solution relates to the field of energy. In more detail, the claimed invention relates to a new metal alloy device that provides an electrical contact connection by controlling the threshold temperature of overheating, stabilizing the contact pressure and destroying oxide films. The new device with an improved electrical contact connection of the present invention can be used in the electric power, oil and gas industry, metallurgical, mining, chemical and other related industries as well as in transport, network and traction locomotives, substations, switchgear and other electrical installations. The new device with an improved electrical contact connection of the present invention is used in systems for generating, transmitting and distributing electric energy at electric voltage levels up to 1000 kV and higher.

[0004] The invention is directed to reducing the transient resistance of detachable electrical contact connections, stabilizing the resistance value, and to the possibility of direct connection of of connections of contact parts of copper, aluminum and their alloys, both in terms of installation, repair and maintenance of existing energy facilities, as well as for use in enterprises producing electrical equipment using functional intermetallics.

[0005] BACKGROUND OF THE INVENTIONThe key function of electrical contact connections is to create conditions for the flow of current through certain parts of the circuit by direct contact and tightening of specially formed conductors, with minimal losses and within the required time interval. The trouble-free operation of electrical wires and electrical equipment depends on the condition of the electrical contact connections. During operation, the contact connections are periodically heated and cooled by varying in time currents of the electrical load or short circuit. The processes of heating and cooling the contact connections lead to mechanical stresses in the contact parts, to accumulation of residual deformation, to reduction of the contact pressure, to an increase of the transient resistance and further to a heat increase in contact temperature at the same load currents. The process of overheating the contacts during prolonged operation is natural and objective from a physical point of view and can be changed only with additional means. Contact connections are the weakest parts of electrical systems. The main reason for the diminished their reliability is increase in the transient resistance over time between the elements of the connection. Unwanted oxide layers formed on the contact surface create excess electrical resistance, which can lead to damage of the contact system. Atmosphere humidity also affects the contact surface. Oxides, sulfides and other surface pollutants have higher electrical resistances than base metals. The high contact resistance between the contact elements causes an uneven distribution of electric currents over the surface of the contact parts, leading to excessive power losses at contacts, and therefore to an increase in temperature of the contact connection. It is found that the highest energy losses are at the area of connection at the ends of the contacts, where the contact temperature rises. It is this higher temperature that intensifies oxidation processes on the surface of the contacts and leads to a further increase in the contact resistance at the ends of the contacts.

[0006] Many factors affect the quality and life of contact connections.

[0007] Contamination with dust, humidity, coatings, current harmonics, accidental malfunctions in exploitation and higher temperatures are the main such factors. The volume of the electrical current capacity of the splint load is determined by the maximum temperature for which the splint is designed. This upper operating temperature limit is important because at the maximum operating temperature the velocity of surface oxidation of the contact materials in the air environment increases rapidly, which in the long run can lead to local overheating of theconnection. A way to improve the operation of the connection is to increase the contact surface. A constructive increase in the area of the connection, respectively, is known to increase heat transfer to the environment, but above certain sizes, this does not affect the operation of the electrical connection. An important factor that determines the of reliability a contact connection is the contact pressure force, which is normalized depending on the type of material and its hardness. Increasing the contact force of pressure leads to a decrease in the contact resistance, and hence to a decrease in temperature, but it is not desirable to exceed the specified value of the contact pressure, as it will mechanically damage the elements of the connection, and as a result will also lead to rising contact resistance.

[0008] In electrical networks and electrical equipment, a large number of contact connections of different kinds and types are used. The most common of these 30 are detachable screw-on or twist-on electrical contact connections. The efficient operation of electrical networks and electrical equipment largely depends on the reliability and efficiency of multiple detachable screw-on or twist-on electrical contact connections connecting individual sections of electrical networks.

[0009] A problem in the operation of the detachable contact connections affecting the reliability and efficiency of electrical networks and electrical equipment, is the uncontrolled and uncompensated increase in transient electrical 5 resistance, which leads to power losses, overheating of contact elements and can cause emergencies and even the occurrence of fires, circuit breakings and emergency shutdowns.

