Short circuit detection device and corresponding vehicle
Patent Information
- Application Number
- ES2023195195T
- Authority / Receiving Office
- ES · ES
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-09-04
- Publication Date
- 2026-09-14
- Estimated Expiration
- 2043-09-04
Smart Images
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Abstract
Description
Short circuit detection device and corresponding vehicle The present invention relates to a short-circuit detection device, comprising a power supply terminal, a fed terminal, and a connecting element between the power supply terminal and the fed terminal, the power supply terminal, the fed terminal and the connecting element forming an electrical connection section, which is devoid of electrical insulation, the power supply terminal and the fed terminal each comprising an insulated section provided with electrical insulation, and the short-circuit detection device comprising an element for detecting an electric arc emanating from the electrical connection section. The motor's electrical connection to its power supply is known through a terminal box. This allows for easy coupling and uncoupling of the motor from its power supply, while also ensuring the detection of uninsulated electrical connections within the terminal box, in a closed enclosure accessible only by opening the terminal box cover. Within the terminal box, malfunctions can occur, introducing short circuits and electrical arcs that can lead to the destruction of the terminal box or even the windings. Short circuits generally occur between two phases. In some cases, such as with an asynchronous motor, interrupting the power supply will stop the short circuit. In motors using permanent magnets, interrupting the power supply does not always stop a short circuit. In fact, if the power disconnection point is upstream of the short circuit, the short circuit will continue to propagate if the motor continues to rotate under load, as in the case of a railway vehicle with multiple traction motors. A detection device is known from patent application FR2737615A1. Other devices are known from documents US6512444B1, DE2644422A1, US2021143629A1, DE102015016696A1 and US4067052A. Document EP3595123 describes a power distribution system. Document DE19631088 describes a protective device for an electrical installation. Document US2019 / 319451 describes a window heating control system. The invention aims to propose a short-circuit detection device that is simple, inexpensive, and reliable. To that effect, the invention relates to a detection device as indicated above, characterized in that the detection element comprises an electrically conductive element, having a detection section, and a detection coating that is electrically insulating and thermally degradable and surrounds the detection section, and in that the detection section extends to a detection distance from the electrical connection section. Depending on the specific embodiment of the detection device, it may include one or more of the following features: the detection distance is less than the range of an electric arc emanating from the electrical connection section and sufficient to thermally degrade the detection coating, and / or The detection distance is such that, on the one hand, the breakdown voltage between the detection section and the electrical connection section in the presence of the detection coating is greater than the nominal voltage of the supply terminal, and on the other hand, the breakdown voltage between the detection section and the electrical connection section, in the absence of the detection coating, is less than the nominal voltage of the supply terminal, and / or the detection distance is less than the distance between the electrical connection section and a supplementary electrical circuit element, which is the electrical circuit element closest to this electrical connection section; The detection coating is a coating suitable for degradation under the effect of heat generated by an electric arc, preferably in which the detection coating comprises or is made of heat-sensitive polymers, such as PVC, fluoropolymer or polypropylene, chemically doped leading to a decrease in electrical resistance in the event of an increase in temperature; The electrically conductive element is connected to the electrical ground or the electrical mass; The short-circuit detection device comprises a short-circuit detection module, which is adapted to detect an electrical grounding of the supply terminal and the terminal supplied by means of the electrically conductive element; the electrically conductive element of the detection element has a circular, elliptical, square or rectangular cross-section and / or in which the electrically conductive element is in the form of a wire, rod or flat cable; the detection element consists of a single branch or forms a loop of two branches; The short-circuit detection device comprises a terminal box, The power supply terminal is located inside the terminal box. The powered terminal is located inside the terminal box. the connecting element is arranged inside the terminal box and the detection section is arranged inside the terminal box; The detection device comprises a supplementary power supply terminal arranged within the terminal box, a supplementary powered terminal arranged within the terminal box, and a supplementary connecting