ELECTRICAL POWER OUTLET FOR DETACHABLE CONNECTION WITH AN ELECTRICAL POWER PLUG AND ELECTRICAL POWER COUPLING CONSISTING OF SUCH A POWER OUTLET AND AN ASSOCIATED ELECTRICAL POWER PLUG
Patent Information
- Authority / Receiving Office
- MX · MX
- Patent Type
- Patents
- Current Assignee / Owner
- FRONIUS INT GMBH
- Filing Date
- 2025-01-17
- Publication Date
- 2026-05-19
Smart Images
Figure MX433788B0
Abstract
Description
[0001] Power socket for detachable connection with a power plug and power coupling consisting of such a power socket and an associated power plug
[0002] The invention relates to a power socket for detachable connection to a power plug, with a base body made of electrically conductive material with a bore for receiving a substantially cylindrical bolt of the power plug and with a device for connection to a power cable, wherein a helical groove for receiving a locking lug of the power plug is arranged in the base body, wherein the base body has a sleeve with the helical groove and a receptacle for the sleeve.
[0003] Furthermore, the present invention also relates to a power coupling consisting of such a power socket and an associated power plug.
[0004] The term "essentially cylindrical" is intended to clarify that the bore in the base body of the power socket as well as the bolt of a matching power plug may also deviate slightly from the rotationally symmetrical shape and, for example, be slightly eccentric.
[0005] Such power sockets, together with matching power plugs, represent power couplings designed to transmit high currents of up to several hundred amperes. For example, such power couplings are used in welding systems to conduct high welding currents from the welding power source to the welding torch and to the workpiece. The standard DIN EN 60974-12 "Plug-in connectors for welding cables" exists for these connections, which are commonly used in welding technology. However, such power sockets can also be used in other applications, such as photovoltaic systems or battery chargers, as part of corresponding power couplings to transmit the direct current from solar modules or the charging current for charging batteries.
[0006] In welding systems, plugs from DINSE Ges. m. b. H. are very often used for power cable couplings and hose package couplings. These are known to experts in the field of welding technology as so-called DINSE® plugs, DINSE® sockets or DINSE® connectors. With the DINSE® connector, a plug with a locking nose is screwed into a socket with a helical groove with an angle of rotation of approx. 270° and a pitch of around 4 mm per 360°. The thread-like interaction between plug and socket results in a certain pre-tension force or tightening torque of the connection or a corresponding axial force, which holds the plug connection in its connected state. The plugs and sockets have different cross-sections depending on the current intensity.
[0007] In the case of shielding gas and plasma welding systems, the shielding gas or plasma-capable medium is also guided through appropriate channels in the centre of the power coupling.
[0008] The relatively steep pitch of the helical groove in state-of-the-art power sockets, together with a short pre-tension length (the length of the plug connection that runs from the electrical contact surface between the power plug and power socket to the locking lug on the power plug) and a high pre-tension area (the area of the power socket or the bolt cross-section of the power plug that is loaded with a force) of the connection result in an extremely steep pre-tension characteristic curve, i.e. a high gradient of the force-displacement curve of the plug connection. This means that the energy required to release the connection, i.e. to release the plug from the socket, is very low and even temperature fluctuations or vibrations can lead to unintentional release of the connection. If the connection has lost the pre-tension force, the contact resistance of the power coupling increases rapidly.When correspondingly high currents are transmitted, this can lead to local overheating at the connection between the power socket and power plug, which in turn can cause parts of the power cable and the power coupling to oxidize. If the power coupling is oxidized, the operating temperatures rise, which can lead to the destruction of the plastic parts of the power plug and power socket, the connected power cable and the connected device, for example the welding power source. If the prescribed temperature values are significantly exceeded, injury to the operating personnel cannot be ruled out. In addition, an increase in the contact resistance of the power coupling can also have a negative effect on the respective process, for example the welding process, and can even lead to defective production.
[0009] In order to improve the contact resistance of the power coupling, power sockets have been further developed by having a spring-loaded locking nose on the plug which significantly increases the release energy or the release torque of the connection. One such power coupling is described, for example, in WO 2016 / 128557 A1, wherein the power plug of the power coupling has a displaceably mounted locking bolt which is held in a basic position by a spring device. In addition to the greater design effort and the resulting higher manufacturing costs, a disadvantage of this plug is that due to the design in the center of the power plug, a bore or cavity in the axial direction for guiding a gas cannot be realized, or only easily.Finally, it is also disadvantageous that the solution complexity is located in the power plug, which is usually exposed to harsher environmental conditions than the socket and is also located in the more price-sensitive part of the power coupling.
