Apparatus having isolation for overvoltage discharge device

Abstract

The invention relates to a device having an isolating device (1) for an overvoltage discharge arrangement (2). A first contact means (8) and a second contact means (9) of the isolating device (1) are connected via a first path (16) having a thermally triggerable switching element (12). A second path (17) is arranged electrically in parallel to the first path (16). An impedance element (10) is arranged in the second path (17), wherein a spark gap (11) is arranged in the first path (16).

Description

Technical Field

[0001] The present invention relates to an apparatus having an isolation device for an overvoltage discharge device, the isolation device having a first contact device and a second contact device, a first path arranged between the first contact device and the second contact device, the first path having a thermally triggerable switching element. Background Technology

[0002] For example, such a device is known from international publication WO 2018 / 188 897. Therein is described a separation device and switching device having a so-called thermal separation point. The thermal separation point is equipped with a movable conductor element that ensures defined circuit function even under gradual heating. For this purpose, it is specified that the movable conductor element at this location can move between three positions when using brushes or sliding contacts.

[0003] Using three positions may have a positive impact on the operational characteristics of known devices. However, this structure should be considered costly and large in size. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to provide a low-cost device that has sufficiently reliable operating characteristics in a compact size.

[0005] According to the present invention, in the type of device mentioned at the beginning, this technical problem is solved by arranging a second path having an impedance element in electrical parallel with the first path between the first contact device and the second contact device, wherein a spark gap (e.g., a level spark gap) is arranged in the first path.

[0006] Isolation devices are used to disconnect conductive connections. Such connections can be, for example, grounding connections. This grounding is used to temporarily induce ground faults and thereby reduce overvoltages in the power transmission network. To ensure that a grounding connection is only established when an overvoltage exceeds a limit, so-called overvoltage discharge devices are used. Overvoltage discharge devices are used in grounding connection devices that extend from a phase conductor of the power transmission network to the ground potential. Overvoltage discharge devices, for example, have varistors that change their impedance characteristics according to the applied voltage. Depending on the voltage level, the varistor exhibits different threshold values; above this threshold, the varistor exhibits low resistance characteristics, and below this threshold, the varistor exhibits high resistance characteristics.

[0007] To prevent the permanent maintenance of the ground connection in fault conditions, such as a short circuit in a varistor, an isolation device is used that disconnects the ground connection in such fault conditions. This is typically irreversible if the isolation device is compromised.

[0008] Isolation devices typically have a first contact and a second contact. The contacts connect the isolation device to a lead-out connection. Thus, for example, one contact can be electrically connected to an overvoltage discharge device, while the other is connected to ground potential. A thermally triggerable switching element must be provided so that the isolation device can respond in fault conditions. Triggering of the switching element is performed based on thermal load. That is, when a certain energy input (e.g., heat) is exceeded, the thermally triggerable switching element disconnects (interrupts). For this purpose, the thermally triggerable switching element is arranged in a first path that extends between the first and second contacts. The thermally triggerable switching element can, for example, be constructed as a fuse.

[0009] Advantageously, the second path is arranged electrically in parallel with the first path, and like the first path, the second path extends between the first contact device and the second contact device. Advantageously, an impedance element is arranged inside the second path. Advantageously, the impedance element is an ohmic resistor with high resistance (e.g., several thousand ohms, tens of thousands of ohms) (or alternatively, a varistor or an ohmic resistor with a parallel capacitor). The impedance element allows the leakage current flowing through the varistor to flow to ground potential to a limited extent, for example, via an isolation device. The leakage current is essentially limited by the impedance of the varistor in the resistive state.

[0010] By arranging a spark gap (e.g., a level spark gap) preferably in series with the thermally triggerable switching element located therein in the first path, this leakage current, representing a normal operating variable, can potentially flow away only through the impedance element. The first path remains free from this current load. Correspondingly, the thermally triggerable switching element is also free from preload, thereby preventing aging or undesirable preheating on the same thermally triggerable switching element.