element connecting the supplementary power supply terminal and the supplementary powered terminal, which is arranged within the terminal box. The supplementary power terminal, the supplementary powered terminal, and the supplementary connecting element define a supplementary electrical connection section, devoid of electrical insulation, and the detection distance is less than the distance between the electrical connection section and the supplementary electrical connection section, and Preferably, in which the terminal box comprises a separating wall between the electrical connection section and the supplementary electrical connection section. The invention also relates to a vehicle comprising an electric motor having at least two phases and a short-circuit detection device connected to the electric motor, characterized in that the short-circuit detection device is a device such as defined above. The invention will be better understood by reading the following description, given only by way of example and made with reference to the accompanying drawings, in which: [Fig 1] Figure 1 schematically shows a vehicle comprising a detection device according to the invention; [Fig.2] Figure 2 shows a cross-section of the detection device along line II-II of Figure 1; and [Fig 3] Figure 3 shows a variant of a detection device from Figures 1 and 2, with the view in Figure 3 corresponding to the view in Figure 2. In what follows, expressions such as "connected", "related" or "isolated" refer, unless otherwise indicated, to electrical characteristics and not to mechanical characteristics. Figure 1 shows a vehicle designated with the general reference 2. Vehicle 2 is in the present case a railway vehicle such as a locomotive and is represented very schematically. Vehicle 2 comprises a chassis 4, connected to ground or electrical mass, and at least one electric motor 6, which may be a synchronous or asynchronous motor. The electric motor 6 comprises two or three phases, of which one phase P1 is shown in more detail and a supplementary phase P2 is shown very schematically (see below). The electric motor 6 is adapted to drive the vehicle's drive wheels. Vehicle 2 comprises an electrical voltage source 8, which may be a direct or alternating current voltage source and is adapted to supply electricity to the electric motor 6. For this purpose, the electric motor 6 is connected to the electrical voltage source 8 by an electrical connection circuit 9. The electrical connection circuit 9 comprises a short-circuit detection device 10. The short-circuit detection device 10 comprises a power supply terminal 12, connected to the electrical voltage source 8, a powered terminal 14, connected to the electric motor 6, in the present case to the winding of a stator 16 of the electric motor. The short-circuit detection device 10 comprises a connecting element 18 between the supply terminal and the powered terminal. This connecting element 18 mechanically and electrically joins the supply terminal and the powered terminal and is, for example, a screw, bolt, or other mechanical fastener. The supply terminal 12 in this case comprises one end of a cable 20, and the powered terminal 14 comprises a winding connection connector 22. The power supply terminal 12, the powered terminal 14 and the connecting element 18 form an electrical connection section 24 which is devoid of electrical insulation and therefore bare. The power supply terminal 12 comprises an insulated section 26 provided with electrical insulation and the power supply terminal 14 comprises an insulated section 28 provided with electrical insulation. The short-circuit detection device 10 comprises a terminal box 30. The terminal box 30 is provided in this case with a terminal box support 32 and a terminal box cover 34. The supply terminal 12 is arranged inside the terminal box, the powered terminal 14 is arranged inside the terminal box, and the connecting element 18 is arranged inside the terminal box. The insulated sections 26 and 28 are extended, and the extension passes through the terminal box support 32. The short-circuit detection device 10 further comprises a detection element 36 for an electric arc emanating from the electrical connection section 24. This detection element 36 comprises an electrically conductive element 38 having a detection section 40. The electrically conductive element 38 is connected to the electrical ground or earth, in this case to chassis 4. The electrically conductive element 38 is, for example, copper, aluminum, or steel. The sensing element 36 comprises a sensing coating 42 that is electrically insulating and thermally degradable (Figure 2). The sensing coating 42 surrounds the sensing section 40, in particular along its entire length and / or the entire length of the sensing section. In this case, the sensing coating surrounds the electrically conductive element along its entire length within the terminal box, in a section that passes through a wall of the terminal box 30, and a portion of its length that extends from the terminal box 30. Only a section of the sensing element 36 that extends outside the terminal box 30 lacks a sensing coating 42. The sensing coating 42 is a coating designed to degrade under the heat generated by an electric arc. The sensing coating may comprise or be made of heat-sensitive polymers, such as PVC, fluoropolymer, or polypropylene, chemically doped to