[0010] DE 10 2018 007 686 A1 describes a welding power cable for connection to a welding power source, whereby the risk of torsion-related unintentional detachment of the power plug from the power socket is reduced by a bayonet element with a bayonet locking device.
[0011] FR 2 270 695 A1 discloses a power socket of the type in question, wherein the base body has a sleeve with the spiral-shaped groove and a receptacle for the sleeve.
[0012] The object of the present invention is to create an above-mentioned current socket for couplings for transmitting high currents of up to several hundred A, as can occur, for example, in welding systems, photovoltaic systems, or battery chargers, which ensures the lowest possible contact resistance and thus optimal current transfer and prevents or at least minimizes the risk of local overheating of the current socket and the power plug due to impermissibly high current densities. The current socket should be as simple and cost-effective to manufacture as possible and also allow the conduction of a protective gas or the like in the center. Disadvantages of known current sockets should be avoided or reduced.
[0013] The object of the invention is achieved by an above-mentioned current socket, wherein the helical groove has at least two regions with a positive pitch, and at the end of each region with a positive pitch, regions with a negative pitch are arranged to form a respective locking step, wherein the receptacle is made of metal or a metal alloy with a covering of electrically insulating material and the sleeve is made of a harder material than the receptacle. By separating the base body into at least two parts, the sleeve with the helical groove and a receptacle for the sleeve, the parts can be made of different materials and further advantages can be achieved, which are described further below.By providing the helical groove in the sleeve of the power socket with at least two areas with a positive pitch and arranging areas with a negative pitch at the end of each area with a positive pitch, the operator can be given haptic feedback when the respective locking step is reached. In addition, this makes it possible to achieve a higher loosening torque than the tightening torque, which makes it more difficult for the power coupling to be accidentally released. By providing at least two locking steps, even a worn power plug can still be securely locked in the power socket by selecting the second or further locking step, i.e. after reaching the first locking step, the plug is turned further relative to the power socket and is then securely held in the next or next but one locking step.Due to the improved resulting connection of the power coupling, the contact resistance can also be reduced, thus reducing the risk of destruction or impairment of the power socket, the power plug, the power cable, or the connected devices, as well as the risk of injury due to excess temperature and negative influences on the respective process, such as the welding process. The measures on the power socket allow connection with conventional power plugs, such as the DINSE® plugs mentioned above, and do not require the replacement of the plugs of conventional components, such as welding components.A further advantage of the present current socket is that the space around the central axis of the current socket can be kept free of structural measures, as a result of which a bore or cavity can easily be provided in the center of the current socket, for example for guiding a shielding gas, a plasma-capable medium, a welding wire or the like. Because the technical features for achieving the object according to the invention are arranged in the current socket, the costs required for this can be shifted from the more cost-sensitive part of the power coupling, the power plug, to the current socket. In addition, the current socket is usually arranged in the respective device, for example in the welding power source, and is less exposed to harsh environmental conditions than the power plug. But the necessary structural measures on the current socket can also be implemented relatively easily and inexpensively.
[0014] If a spring element for spring-loaded mounting of the sleeve is arranged in the holder for the sleeve of the base body in the axial direction of the holder of the base body, the connection between the power socket and a corresponding power plug can be further improved and the contact resistance of the power coupling can be reduced. The spring force can increase the loosening torque even further compared to the tightening torque of the plug connection and thus further reduce the risk of the power plug accidentally coming loose from the power socket. Thermal cycles, vibrations and impacts can no longer loosen the plug connection. By selecting the appropriate spring element, the contact force of the power connection and thus the contact resistance can be influenced. The force acting on the contact surface in each locking position can be adjusted using the spring element.The force acting on the contact surface is 5 to 50 N / mm. 2 preferred .
[0015] According to one feature of the invention, the spring element is formed by at least one wire spring washer. Such a wire spring washer can be manufactured very cost-effectively using a corrugated flat wire and can be arranged in the power socket in a particularly space-saving manner without requiring the central area of the socket, thus remaining available for conducting a protective gas or the like.
[0016] Advantageously, the spring element is formed by two wire spring washers and a spacer ring arranged between the wire spring washers. The spacer ring prevents the spring deflection of the wire spring washers arranged on either side from being reduced due to the wire spring washers rotating relative to each other, thus allowing the full spring force of the wire spring washers to be utilized.