[0011] For example, due to aging of the upstream overvoltage discharge device or short circuit in the varistor, the voltage drop across the impedance element increases with the increase of leakage current. When the leakage current increases and exceeds an intolerable threshold, it can be called interference current. When interference current occurs, the voltage drop across the impedance element reaches a limit value. This is called reaching the limit voltage. Exceeding the limit voltage causes an arc to form in the spark gap, thereby allowing current to flow through the first path. Corresponding to the impedance ratio set in the first and second paths, interference current is correspondingly divided in the first and second paths. The interference current is diverted from the second path to the first path. The spark gap is closed. Due to the closure of the spark gap, the thermally triggered switching element still located in the first path is subjected to the current (and corresponding current heat) that appears in the first path, and the switching element is exposed to the heat energy of the arc. Due to the current flow in the first path and / or the thermal effect of the arc in the spark gap, heat energy is introduced into the isolation device, causing the thermally triggered switching device to switch. The thermally triggered switching element is activated (triggered) via the spark gap. The spark gap and the thermally triggerable switching element are connected in series in the first path. With the triggering of the switching element, the spark gap is preferably extended. In other words, at least one arc root (arc angle) of the spark gap (particularly due to burn-out) shifts its position.

[0012] Advantageously, it can be further specified here that the heat-triggerable switching element has a first switching section and a second switching section, the first switching section and the second switching section being electrically connected to each other via a predetermined heat-triggerable break point.

[0013] A thermally triggered switching element is used to switch based on changes in the applied thermal energy. Preferably, the thermally triggered switching element can cause disconnection or isolation when the thermal energy rises. Disconnection or isolation is characterized by the impedance present in the switching element preferably increasing towards infinity. By using a switching element having a first switching section and a second switching section, the switching sections can be moved relative to each other to change the impedance characteristics of the thermally triggered switching element. For this purpose, it is advantageous to arrange a predetermined thermally triggered break point between the first and second switching sections. Advantageously, the predetermined break point has a lower heat carrying capacity than at least one of the switching sections. Here, the predetermined break point can be implemented in different ways. For example, the first and second switching sections can be constructed discretely and connected to each other with the predetermined break point constructed. The predetermined break point can be, for example, a conductive connection device between the first and second switching sections. The first and second switching sections can be connected to each other, for example, by material bonding. Therefore, the two switching sections can be welded or brazed to each other, for example. However, other bonding processes can also be used between the first and second switching sections. For example, the first and second switch segments can be connected to each other by frictional fit, form fit, etc. However, such a heat-triggered predetermined break point can also be constructed, for example, by a material weakening portion relative to the switch segment (particularly due to a reduced cross-section).

[0014] In a preferred variation, the first and second switching sections are connected by means of conductive solder material. Preferably, when the solder is placed in the middle, it is advantageous for the switching sections to overlap planarly. In particular, the predetermined thermally triggerable break point can be arranged near the spark gap. Particularly advantageously, it can be specified that the arc root of the spark gap is at least temporarily arranged near the predetermined thermally triggerable break point. This has the advantage that the heat energy generated by the arc in the spark gap can act more directly on the predetermined thermally triggerable break point.

[0015] Advantageously, it can also be specified that a spring element is used to apply a preload force that presses the second switch section against the second contact device.

[0016] A preload can be used to place a predetermined thermally triggerable break point under mechanical stress and, for example, fix the position of this predetermined thermally triggerable break point. Therefore, the operation of the thermally triggerable switching element is guaranteed due to the fixed position. For example, the preload of a spring element can also ensure electrical contact, such as with a sliding contact device. Furthermore, it is possible for the preload of the spring element to drive relative movement of the switch sections of the thermally triggerable switching element that can move relative to each other. Thus, the spring element is a driving device for relative movement of the switch sections of the thermally triggerable switching element.