[0010] In summary, the factors that influence the increase in the transient electrical resistance and, as a consequence, the overheating of the detachable contact connections are:

[0011] - weakening of the contact pressure, for example in case of self-loosening of the connection as a result of vibrations;

[0012] - accumulation of residual deformation in the elements of the detachable contact connections during heating-cooling cycles, due to the use of materials with different coefficients of thermal expansion (current-carrying elements Al, Cu, etc., as well as Fe, from which material the fasteners are made - bolts, screws, nuts);- oxidation of contact surfaces, formation of dielectric oxide films due to the penetration of air and moisture with aggressive impurities into the space between the contact elements, which causes oxidation processes,

[0013] - decreasing of the contact zone due to the weakening of the contact force of pressure and the oxidation processes of the contact surfaces, and others (Fig.1 ).

[0014] A group of known technical solutions, such as the disclosures in patent publications RU74211U1, US9058729B2, US9748062B2, offer only monitoring of the temperature of the detachable contact connections. The sensor elements are made in different ways, for example as flexible stickers with color reversible and nonreversible thermal indicators, as well as indicators in the form of springs made of shape memory material or paraffin-based actuator. These known devices only indicate that a contact connection temperature has risen above a predetermined value, but do not fix the time of the adverse event, nor can they alleviate the state of the connection and 30 return it to normal operation.

[0015] There are also ways to reduce contact mechanical stress and provide a large effective contact surface area by applying a thin layer of electrically conductive or electrically neutral contact lubricants. Contact lubricants are known in the art, representing specially formulated greases and oils that improve the electrically conductive characteristics of electrically charged metal surfaces in switches and connectors. But these lubricants do not effectively prevent the formation of oxide layers. The process of oxidation of the contact parts takes place continuously during the operation of the electrical installations. With high humidity, aggressive environments and high temperatures of ambience, this process is much faster than under normal operating conditions.

[0016] It is known from the patent publication JP2001345017A conductive bonding layer for electronic boards, containing thermosetting or thermoplastic bonding resin in which are mixed a large number of fine conductive metal particles and twocomponent conductive casted metal particles containing a core in the form of bent staples or splices made from alloy with a shape memory effect, coated with another electrically conductive layer of alloy with a lower melting point. When heated during the application of the layer, the core elements straighten, stretch the shell of coated electrically conductive layer, and increase their area in contact with the fine metalparticles, resulting in improved conductivity. Such a conductive layer is not applicable for contact connections in the electric power industry, because during its application the layer hardens and the connection becomes non-detachable. In addition, the harmful oxide and contaminant layers in the contact connections obtained during the operation of the joints are not destroyed.

[0017] There are ways to protect detachable electrical contact connections, but some of them only reduce the negative impact of individual factors on the technical condition of the electrical contact connections and do not guarantee their reliability.

[0018] A detachable bolted contact connection (Dzektzer N.N., Vislenev Y.S., Multiampere contact connections. L .: Energoatomizdat. Leningrad. Otd-nie, 1987, 30 128 p.) is known, which contains current-carrying elements having contact surfaces, a bolt with a nut and a steel spring washer for squeezing the contact surfaces of the current-carrying elements. At the beginning of the operation of the contact connection, the steel spring washer ensures that the contact pressure is maintained within the nominal values, but practice shows that the pressure created by such a washer is not directly dependent of the temperature state of the detachable contact connection. In addition, it negatively affects the conductive elements, which are made of non-ferrous metals and are much softer than spring steel. Steel spring washers have a limited temperature range of operation up to 110°C, and of heatingelectrical contacts by short-circuit currents can lead to heating with a temperature of 200...250°C. In this case, steel spring washers lose their elastic properties and cause thermal destruction of the contacts.