[0017] Ideally, the sleeve has positioning elements, particularly axial locking lugs, to prevent rotation relative to the base body of the power socket. Such positioning elements on the sleeve are easy to implement and do not significantly increase manufacturing costs.
[0018] The holder for the sleeve of the base body of the power socket can consist of two parts that can be connected to one another. This allows the power socket to be assembled very quickly and easily by simply placing the necessary components, the sleeve and any spring elements, in the designated places on the parts of the holder of the base body of the power socket and then connecting the parts to one another. The two parts of the holder of the base body are preferably connected to one another using a press fit. Alternatively, the parts of the holder of the base body can also be removably connected to one another, for example using a screw connection with a left-hand or right-hand thread.
[0019] The base body holder can be made in particular of steel or a steel alloy or of brass or a brass alloy.
[0020] The sleeve of the power socket is preferably made of steel or a steel alloy. This has the advantage that wear occurs primarily on the softer power plug and not on the harder sleeve of the power socket. The holder of the base body has a flat end face for contacting to ensure optimal current transfer to the power plug. The flat design of the end face of the holder enables a uniformly low contact resistance to be achieved over the entire contact surface. This prevents areas on the contact surface with higher contact resistance, which could lead to local overheating due to particularly high current densities. If a protective gas or similar is passed through the power socket, the area around the central axis is left out and the end face is therefore preferably annular.
[0021] To improve current transfer, the end face of the base body's receptacle can be coated, for example, with a silver coating. Zinc or gold coatings are also possible for low contact resistance. Phosphate coatings, only in combination with other chemicals, protect the contact surface from corrosion.
[0022] According to one feature of the invention, the groove in the sleeve extends over a rotation angle of 90° to 270°. Such rotation angles are suitable for handling the power coupling.
[0023] The pitch of the positive pitch areas of the groove is ideally between 1 mm and 8 mm per 360°. These values are suitable for a suitable connection of the power socket to a matching power plug with the locking lug. The pitch of the positive pitch areas of the helical groove does not necessarily have to be constant, but can also be graduated, for example, rising or falling.
[0024] The pitch of the regions of the groove with a negative pitch for forming the locking steps is between 0.1 mm and 20 mm, preferably between 1 mm and 20 mm, particularly preferably between 5 mm and 20 mm per 360 °. By providing the regions with a negative pitch, the loosening torque can be increased even further compared to the tightening torque and the haptic feedback to the user when reaching the locking steps can be improved. As already mentioned above for the regions with a positive pitch, the pitch of the regions of the helical groove in the sleeve with a negative pitch can also be graduated.
[0025] According to a further feature of the invention, the helical groove can also have regions with no or no significant gradient after the regions with a negative gradient. Grading between the regions with a negative gradient and the regions with no gradient can achieve a smooth transition between these regions of the helical groove. Such transitions can positively influence the user's haptic perception.
[0026] In the simplest case, the device for connecting to a power cable can be a screw connection. This represents a simple and cost-effective implementation of the connection between the power cable and the power socket.
[0027] If the base body of the power socket has a through-hole or similar passage in the axial direction for conducting a shielding gas or similar material, a shielding gas or plasma-capable medium can be conducted through the current contact. Instead of a rotationally symmetrical hole, a differently shaped cavity can also be provided in the base body's axial direction for conducting the shielding gas or similar material.
[0028] The object of the invention is also achieved by a power coupling comprising a power socket described above and an associated power plug with a substantially cylindrical bolt. For the advantages achieved thereby, reference is made to the above description of the power socket.
[0029] If the sleeve of the power socket is made of harder material than the cylindrical bolt of the power plug, wear occurs preferentially on the softer power plug and not on the harder sleeve of the power socket.
[0030] The present invention is explained in more detail with reference to the accompanying drawings. In these drawings: Fig. 1 shows a power coupling consisting of a power socket and a power plug according to the prior art in a separated state;
[0031] Fig. 2 is a sectional view of a prior art power coupling according to Fig. 1 with connected power plug and power socket;
[0032] Fig. 3 is an exploded view of a power socket designed according to the invention;
[0033] Fig. 4A to 4D show detailed views of the sleeve of an embodiment of a power socket designed according to the invention;
[0034] Fig. 5 is a sectional view of a power socket constructed according to the invention;
[0035] Fig. 6 is a sectional view of a power coupling with the power plug not yet engaged in the power socket;
[0036] Fig. 7 shows the sectional view through the power coupling according to Fig. 6 with the power plug locked into the power socket;
[0037] Fig. 8 shows a force-displacement preload diagram of a power coupling with a power socket designed according to the invention compared to a power coupling with a conventional power socket; and
[0038] Fig. 9 shows the contact resistance and the power loss of a current coupling with a current socket designed according to the invention compared to current couplings with conventional plug connections.