[0017] Between the second contact device and the second switching section, the preload of the spring element can be used to ensure electrical (sliding) contact between the second switching section and the second contact device. The contact between the second switching section and the second contact device can preferably be located in the region where the second contact device at least temporarily provides an arc root for the spark gap. When the spring element is used as a drive element for relative movement of the switching sections, the spring element can preferably induce a substantially linear relative mobility or movement between the two switching sections. This enables the realization of isolation devices with narrow or compact constructions.

[0018] Furthermore, it can be advantageously specified that the preload force acts substantially parallel to the axis extending from the first contact device to the second contact device on at least one switching section.

[0019] The preload can be applied to at least one switching section in such a way that, after the thermally triggered switching element is actuated, it moves linearly relative to another switching section. Preferably, the shaft extends through the contact surfaces of the first and second contact devices, which are used for electrical contact with the grounding connection device. The preload can also be transmitted via a predetermined break point of the thermally triggered switching element. Preferably, the tension can extend between the switching section and the second contact device. The second contact device can serve as a position-fixed support to absorb the force exerted by the spring element. Conversely, the actuated switching section can transmit force via the predetermined break point of the thermally triggered switching element, such that even when the thermally triggered switching element is not actuated, force still flows through the predetermined break point. Thus, fixation, particularly of the first switching section, can also be achieved via the predetermined break point (when the preload of the spring element mainly acts on the second switching section). For example, the first switching section can be supported on a protrusion in a spring-loaded manner.

[0020] Advantageously, it can be further specified that the first switching section is pressed against the first contact device by a spring element when the insulating section is sandwiched in the middle.

[0021] The first contact device has conductive properties to perform the contact function. Similarly, the second contact device is also designed to have conductive properties so that it can also perform the contact function there. Supporting the first switch section with an intermediate insulating section allows the first switch section to be supported and fixed to the first contact device in an electrically insulating manner. Therefore, for example, it is possible to tighten the interlocking shoulders of the first switch section or the first contact device, wherein an insulating section is sandwiched in the middle of the clamping area. This makes it possible to, in particular, at least one section that temporarily forms a spark gap between the first switch section and the first contact device, and to arrange the first switch section in an electrically insulating manner from the first contact device.

[0022] Furthermore, it can be advantageously specified that the device has a housing with a first housing section and a second housing section, in which a first contact device, a second contact device and a switching element are embedded, wherein the engagement axis between the first housing section and the second housing section is oriented substantially transversely to the axis extending from the first contact device to the second contact device.

[0023] The housing protects the isolation device from external influences. Here, the housing can be used to position the various components of the isolation device relative to each other. Therefore, a receiving portion can be provided within the housing for complementary positioning of components such as a first contact device, a second contact device, a thermally triggered switching element, an impedance device, a spark gap, etc. The housing can serve as the chassis of the isolation device. Furthermore, the housing can be designed to guide relative movement when the thermally triggered switching element is actuated, or to allow deformation, forced guidance, or separation of at least a portion of the switching element within the housing. This allows for the defined actuation of the thermally triggered switching element.

[0024] By using two housing segments, the assembly of the housing can be simplified, and components such as contact devices, switching elements, and impedance elements can be positioned. The housing segments can, for example, be designed as essentially half-shells. The housing can define an internal space within which the various components of the isolation device can be arranged. However, the housing segments can have corresponding receiving portions (e.g., recesses, shoulders, protrusions, etc.) into which the components of the isolation device can be inserted.

[0025] Preferably, the engagement axis is oriented between the housing segments such that it is substantially transverse to the axis extending from the first contact device to the second contact device. Therefore, it is possible to provide housings or supports for components movable relative to each other within the housing or on the housing segments, such that the engagement points between the housing segments should be kept as free from overload as possible when they are under load. For example, it can be specified that thermally triggerable switching elements have movable switching segments that separate from each other upon triggering. Preferably, this movement can be a linear relative movement between the switching segments. Preferably, the axis of this linear movement is oriented substantially transverse to the engagement axis between the first and second housing segments. This enables, for example, the provision of guide rails that do not extend at the engagement points between the housing segments. Advantageously, the relative movement between the switching segments is oriented substantially parallel to the axis between the first and second contact devices.