[0019] Other detachable electrical contact connections are also known, in which the contact pressure is regulated with raising temperature. The electrical contact connections described below are of interest. For example, the detachable contact connection of the patent publication UA79134 C2 comprises current-carrying elements having contact surfaces and a threaded joint for squeezing the contact surfaces of the current-carrying elements, in this case a bolt with a nut, a plate made of alloy with effect of shape memory. The plate being placed between the contact surfaces of the contact elements, covering the entire area between the contact surfaces, which plate deforms with raising temperature and at the time of deformation the plate rubs on thecontact surfaces, destroys the partially formed oxide layers, reduces the contact resistance, leading to a drop in temperature and return of the shape of the plate to its original position.

[0020] Another close contact connection, disclosed in the patent publication UA3829 (U), also comprises current-carrying elements having contact surfaces and a threaded joint for squeezing the contact surfaces of the current-carrying elements, in this case a bolt with a nut, as well as having two washers placed under the head of the bolt and the nut, which washers are made from alloy with shape memory effect. One washer has a final temperature for recovery the initial shape below the minimum ambient temperature (it when heatedexhibits the shape memory effect). The other washer is a spring washer (which exhibits the effect of superelasticity when deformed) with a temperature at the beginning of the recovery of the shape higher than the maximum possible ambient temperature, thus compensating for the mechanical stresses in the contact parts.

[0021] It is also known from the other patent publication RU2091932C1 an electrical contact connection, comprising current-carrying contact elements, a threaded joint, in this case a bolt with a nut, for pressing the current-carrying contact elements and at least one contact pressure stabilizer in the form of a disc spring washer connected to the bolted connection. The stabilizer is made of an alloy with an effect of superelasticy, which improves the contact pressure.

[0022] Another prior art disclosure is described in the patent publication UA57110C2. Disclosed is a contact connection comprising current carrying contact elements, a threaded joint, in this case a bolt with a nut, for pressing the cunentcarrying elements, as well as at least one contact pressure stabilizer in the form of a disc spring washer connected to the bolted connection. The stabilizer is made of an alloy with a shape memory effect with an initial shape recovery temperature higher than the maximum possible ambient temperature.

[0023] The known inventions of detachable threaded contact connections cannot reduce the transient electrical resistance completely, as they rely only on the squeezing and pressing force.

[0024] In addition, there is a known solution according to the international publication W02023 / 060325, which discloses an electrical contact connection comprising at least two conductive elements having contact surfaces, at least one threaded connection having athreaded element, and at least one nut for compressing the contact surfaces of the conductive elements. The known contact connection also comprises a lubricant for applying to the contact surface of at least one of the at least two conductive elements. The .lubricant is a mixture containing a plastic gel with the addition of shape memory alloy microparticles.

[0025] The shape memory alloy microparticles added to the plastic gel have a structure of at least one of: pointed tips, regions or edges. Also, the electrical contact connection comprises at least one contact pressure stabilizer made of a shape memory alloy, designed to be positioned at one end of the threaded element and in contact with one conductive element.

[0026] This solution has insufficiently high technical characteristics, in particular, when used in a high voltage network reaching 1000 V, at which the destruction of oxide films is an urgent problem. In known analogs, functional grease contains a powder of a shape memory alloy with a copper base. Studies have shown that when in contact with aluminum contact parts, a galvanic effect occurs, which leads to an increase in the transient resistance of the contact connection. The formation of a galvanic couple can be eliminated by applying silver powder to the surface. To ensure the reliability and efficiency of the operation of the detachable contact connections the solution should be comprehensive, neutralizes the basic factor and allowing for the neutralization of the main factors and allowing to neutralize a greater number of negative factors for a long time.

[0027] SUMMARY OF THE INVENTION

[0028] It is an object of the present invention to provide an electrical contact connection with increased efficiency, reliability and durability, which provides a reduction of the transient electrical resistance, and a reduction of the total operating losses of the electrical installations.

[0029] The technical task is achievedby that the electrical contact connection includes at least two conductive elements having contact surfaces, at least one threaded connection having a threaded element, and at least one nut for compressing the contact surfaces of the conductive elements. According to the invention, the electrical contact connection further comprises a lubricant for applying to the contact surface of at least one of the at least twro conductiveelements.