decrease electrical resistance with increasing temperature. The thermal degradation temperature, i.e., the temperature at which the thermal coating degrades, may range from 80 °C to 240 °C, and specifically from 100 °C to 200 °C. The electrically conductive element 38 of the sensing element may have a circular, elliptical, square, or rectangular cross-section. The electrically conductive element may be in the form of a wire, rod, or flat cable. In the case of the embodiment shown in Figures 1 and 2, the detection element 36 consists of a single branch extending inside the terminal box 30. The detection section 40 extends, in particular along its entire length and / or its entire extent, to a detection distance DD from the electrical connection section 24. The detection distance DD is chosen such that, during the occurrence of an electric arc at the level of the electrical connection section 24, this electric arc thermally degrades the detection coating 42 and establishes an electrical arc connection between the connection section and the electrically conductive element 38. This connection to the electrical mass or ground is then detected, for example, by a short-circuit detection module 50 that is part of the detection device. This detection module 50 is, for example, a module suitable for detecting a current difference between two phases, for example, P1 and P2 of the electric motor supply circuit 6, or for detecting a leakage current between the phase and the electrical mass or ground (which generally comprises the vehicle chassis 4) (Figure 1).Depending on the detection of a short circuit by the detection module 50, the detection module can emit a detection signal or cut off the power supply to the electric motor 6. The short-circuit detection module 50 can comprise, for example, a differential switch or a differential circuit breaker. The detection distance DD can be determined, for example, as follows: a) the detection distance is less than the range of an electric arc emanating from the electrical connection section 24 and sufficient to thermally degrade the detection coating 42; and / or b) the detection distance DD is such that, on the one hand, the breakdown voltage between the detection section 40 and the electrical connection section 24 in the presence of the detection coating is greater than the nominal voltage of the supply terminal, and on the other hand, the breakdown voltage between the detection section and the electrical connection section in the absence of the detection coating is less than the nominal voltage of the supply terminal; and / or c) the detection distance DD is less than a distance between the electrical connection section 24 and a supplementary electrical circuit element, which is the electrical circuit element closest to that electrical connection section. For case c), the supplementary electrical circuit element is, for example, a supplementary connection section from another phase of the same electric motor 6 (see below). For nominal electrical voltages between 1 kV and 5 kV, the detection distance is, for example, between 1 mm and 5 mm. In general, the detection distance can therefore be between 1.0 mm and 5.0 mm. In this case, the detection section 40 is arranged inside the terminal box 30. As shown in Figure 2, the short-circuit detection device 10 may comprise an additional power supply terminal 112, which may be arranged inside the terminal box, an additional powered terminal 114, which may also be arranged inside the terminal box, and an additional connecting element 118. The connecting element 118 joins the additional power supply terminal and the additional powered terminal and may likewise be arranged inside the terminal box. These additional elements—the additional power supply terminal 112, the additional powered terminal 114, and the additional connecting element 118—may be identical to the elements described above 12, 14, and 18. These additional elements form part, for example, of an additional phase P2 for supplying electricity to the electric motor 6. The electric motor 6 comprises, for this purpose, an additional stator winding 116. The supplementary power terminal 112, the supplementary powered terminal 114 and the supplementary connecting element 118 define a supplementary electrical connection section 124 without electrical insulation. The detection distance DD is less than the section distance DT between the electrical connection section 24 and the supplementary electrical connection section 124. The terminal box 30 in this case comprises a separation wall 130 between the electrical connection section and the supplementary electrical connection section. The embodiment of Figure 3 differs from the embodiment described above only in the following respects. Analogous elements bear the same references. In the embodiment shown in Figure 3, the detection element 36 forms a two-branch loop. The detection device according to the present invention allows for the simple and inexpensive detection of an electric arc. The detection device is also suitable for retrofitting existing electrical circuits. The preceding description contains technical features of the invention. These technical features, although presented in a technical context and possibly in combination with other technical features, may be used individually each time, without the other technical features, provided this is technically feasible.