[0026] Another advantageous design could specify that the housing is surrounded by a cover that fixes the first housing section and the second housing section relative to each other.

[0027] The housing can be enclosed by a cover. The cover, for example, can fix the first housing segment relative to the second housing segment. The housing segments can, for example, be assembled to form a cylindrical circumferential surface, which is surrounded by the cover. The joining axis between the first and second housing segments can preferably be a cylindrical axis transverse to the cylindrical circumferential surface. Therefore, by using the cover for enclosure, radial separation of the housing segments is prevented. Preferably, the housing segments can each be designed as a half-shell, which is assembled to have a substantially cylindrical circumferential surface and is surrounded by the cover. The cover, for example, can be designed as a sleeve that completely surrounds the housing at least partially on its circumferential side. Therefore, a joining gap is formed between the housing and the cover.

[0028] Another advantageous design could specify that the cover surrounds the housing in a sleeve manner, wherein the first sleeve section and the second sleeve section are joined together by an insertion method.

[0029] By designing the cover as a sleeve, the joints between the shell sections can be covered. This prevents particles from penetrating the joints. Advantageously, the sleeve can completely surround the shell on its circumference and can also seal the shell on its end face. On the end face side, the corresponding conductive penetrator (German: The sleeve can be positioned within the housing to enable electrical contact through the housing. Advantageously, the housing may be configured to have a first sleeve section and a second sleeve section, which can be joined together by a plug-in connection. Preferably, the plug-in connector may be designed as annular, resulting in a circumferential engagement gap within the housing. The engagement gap between the sleeve sections may be sealed, for example, by means of a sealing element. Furthermore, the sleeve sections may be form-fitted together and / or thereby fixed in the axial and radial directions. In addition to fixing the relative positions of the sleeve sections, a clamping, for example, through-hole element may be specified to enable electrical contact with a contact device of the isolation device located within the housing. For example, one of the contact devices may be designed to be elastically resilient, such that the sleeve section applies a clamping force to the through-hole element and ensures electrical contact.

[0030] The sleeve sections can be connected to each other in a torsion-resistant manner. For this purpose, corresponding locking lugs can induce torsion locking. Furthermore, additional tenon and groove structures can be provided between the sleeve sections.

[0031] Another advantageous design could specify that the internal space defined by the housing is connected to the joint gap located between the housing and the cover via at least one channel.

[0032] The housing surrounds an internal space, which may house, for example, impedance elements, contact devices, spark gaps, and thermally triggered switching elements. Specifically, the spark gap can be positioned within the housing, i.e., within the internal space. When an electric arc occurs within the spark gap, it can cause gas expansion. These gases may be seeping into the housing or are burn-off products of components disposed within the housing. A channel, for example, penetrates the wall defining the internal space of the housing and connects the internal space to the surrounding environment. This surrounding environment of the housing may be a joint gap formed by a cover. Preferably, multiple channels may be distributed around the circumference of the housing, such that multiple channels lead to the joint gap between the housing and the cover. In the event of overpressure (e.g., by arc triggering), the overpressure can escape from the internal space into the joint gap via this channel. If the cover needs to be removed from the housing (e.g., by separating the sleeve sections from each other), this overpressure can be used to widen the joint gap. This allows for easier removal of the housing and the cover.

[0033] Furthermore, it can be advantageously specified that the first sleeve section has a conductive through-hole that is electrically connected to the first contact device, and the second sleeve section has a conductive through-hole that is electrically connected to the second contact device.