[0030] The lubricant is a mixture of containing a plastic gel with the addition of shape memory alloy microparticles, wherein the shape memory alloy microparticles added to the plastic gel in an amount of 25- 30% are coated with a layer of silver 0.5-1 pm and have a structure of at least one of the following: pointed tips, regions or edges.

[0031] The electrical contact connection also contains at least one contact pressure stabilizer made of a package of pressure-sintered plates of a shape memory alloy, designed to be positioned at one end of the threaded element and in contact with one conductive element.

[0032] The electrical contact connection according to a preferred embodiment further comprises a spring washer made of an intermetallic alloy, which is made to be positioned at the other end of the threaded element and to contact the contact surface of another conductive element with a superelastic effect.

[0033] In addition, the invention provides that the electrical contact connection additionally contains at least one temperature indicator made of a shape memory alloy, made with the possibility of positioning and contacting the elements of the contact connection.

[0034] This problem is solved by the fact that the lubricant for the above electrical contact connection is a mixture of a plastic gel with added shape memory alloy particles, wherein the added shape memory alloy particles have a structure of at least one of: pointed tips, regions or edges.

[0035] The particle size is preferably aro und 10 pm, and the plastic gel is a neutral or electrically conductive lubricant.

[0036] In addition, the problem is solved by the fact that the kit of parts for the above electrical contact connection contains at least one threaded element, at least one nut, at least one contact pressure stabilizer and at least one element containing the above-mentioned lubricant.

[0037] In addition, the parts kit contains at least one spring washer made of the intermetallic alloy mentioned above and / or at least one temperature indicator made of the shape memory alloy mentioned above.

[0038] The task is also solved by the fact that the transformer equipment contains at least one electrical contact connection mentioned above.In addition, the problem is solved by the fact that the electrical contact network for rail and / or urban transport contains at least one electrical contact connection, as mentioned above.

[0039] In addition, the technical problem is solved by the fact that the method of stabilizing the transient resistance of a detachable electrical contact connection includes the step of scratching one or more contaminating layers formed during the operation of the contact connection on the contact surfaces with a lubricant applied between the contact surfaces of the conductive elements of the contact connection. In this case, the lubricant is a mixture containing a plastic gel with added particles of a shape memory alloy. The particles of the shape memory alloy added to the plastic gel in an amount of 25-30 %, coated with a layer of silver of 0.5-1 pm, have a structure of at least one of the following: pointed tips, regions or edges for scratching and destroying contaminating layers formed during the operation of the contact connection on the contact surfaces.

[0040] It is provided that the method additionally includes the steps of adjusting the seal between the conductive elements of the contact connection and maintaining the dense pressure to the nominal value at an accidental or systematic decrease in contact pressure and an increase in the temperature of the contact connection using a spring intermetallic washer made of an alloy with a superelastic effect, which has the ability to contact one of the conductive elements and / or using a contact pressure stabilizer made of an alloy with a shape memory effect, made of a The above inventions provide transformer equipment and / or a catenary from the electrical grids that are more reliable and efficient with reduced maintenance costs. In particular, an increase in the percentage of powder (coated with a thin layer of silver 10-25 microns) to 25-30% ensures not only mechanical destruction of oxide films, but also acts as a transition layer when connecting aluminum and copper contact parts. The presence of a 25-30% powder volume content in the functional grease, filling in the irregularities on the contact parts, increases the area of the contact pads and, accordingly, reduces the transient resistance of the contact connection. In addition, studies have shown that the presence of a 25-30% volume content of shape memory alloy powder in functional grease creates a layer between the contact parts, which, when the pressure in the contact connection decreases, the transient resistance and contact temperature increase during operation, restores the shape in theintercontact space and reduces the transient resistance and temperature of overheated electrical contact areas.

[0041] In addition, the stabilizer has increased strength and the ability to generate a higher reaction force with the same geometric dimensions by 27-30% compared to its analogues. The technical solution improves the reliability of the stabilizer and reduces the consumption of shape memory alloy for its manufacture by 18% due to the fact that the stabilizer is made of a package of high-pressure sintered shape memory alloy plates.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Fig. 1 shows stabilizer with prior art known from patent application W02023 / 060325 Al.