[0039] Fig. 1 shows a power coupling 50 comprising a power socket 1 and a power plug 30 according to the prior art in a separated state. The power plug 30 has, in addition to a base body (not described in more detail), appropriate insulation and a device for connecting to the power cable 40, a substantially cylindrical bolt 31 made of electrically conductive material with a locking lug 32. The power socket 1 for the detachable connection to the power plug 30 has a base body 2 made of electrically conductive material with a bore 2' for receiving the bolt 31 of the power plug 30. The power socket 1 also has a device 4 (not described in more detail) for connecting to the power cable 40, for example a screw connection (see Fig. 2). In the base body 2 of the power socket 1 there is a spiral groove 5 for receiving the locking lug 32 of the power plug 30.To connect the power plug 30 to the power socket 1, the essentially cylindrical bolt 31 of the power plug 30 is inserted into the bore 2' of the base body 2 of the power socket 1 such that the locking lug 32 engages in the groove 5. The power plug 30 is then rotated relative to the power socket 1 according to the course of the helical groove 5 in the base body 2 of the power socket 1 (not shown). Nevertheless, the loosening torque is usually low, preventing the power plug 30 from being accidentally detached from the power socket.
[0040] 1 of the power coupling 50 is likely. The risk of loosening is increased by temperature fluctuations or mechanical forces acting on the parts of the power coupling 50. The increase in contact resistance that occurs when the connection is loosened can lead to local overheating of the power plug 30, the power socket 1 and / or the power cable 40 and to the destruction of parts of these components. Although the situation can be improved, for example, by a spring-loaded locking lug 32, unintentional loosening of the plug connection cannot be ruled out.
[0041] Fig. 2 shows a sectional view through a prior art power coupling 50 according to Fig. 1 with a connected power plug 30 and power socket 1. Here, it can be seen how the locking lug 32 on the essentially cylindrical bolt 31 of the power plug 30 projects into the helical groove 5 in the base body 2 of the power socket 1. In addition, the device 4 for connecting to the power cable 40 in the power socket 1 can be seen in the form of a screw connection 16. The power socket 1 has a sheath 13 made of electrically insulating material.
[0042] Fig. 3 shows an exploded view of a power socket 1 designed according to the invention. The power socket 1 has a base body 2 made of electrically conductive material with a sleeve 3 with the helical groove 5 and a receptacle 3' for the sleeve 3. In the illustrated embodiment, the receptacle 3' for the sleeve 3 consists of two interconnectable parts 11, 12. The parts 11, 12 of the receptacle 3' of the base body
[0043] 2 are formed, for example, from brass or a brass alloy, and have a casing 13 made of electrically insulating material (not shown here). The sleeve 3 is preferably formed from a harder material than the receptacle 3'11, for example from steel or a steel alloy.
[0044] The substantially cylindrical sleeve 3 serves to receive the substantially cylindrical bolt 31 of the power plug 30 (not shown). To prevent rotation of the sleeve 3 relative to the receptacle 3' of the base body 2, positioning elements 9, in particular axial locking lugs 10, are arranged on the sleeve 3, which protrude into corresponding recesses 18 in the part 11 of the receptacle 3' of the base body 2. The device 4 for connecting to a power cable 40, for example a screw connection 16, is not shown in detail. According to the invention, a helical groove 5 for receiving the locking lug 32 of the power plug 30 is arranged in the sleeve 3, wherein the helical groove 5 has at least two regions a, c with a positive pitch, and at the end of each region a, c with a positive pitch, regions b, d with a negative pitch are arranged to form a respective locking step (see Fig. 4A).
[0045] Optionally, a spring element 6 can be arranged in the base body 2 for resiliently supporting the sleeve 3 in the axial direction X of the receptacle 3' of the base body 2. In the example shown, this spring element is formed by two wire spring washers 7 and two spacer rings 8. This can increase the holding force in the locked state and thus prevent or impede unintentional release of the connection.