[0034] Using sleeve sections and conductive through-holes at the corresponding sleeve sections enables the transfer of potential through the sleeve sections to the interior, preferably to one of the contact devices of the isolation device. The sleeve sections and conductive through-holes can be connected to each other at a fixed angle. Preferably, the through-holes can be used to conductively contact the contact devices separately, such that they independently pass through the sleeve sections of the cover to contact the contact devices. When using covers with sleeve sections, elastically deformable elements, for example through the corresponding shaping of one of the contact devices, are preferably disposed inside the sleeve sections. The through-holes can be arranged at opposite ends of the cover or housing, preferably coaxially aligned with each other. In designs of substantially cylindrical housings or covers, the conductive through-holes should be positioned on opposite end faces. For example, considering bolts as through-holes, electrical contact can be achieved via the bolt through a nut / threaded hole.

[0035] Another advantageous design could be to specify that the first switching section has a greater wall thickness than the second switching section.

[0036] A thermally triggered switching element may have a first switching section and a second switching section. The two switching sections can be connected to each other via a predetermined break point, wherein relative movement between the two switching sections can occur during the triggering of the thermally triggered switching element. The use of switching sections with different wall thicknesses allows for adjustment of the operating characteristics of the thermally triggered switching element. The heat absorption or release of the first switching section can be altered by changing the wall thickness. Preferably, the first switching section can be designed as a fixed-position switching section. The second switching section can be designed as a movable switching section. The relative movement between the switching sections is preferably linear.

[0037] Furthermore, it can be preferably specified that the first switch section has a wider width than the second switch section.

[0038] The increased width of the first switch section relative to the second switch section allows the first switch section to be accommodated in one or more widened areas and to be locally fixed. In particular, when the first switch section is inserted into the housing (especially when the housing is assembled from multiple housing sections), the widened section of the switch section can be positioned close to the shoulder, making it more difficult to move the first switch section out of its fixed position.

[0039] Furthermore, it can be advantageously specified that the second switch section has a pleated area, particularly a pleated area in the form of a perforated area.

[0040] The second switch section is provided with a corrugated area, allowing it to deform during relative movement. This enables a space-saving structure for the isolation device. Thus, for example, the second switch section can be moved to the closed position by a spring device that has been pre-tensioned in a stationary state, and undergoes deformation there, such as folding or curling. This allows for the use of a compact housing structure.

[0041] Advantageously, it can also be specified that the second contact device has an arc root.

[0042] The second contact device may have an arc root (arc angle) to, for example, limit the spark gap. During the response of the thermally triggered switching device, the spark gap can be increased, for example, by the thermally triggered switching element changing its position due to relative movement, or by dissolving the thermally triggered switching element. In the untriggered state, the spark gap can be constructed, for example, between the arc root on the first contact device and the thermally triggered switching element (especially there on the first switching section). In the untriggered state of the switching device, the spark gap may have a size of several millimeters to keep any arc that might ignite near the area of ​​the thermally triggered switching element. After the thermally triggered switching element is triggered, the second contact device can provide the arc root. Thus, in the case of arc combustion, the spark gap between the first and second contact devices can be increased by a distance significantly greater than several millimeters (e.g., tens of millimeters). Preferably, the arc root of the second contact device can be used to contact one of the switching sections, particularly the second switching section, in a manner that allows for its slidable movement, so as to generate contact pressure between the second contact device and the second switching section. For this purpose, a spring device acting on the second switching section can be used. This spring device can, for example, deflect at an elbow. The elbow can be formed by a second contact device, particularly an arc root. There, a conductive sliding connection can be constructed when the second switching section is inserted.

[0043] Another advantageous design may specify that the first contact device is electrically connected to the overvoltage discharge device, particularly the first contact device being carried by the overvoltage discharge device, or that the second contact device is electrically connected to the overvoltage discharge device, particularly the second contact device being carried by the overvoltage discharge device.