[0044] Fig. 2 shows stabilizer according to the proposed technical solution.

[0045] Fig. 3 shows a fragment of the electrical contact connection in the general view of the fragment (a)) and the cross-section of the fragment (b)).

[0046] Fig. 4 shows the electrical contact connections of of the collapsible type: a - connection ofntwo flat bars; b - connection of two lugs; c - connection of a flat bar and a lug; c - connection of a lug and a power transformer input pin.

[0047] Fig. 5 shows the thermomechanical characteristics of the contact pressure stabilizers made of a homogeneous strip and a strip with two sintered layers of a shape memory alloy.

[0048] In Fig. 6 are the results of transient resistance measurements in the contact connections with lubricant and without lubricant.

[0049] DETAILED DESCRIPTION OF THE INVENTION

[0050] The present invention is illustrated by the accompanying drawings, in which a preferred embodiment of the contact compound applicable to general use is shown.

[0051] Fig. 1 shows a contact pressure stabilizer in an electrical contact connection known from prior art document W02023 / 060325 Al, which is a conical washer made of a shape memoryalloy made by cutting from a rolled strip made from a single alloy ingot.

[0052] However, further studies in the laboratory and in the field have shown that it is possible to create stabilizers with higher mechanical strength and higher reactive force.

[0053] Figure 2 shows a preferred embodiment of a contact pressure stabilizer in an electrical contact connection. The proposed solution is characterized by the presence of more than one layer of material. This is due to the fact that the stabilizer is made of a package of high-pressure sintered plates of a shape memory alloy.

[0054] In the general view of a fragment of an electrical contact connection, Figure 3a shows the combination of the contact parts to form contact regions 2 for the passage of electric current. Figure 3b shows a cross-section of the contact connection. The combination of two contact parts 1 is characterized by a relief structure of the surface of each contact part. In the space formed by the unevenness of the surfaces of the contact joints, during the operation of the electrical contact joint, a film of oxides is formed 4 , which prevents the passage of electric current. Therefore, it is necessary to break this film of oxides 4 to ensure reliable passage of electric current. As can be seen in FIG. 3b, the lines of electric current in the contact connection 3 pass through the contact pads on the surface of the contact part 2.

[0055] The powder particles are a very fine fraction of intermetallic particles, such as very fine chips derived from an intermetallic alloy with a shape memory effect. Preferably, the plastic gel lubricant is a neutral contact lubricant such as SOLIDOL, CIATIM, etc., and the added intermetallic particles are in the range of 7-15% (by volume of lubricant) and have a size of approximate 1 y 10 p m. In this case, the particles are obtained by scraping a piece of intermetallic material with diamond powder abrasive tools, but they can be obtained by any other method known in the art. The transformation temperature of the added intermetallic particles is, for examp le, in the range of about 50°C to about 60 °C . Experi mentally it was found ,that an increase in the percentage of powder (coated with a thin layer of silver of 0.5-1 microns) to 25-30% ensures not only mechanical destruction of oxide films, but also acts as a transition layer when connecting aluminum and copper contact parts. The service life of the contact lubricant is about 12 months.

[0056] Fig. 4 shows a bolted electrical connection according to the invention. The claimedtechnical solution can be used, in particular, for the following types of electrical contact connections of the collapsible type: a - connection of two flat bars; b - connection of two lugs; c - connection of a flat bar and a lug; c - connection of a lug and a power transformer input pin.

[0057] In general, the preferred embodiment of a contact connection for stabilizing the transient electrical resistance of a connection containing elements made of intermetals according to the is explained as follows. A threaded connection connecting the contact elements 1 by means of a bolt. An intermetallic temperature indicator is mounted on the contact surface of the single contact element 1 , on which an intermetallic stabilizer is mounted. The temperature indicator and the stabilizer are made of an alloy with a shape memory effect. An intermetallic spring washer, made of an alloy with a superelasticity effect, is mounted on the contact surface of another contact element.