[0046] The construction of the helical groove 5 can be seen more clearly from the detailed representation of the developed casing of the sleeve 3 of an embodiment of a current socket 1 designed according to the invention according to Fig. 4A and three different views of the sleeve 3 according to Figs. 4B to 4D. Accordingly, the helical groove 5 in the sleeve 3 has at least two regions a, c with a positive pitch, wherein at the end of the regions a, c with a positive pitch there are regions b, d with a negative pitch to form a respective locking step as well as regions e with or without a significant pitch. Accordingly, two locking steps are realized with the sleeve 3 shown.By providing the helical groove 5 in the sleeve 3 of the power socket 1 with at least two areas a, c with a positive gradient and arranging areas b, d with a negative gradient at the end of each area a, c with a positive gradient, the operator can be given haptic feedback when the respective locking step is reached. For defined locking, there can be areas e with or without a significant gradient between the areas a, c with a positive gradient and the areas b, d with a negative gradient. However, these areas e with or without a significant gradient are not absolutely necessary. Furthermore, it is possible for the areas a, c with a positive gradient and the areas b, d with a negative gradient to be designed in a graded manner, i.e. their gradient is not necessarily constant but can, for example, be rising or falling.
[0047] Fig. 5 shows a sectional view through a power socket 1 designed according to the invention according to Fig. 3 in the assembled state. Accordingly, the two parts 11, 12 of the receptacle 3' of the base body 2 of the power socket 1 are connected to one another, for example, pressed together. The sleeve 3 is arranged inside the receptacle 3' of the base body 2 and is mounted displaceably in the axial direction X relative to the receptacle 3' by a spring element 6 in the form of two wire spring washers 7 and two spacer rings 8. As a result, an increased force can be exerted on the end face 14 of the receptacle 3' when the power socket 1 is connected to the power plug 30. A coating 15, for example made of silver, can be arranged on the end face 14 of the receptacle 3' of the base body 2, which coating reduces the contact resistance R o further reduced and also protects against corrosion.
[0048] Fig. 6 shows a sectional view through a power coupling 50 with the power plug 30 not yet engaged in the power socket 1. Accordingly, the two wire spring washers 7 of the spring element 6 are relaxed. A through-bore 17 for conducting a protective gas or the like is arranged in the power plug 30 in the receptacle 3' of the base body 2, which continues in the power socket 1 in the axial direction X.
[0049] In Fig. 7, the sectional view through the power coupling 50 according to Fig. 6 is shown with the power plug 30 engaged in the power socket 1. In this case, the wire spring washers 7 of the spring element 6 are compressed and the spring force is transferred accordingly to the end face 14 of the receptacle 3' of the base body 2 of the power socket 1. As a result, the contact resistance R o the connection of the power coupling 50 can be reduced.
[0050] Fig. 8 shows a force-displacement preload diagram of a power coupling 50 with a power socket 1 designed according to the invention with two locking steps (curve C) compared to a power coupling 50 with a conventional power socket 1 (curves A and B). The force F in N is plotted against the distance s in mm. In a conventional plug connection, for example a common DINSE® connector (curve A), the force F is very steep as a function of the distance s. The curves for closing the plug connection and for opening the plug connection are essentially the same. In a further development of the plug with a spring-loaded locking lug (curve B), the force F is flatter as a function of the distance s. The curve of the force F for releasing the connection is below the curve of the force F for closing the plug connection. Accordingly, the loosening torque is lower than the tightening torque.In the case of the power coupling 50 with a power socket 1 according to the invention (curve C), a force-displacement curve results which, due to the above-described course of the helical groove 5 in the sleeve 3 with two areas with a negative gradient, has two locking stages. In the locked state of the plug connection, a lower force F results in each case. Accordingly, a certain force F must be overcome to open the connection or to detach the power plug 30 from the power socket 1 according to the invention. This leads to a better hold of the plug connection, whereby the risk of unintentional detachment of the plug connection can be significantly reduced.
[0051] Finally, Fig. 9 shows an example of the contact resistance R o and the power loss P va power coupling 50 with a power socket 1 designed according to the invention (bar diagrams I) compared to power couplings 50 with conventional plug connections (bar diagrams II to IV). The bar diagrams according to I show the contact resistance R o and the power loss P v a current coupling 50 with the current socket 30 according to the invention. Both the contact resistance Ru and the power loss P v have low values . The bar diagrams according to II show the contact resistance Ru and the power loss P v with a fixed, optimal connection of a conventional DINSE® connector. The values for the contact resistance R o and the power loss P vare comparable to those of the inventive power socket 1 according to I and are, for example, a few tens of pOhm or a few watts. With a loose DINSE® connector (bar diagrams according to III), the contact resistance Ru and the power loss P increase. v increases significantly, for example to over 100 pOhm or several tens of watts. The bar diagrams according to IV show the case of a loose DINSE® connector, which is also oxidized. Accordingly, the contact resistance R o and the power loss P v increases significantly, for example to several hundred pOhm or approximately 100 W. Such values can lead to the destruction of the power coupling 50 due to local overheating. The power socket 1 according to the invention, on the other hand, ensures an optimal, stable and permanent connection with minimal contact resistance Ru and minimal power loss P v, whereby the risk of destruction of the components of the power coupling 50, the power cables 40 and connected devices and the risk of injury to the user can be reduced as far as possible.