[0044] Overvoltage discharge devices have an impedance element that changes according to voltage, called a varistor. As the voltage exceeds or falls below a threshold (limit, extreme value), the impedance characteristics of the varistor change. Below the threshold, its impedance tends to infinity. Above the threshold, the impedance of the varistor decreases towards zero. However, due to practical conditions, the impedance below the threshold does not appear infinite, but rather as a finite high resistance, resulting in leakage current.

[0045] Specifically, the first contact device can be electrically connected to the overvoltage discharge device using a through-hole. Therefore, the through-hole can be designed, for example, in the form of a bolt, which is inserted into a fitting of the overvoltage discharge device constructed in the opposite manner and fixed at an angle within the fitting. The isolation device can be fixedly connected to the overvoltage discharge device via a corresponding through-hole at an angle. The overvoltage discharge device can mechanically fix the isolation device using components provided for electrical contact. Furthermore, it can be specified that the second contact device is electrically connected to the overvoltage discharge device. The design and connection of the first contact device and the overvoltage discharge device also apply to the use of the second contact device for connection to the overvoltage discharge device.

[0046] Furthermore, it can be advantageously specified that the second contact device is subjected to a ground potential or the first contact device is subjected to a ground potential.

[0047] To connect an overvoltage discharge device to a grounding system, the overvoltage discharge device must be connected to the phase conductor to be protected. The phase conductor to be protected may conduct, for example, a high voltage. On the other hand, to apply a ground potential to the overvoltage discharge device, an intermediate connection device of the isolation device can be provided. For this purpose, a second contact device can be provided with a ground potential. For example, a bolt-type through-hole can be used, to which the ground wire is connected via a threaded connection. However, alternatively, it can be specified that the first contact device is applied a ground potential. Correspondingly, the same applies to the second contact device and the application of the ground potential thereto. Attached Figure Description

[0048] The embodiments of the present invention are schematically illustrated in the accompanying drawings, and are described in more detail below.

[0049] In the attached image:

[0050] Figure 1 An isolation device for an overvoltage discharge device is shown in its installed state.

[0051] Figure 2 A portion of the isolation device in a non-triggered state is shown.

[0052] Figure 3 A portion of the isolation device during triggering is shown.

[0053] Figure 4 A portion of the isolation device in the triggered state is shown.

[0054] Figure 5 The housing of the isolation device, showing its deformation in a cut-open manner, is shown.

[0055] Figure 6The implementation variations of the isolation device are shown in exploded view, and

[0056] Figure 7 A cross-sectional view shows an implementation variation of the isolation device. Detailed Implementation

[0057] Figure 1 An apparatus with an isolation device 1 is shown. The isolation device 1 is fixedly connected to an overvoltage discharge device 2 at an angle. The overvoltage discharge device 2 has a first accessory body 3 and a second accessory body 4. The two accessory bodies 3 and 4 are separated from each other by an electrical insulating jacket with a shield to prevent weather effects. A varistor 5 is arranged inside the electrical insulating jacket. The varistor 5 is, for example, made of sintered zinc oxide. Inside the jacket, one end of the varistor 5 is in conductive gas contact with the first accessory body 3, and the other end is in conductive gas contact with the second accessory body 4.

[0058] An isolation device 1 is fixedly arranged at an angle on the second accessory body 4. Electrical contact with the isolation device 1 is also achieved via the second accessory body 4. The overvoltage discharge device 2 and the isolation device 1 are part of a grounding device that extends from the phase conductor 6 of the power transmission device to the ground potential 7. Currently, the power transmission device is a so-called overhead line, and the phase conductor 6 of this overhead line can be protected from overvoltages. Such overvoltages can be caused, for example, by lightning strikes. This overvoltage can be reduced by the flow of current through the grounding device. To prevent grounding via the grounding device during normal operation, the overvoltage discharge device 2 is arranged in the path of the grounding device. The varistor 5 of the overvoltage discharge device 2 changes its impedance according to the differential voltage applied between the phase conductor 6 and the ground potential 7. Under normal operating conditions, the impedance of the varistor 5 tends to infinity. When the threshold (limit value, limit) of the differential voltage is exceeded, the impedance of the varistor 5 becomes close to zero. This results in the grounding device being connected. The overvoltage on the phase conductor 6 can be reduced by the flow of current. By successfully reducing the overvoltage, the differential voltage between phase conductor 6 and ground potential 7 is reduced. Varistor 5 can then exhibit high resistance characteristics again.