[0058] A functional electrically conductive intermetallic grease is used between the contact surfaces of the two contact elements 1. In the case of periodic heating of the contact surfaces as a result of an electrical load or short-circuit currents, intermetallic particles destroy the dielectric oxide layers on the contact surfaces and thus stabilize the effect of contact electrical resistance. The mechanism of layer destruction is based on the thermodynamic properties of shape memory intermetallic compound particles, which change their shape under the influence of temperature, move relative to the contact surface, scratch the harmful layer and thus destroy the oxide films.

[0059] The intermetallic stabilizers are manufactured with the parameters required to optimize the contact pressure for the respective bolted connection size. The contact pressure also depends on the design and materials of the contacting elements. For example, a the range of 40.0 + / - 2.0 Nm, while for copper conductors a contact pressure in the range of 64.0 + / - 3.0 Nm is desirable. The stabilizer and spring washer can be made with the primary shape of tapered rings. For example, for preferred contact pressure for an Ml 2 threaded connection and aluminum conductors is in bolted connections with Ml 2 thread, stabilizer and washer can have an outer diameter d2 equal to 24 + / - 0.5 mm, an inner diameter dl equal to 13.5 + / -0.5 mm, a thickness of the washer equal to 2.5 + / - 0.5 mm, and a height of the washer equalto 3.6 + / - 0.5 mm. The material of the spring washer has a shape memory effect, for example, a Cu-XY based multielement compound, where Y and / or X are selected from elements of groups II - VI of the periodic table. One of the exemplary compositions is Cu - 83.0%, Al - 13.0% and Mn - 4%, which at a temperature of -35 oC has a shape memory effect, and in the temperature range above 15 oC provides a superelastic effect. The material of the stabilizer may be, but is not limited to, copper-based multielement compounds such as Cu-Zn-Al, Cu-Al-Mn, Cu-Ni- Al or Cu-Al-Zn, whose memory effect is manifested at positive temperatures, for example, in the range from +15 oC to 150 oC, as in +40 oC, where the superelastic effect is not manifested.

[0060] The general operation of the stabilizer is explained as follows. At the initial moment of actuation of the contact connection or after repair work, the stabilizer is deformed to a flat shape by the pressure of the bolted connection. After the bolted connection is loosened for external accidental or undesirable reasons and the contact surfaces do not provide tight contact or after the formation of contaminating layers due to environmental conditions, the contact area decreases and the temperature rises above the transformation temperature of the stabilizer material. The stabilizer made of high- pressure sintered plates intermetallic with a shape memory effect begins to return to a conical shape, and the contact pressure returns to its original values. The thermomechanical characteristics of the intermetallic stabilizer during cyclic heating and cooling are shown in Fig. 5. The value of the operating temperature of the stabilizer depends on the ratio of the components from which the alloy (intermetallic) for the stabilizer is made. The technology for the preparation of intermetallics with a given threshold operating temperature is described in application PCT / BG2020 / 000017. For example, intermetallic stabilizers can be easily produced with an operating temperature of (-10), 30, 50 °C or other values.

[0061] Lubricant applied between contact surfaces is a mixture of gel and lubricant binder in which particles of intermetallic powder are evenly dispersed. The applied layer of functional lubricant has an orderliness of 0.2-0.3 mm.

[0062] The particlespowder are a very fine fraction of intermetallic particles, for example, very fine chips obtained from an intermetallic alloy with a shape memory effect. Preferably, theplastic gel lubricant is a neutral contact lubricant such as SOLIDOL, CIATIM, etc., and the added intermetallic particles are in the amount in the range of 25-30% (by volume of lubricant) and have a size of approximately 10 pm. The particles in this case are obtained by scraping a piece of intermetallic material using abrasive tools with diamond powder, but they can be obtained by any other method known in the art. The transformation temperature of the added intermetallic particles is, for example, in the range of about 50°C to about 60°C.

[0063] The following is Table 1, which shows the resistance measurements of the contact connection with the transient resistance obtained as a result of experimental studies. Graphically, this Table 1 is reproduced in Fig. 6

[0064] Table 1.