Claims
1. A short-circuit detection device comprising a power supply terminal (12), a powered terminal (14), and a connecting element (18) between the power supply terminal and the powered terminal, the power supply terminal, the powered terminal, and the connecting element forming an electrical connection section (24) that is devoid of electrical insulation, the power supply terminal and the powered terminal each comprising an insulated section (26, 28) provided with electrical insulation, the short-circuit detection device comprising an arc detection element (36) emanating from the electrical connection section, characterized in that the detection element comprises an electrically conductive element (38) having a detection section (40), and a detection coating (42) that is electrically insulating and thermally degradable and surrounds the detection section,and because the detection section (40) extends to a detection distance (DD) from the electrical connection section.
2. Short-circuit detection device according to claim 1, wherein the detection distance (DD) is less than the reach distance of an electric arc emanating from the electrical connection section (24) and suitable for thermally degrading the detection coating (42), and / or the detection distance (DD) is such that, on the one hand, the breakdown voltage between the detection section (40) and the electrical connection section (24) in the presence of the detection coating (42) is greater than a nominal voltage of the supply terminal, and on the other hand, the breakdown voltage between the detection section and the electrical connection section, in the absence of the detection coating, is less than the nominal voltage of the supply terminal.and / or the detection distance (DD) is less than a distance (DT) between the electrical connection section (24) and a supplementary electrical circuit element, which is the electrical circuit element closest to this electrical connection section.
3. Short-circuit detection device according to claim 1 or 2, wherein the detection coating (42) is a coating suitable for degradation under the effect of heat generated by an electric arc, preferably wherein the detection coating (42) comprises or is made of heat-sensitive polymers, such as PVC, fluoropolymer, or polypropylene, chemically doped leading to a decrease in electrical resistance in the event of an increase in temperature.
4. Short-circuit detection device according to any one of the preceding claims,in which the electrically conductive element (38) is connected to the electrical earth or ground.
5. Short-circuit detection device according to any one of the preceding claims, wherein the short-circuit detection device comprises a short-circuit detection module (50) suitable for detecting a grounding of the supply terminal and the terminal supplied by means of the electrically conductive element (38).
6. Short-circuit detection device according to any one of the preceding claims, wherein the electrically conductive element (38) of the detection element has a circular, elliptical, square, or rectangular cross-section and / or wherein the electrically conductive element is in the form of a wire, rod, or flat cable.
7. Short-circuit detection device according to any one of the preceding claims,wherein the detection element consists of a single branch or forms a loop of two branches.
8. Short-circuit detection device according to any one of the preceding claims, wherein the short-circuit detection device comprises a terminal box (30), the supply terminal (12) is arranged within the terminal box, the powered terminal (14) is arranged within the terminal box, the connecting element (18) is arranged within the terminal box, and the detection section (40) is arranged within the terminal box.
9. Short-circuit detection device according to claim 8, wherein the detection device comprises an additional supply terminal (112) arranged within the terminal box, an additional powered terminal (114) arranged within the terminal box,A supplementary connecting element (118) joining the supplementary supply terminal and the supplementary powered terminal and arranged within the terminal box (30), the supplementary supply terminal, the supplementary powered terminal, and the supplementary connecting element defining a supplementary electrical connection section (124), devoid of electrical insulation, and in which the detection distance is less than the distance (DT) between the electrical connection section and the supplementary electrical connection section, and preferably in which the terminal box comprises a separating wall (130) between the electrical connection section and the supplementary electrical connection section.
10. Vehicle (2), in particular a railway vehicle, of the type comprising an electric motor (6) having at least two phases (P1; P2) and a short-circuit detection device (10) connected to the electric motor,characterized in that the short-circuit detection device is a device according to any one of the preceding claims.