[0059] In the event of a fault, such as the breakdown of varistor 5, there is a risk of a permanent connection between phase conductor 6 and ground potential 7. This would be an unacceptable grounding in the power transmission device. To overcome this grounding, an isolation device 1 is introduced into the grounding system. The isolation device 1 is used, for example, to permanently interrupt the grounding system by breaking it.

[0060] Below, it should be based on Figure 2 , Figure 3 , Figure 4 Describe the working principle of isolation device 1 in principle. Figure 2 , Figure 3 , Figure 4 Part of the isolation device 1 is shown. The isolation device 1 has a first contact device 8, a second contact device 9, an impedance element 10, a spark gap 11, and a thermally triggered switching element 12. The thermally triggered switching element 12 has a first switching section 13 and a second switching section 14, which are connected by a thermally triggered predetermined break point 15. The first switching section 13 and the second switching section 14 are designed as strips, wherein the two strips overlap each other. In order to connect the first switching section 13 and the second switching section 14 to each other, the thermally triggered predetermined break point 15 is constructed by means of a material fitting bonding process called "welding". The thermally triggered predetermined break point 15 mechanically and electrically connects the first switching section 13 and the second switching section 10. When sufficient energy (in the form of heat) is input to the thermally triggered predetermined break point 15, the thermally triggered predetermined break point 15 is dissolved, and the first switching section and the second switching section 13, 14 are separated from each other.

[0061] First contact device 8 and second contact device 9 are initially arranged in a fixed position relative to each other and connected by a predetermined break point 15. Here, the two contact devices 8 and 9 are held in place by an electrically insulating structure (e.g., a housing). A varistor 5 is electrically connected to the first contact device 8. A first path 16 extends from the first contact device 8 via a spark gap 11 to a thermally triggered switching element 12, and then to the second contact device 9. A second path 17 is provided in parallel with this. The second path 17 extends from the first contact device 8 to the second contact device 9 via an impedance element 10. To position the impedance element 10 between the first contact device 8 and the second contact device 9, a pressure spring is provided, supported on the second contact device 9, where electrical contact is made and the impedance element 10 is pressed against the first contact device 8. Thus, the first path 16 and the second path 17 are arranged electrically in parallel between the first contact device 8 and the second contact device 9. The first contact device 8 provides a first arc root 18 (arc angle). The second contact device 9 provides a second arc root 19 (arc angle). Here, the second arc root 19 is designed to protrude in a bent manner. At the second arc root 19, the second switch section 14 is guided in a sliding, close-fitting manner. Due to the shape of the second arc root 19, the close-fitting second switch section 14 undergoes preferably elastic deformation. Tensile stress is applied to the second switch section 14 by means of a spring element 20. The second switch section 14 is pulled in the direction of the second contact device 9 due to the tension of the spring element 20. The second contact device 9 is fixed by the position and connection of the predetermined thermally triggerable break point 15, supported by the fixed position of the first contact device 8. The thermally triggerable switch element 12 is placed under mechanical prestress. To promote deformation of the second switch section 14, the second switch section has a wrinkled area 21. This wrinkled area 21 is caused, for example, by material weakening. Material weakening can be implemented, for example, by a recess in the second contact device 9.

[0062] A tab is arranged on the second contact device 9. The tab is formed, for example, by bending a section of the second contact device 9. The tab forms a reverse support to press the impedance element 10 onto the first contact device 8 in a spring-loaded manner. Electrical contact between the impedance element 10 and the second contact device 9 is achieved via the tab and the pressure spring used. The impedance element 10 is pressed against the first contact device 8 by the clamping force on it. Thus, a second path 17 is formed between the first contact device 8 and the second contact device 9.