[0065]

[0066] Continuation of Table 2

[0067]

[0068] From Table 1 and Fig. 6, it can be concluded that the shape memory alloy powder has a positive effect on the transient resistance of the contact joint. After 100 heating-cooling cycles of the contact joints of rectangular aluminum tires, the change in the transient resistance of the contact joint with the lubric ant occurred in the ran ge f rom 19.3 to 24.2 p , which can beconsidered acceptable.

[0069] In the contact joint without lubricant, the change in transient resistance ranged from 24.1 to 76.2 p . The re was an increase in the transient resistance by almost three times, which certainly worsens the condition of the contact - an increase in temperature and acceleration of chemical aging of the contact.

[0070] Although the description above contains many specifics, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus, the scope of this invention should be determined by the appended claims and their legal equivalents.

Claims

CLAIMS1. An electrical contact connection comprising at least two currentcarrying elements having contact surfaces, at least one threaded joint having a threaded element and at least one nut for squeezing the contact surfaces of the current-carrying elements, characterized in that:- it further comprises a lubricant for applying to the contact surface of at least one of the at least two current-carrying elements;- the lubricant is a mixture containing a plastic gel with added microparticles of an alloy with a shape memory effect;, wherein the microparticles of the shape memory alloy added to the plastic gel in an amount of 25-30 % are coated with a layer of silver 0.5-1 pm and have a structure of at least one of the following: pointed tips, regions or edges,- at least one contact pressure stabilizer made of a package of pressure-sintered plates of a shape memory alloy, designed to be positioned at one end of the threaded element and in contact with one conductive element.

2. An electrical contact connection according to claim 1, characterized in that it further comprises a spring washer made of an intermetallic alloy, which is made to be positioned at the other end of the threaded element and in contact with the contact surface of another conductive element with a superelastic effect.

3. The electrical contact connection according to claim 1 , characterized in that it further comprises a spring washer (5) made of intermetallic alloy capable of being positioned at the other end of the threaded element (14) and for contact with a contact surface of another current¬ carrying element (1), wherein the intermetallic alloy is with an effect of superelasticity.

4. The electrical contact connection according to claim 1, characterized in that it further comprises at least one temperature indicator (3) made of an alloy with a shape memory effect, having the possibility of positioning and contact with the elements of the contact connection.

5. The lubricant according to claim 4, characterized in that the particle size is approximately 10 pm.

6. The lubricant according to claim 4, characterized in that the plastic gel is a neutral or electrically conductive lubricant.

7. A kit of parts for an electrical contact connection according to claim 1, comprising atleast one threaded element, at least one nut, at least one contact pressure stabilizer and at least one element containing a lubricant according to claims 4-6.

8. The kit of parts according to claim 7, further comprising at least one spring washer made of the intermetallic alloy according to claim 2 and / or at least one temperature indicator made of the shape memory alloy according to claim 4.

9. Transformer equipment, characterized in that it contains at least one electrical contact connection according to claims 1-4.

10. An electrical contact network for rail and / or urban transport, characterized in that it contains at least one electrical contact connection according to claims 1 to 4.

11. A method for stabilizing the transient resistance of a detachable electrical contact connection, characterized in that:- includes the step of scratching one or more contaminating layers formed during the operation of the contact connection on the contact surfaces by means of a lubricant applied between the contact surfaces of the conductive elements of the contact connection;- lubricant is a mixture containing plastic gel with added particles from a shape memory alloy; and- particles of the shape memory alloy added to the plastic gel in an amount of 25-30 %, coated with a layer of silver 0.5-1 pm, having a structure of at least one of: pointed tips, regions or edges for scratching and breaking down contaminating layers formed during the operation of the contact joint on the contact surfaces.

12. Method according to claim 11, characterized in that it further comprises the steps of adjusting the seal between the conductive elements of the contact connection and maintaining the tight pressure to the nominal value when the contact pressure is accidentally or systematically reduced and the temperature of the contact connection is increased by means of a spring intermetallic washer made of an alloy with a superelastic effect, having the possibility of contacting one of the conductive elements and / or by means of a contact pressure stabilizer made of an alloy with a shape memory effect, made with the possibility of contacting another conductive element.

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