Claims
Patent claims:
1. Power socket (1) for detachable connection to a power plug (30), comprising a base body (2) made of electrically conductive material with a bore (2') for receiving a substantially cylindrical bolt (31) of the power plug (30) and with a device (4) for connection to a power cable (40), wherein a helical groove (5) for receiving a locking lug (32) of the power plug (30) is arranged in the base body (2), wherein the base body (2) has a sleeve (3) with the helical groove (5) and a receptacle (3') for the sleeve (3), characterized in that the helical groove (5) has at least two regions (a, c) with a positive pitch, and at the end of each region (a, c) with a positive pitch, regions (b, d) with a negative pitch are arranged to form a respective locking step,wherein the receptacle (3') is made of metal or a metal alloy with a casing (13) of electrically insulating material and the sleeve (3) is made of harder material than the receptacle (3').
2. Power socket (1) according to claim 1, characterized in that a spring element (6) for resiliently mounting the sleeve (3) in the axial direction (X) of the receptacle (3') is arranged in the receptacle (3') for the sleeve (3) of the base body (2).
3. Power socket (1) according to claim 2, characterized in that the spring element (6) is formed by at least one wire spring washer (7).
4. Power socket (1) according to claim 3, characterized in that the spring element (6) is formed by two wire spring washers (7) and a spacer ring (8) arranged between the wire spring washers (7).
5. Power socket (1) according to one of claims 1 to 4, characterized in that the sleeve (3) has positioning elements (9), in particular axial locking lugs (10), to prevent rotation relative to the receptacle (3') of the base body (2).
6. Power socket (1) according to one of claims 1 to 5, characterized in that the receptacle (3') of the base body (2) consists of two parts (11, 12) which can be connected to one another, wherein the two parts (11, 12) of the receptacle (3') of the base body (2) can preferably be connected to one another via a press fit.
7. Power socket (1) according to one of claims 1 to 6, characterized in that the receptacle (3') is formed from steel or a steel alloy, preferably from brass or a brass alloy, and that the sleeve (3) is formed from steel or a steel alloy.
8. Power socket (1) according to one of claims 1 to 7, characterized in that the receptacle (3') of the base body (2) has a flat end face (14) for contacting.
9. Power socket (1) according to claim 8, characterized in that the end face (14) of the receptacle (3') has a coating (15), for example a silver coating.
10. Power socket (1) according to one of claims 1 to 9, characterized in that the groove (5) in the sleeve (3) extends over a rotation angle (a) of 90° to 270°.
11. Power socket (1) according to one of claims 1 to 10, characterized in that the pitch of the regions (a, c) of the groove (5) with positive pitch is between 1 mm and 8 mm per 360°.
12. Power socket (1) according to one of claims 1 to 11, characterized in that the pitch of the regions (b, d) of the groove (5) with negative pitch for forming the locking steps is between 0.1 mm and 20 mm, preferably between 1 mm and 20 mm, particularly preferably between 5 mm and 20 mm per 360°.
13. Power socket (1) according to one of claims 1 to 12, characterized in that the helical groove (5) has regions (e) without a slope after the regions (b, d) with a negative slope.
14. Power socket (1) according to one of claims 1 to 13, characterized in that the device (4) for connection to a power cable (40) is formed by a screw connection (16).
15. Power socket (1) according to one of claims 1 to 14, characterized in that the receptacle (3') of the base body (2) has a through bore (17) or the like in the axial direction (X) for guiding a protective gas (S) or the like.
16. Power coupling (50) consisting of a power socket (1) and an associated power plug (30) with a substantially cylindrical bolt (31), characterized in that the power socket (1) is designed according to one of claims 1 to 15.
17. Power coupling (50) according to claim 16, characterized in that the sleeve (3) of the power socket (1) is made of harder material than the cylindrical bolt (31) of the power plug (30).