[0063] The following should be based on Figure 2 , Figure 3 and Figure 4The diagram below illustrates the basic operating principle of the device having an isolation device 1 for overvoltage discharge device 2. Under normal operating conditions (no fault in varistor 5, no overvoltage on phase conductor 6), varistor 5 has a high resistance characteristic. Driven by the voltage on phase conductor 6, leakage current flows through varistor 5 to ground potential 7. Here, leakage current flows through isolation device 1. Due to the high impedance of the spark gap 11 in the first path 16, the leakage current flows almost entirely through the second path 17 and the impedance element 10 located in the second path 17 towards ground potential 7 from the first contact device 8 to the second contact device 9. In the event of an overvoltage on phase conductor 6, varistor 5 changes its impedance characteristic to near zero. The leakage current driven by the overvoltage on phase conductor 6 is conducted towards ground potential via the second contact device 9 through the now low-resistance varistor 5, the first contact device 8, and the second path 17. Therefore, the overvoltage is reduced below a threshold, and varistor 5 again changes its impedance characteristic to tend towards infinity. Then, the leakage current is conducted to the ground potential 7 again through the impedance element 10.

[0064] In the event of a permanent and continuous overvoltage and concerning overheating on phase conductor 6, or in the event of a fault within varistor 5, a permanent or very high leakage current may occur from phase conductor 6 to ground potential 7. As the leakage current initially flowing through impedance element 10 increases, so does the voltage drop across impedance element 10. When the voltage drop across impedance element 10 exceeds its limit, the spark gap 11 breaks down. The operating characteristics of spark gap 11 can be determined by its dimensions. Breakdown of spark gap 11 leads to the ignition of an arc within it. In addition to the current flowing through the arc (which also flows to ground potential 7 via the thermally triggered switching element 12 and the second contact device), the thermally triggered switching element 11 is additionally heated by the arc. Due to this heat input, the predetermined thermally triggered break point 15 is weakened and eventually dissolved. Due to the preload applied by the spring element 11 to the second switching section 14 of the heat-triggerable switching element 12, the two switching sections 13, 14 remain spaced apart from each other. As a result, the distance of the spark gap 11 increases and the arc lengthens. Consequently, the heat energy introduced into the isolation device 1 increases additionally (see...). Figure 3 As the two switch sections 13 and 14 move forward relative to each other, the second switch section 14 moves further away from the first switch section 13 and is pulled toward the second contact device 9 via the second arc root 19. Due to the presence of the folded area 21, the second switch section 14 is deformed and supported in the region of the second contact device 9.

[0065] Now, the spark gap 11 exists with an even larger size, causing the burning arc to expand again (compared to...). Figure 4 The burning electric arc further carries heat into the isolation device 1, causing gas expansion. This gas can also be obtained, for example, from the burning plastic material. The expanding gas can cause a pressure load on the isolation device 1, thereby potentially damaging it. The thermal energy of the electric arc can be used to irreversibly damage the isolation device 1. To facilitate the pressure load, the isolation device 1, for example, has a housing (…). Figure 2 , Figure 3 , Figure 4 (Not shown in the image), the housing was damaged due to increased internal pressure. As a result, isolation device 1 was also damaged. Therefore, an isolation point was created in the grounding device from phase conductor 6 to ground potential 7. The unwanted leakage current was interrupted through the isolation point.

[0066] Based on Figure 1 , Figure 2 , Figure 3 , Figure 4 After describing the working principle of the equipment with overvoltage discharge device 2 and isolation device 1, it should be based on... Figure 5 , Figure 6 and Figure 7 The structure of isolation device 1 will be described in more detail. Figure 5 , Figure 6 and Figure 7 The implementation variations of the isolation device 1 are shown respectively.

[0067] based on Figure 2 , Figure 3 , Figure 4 The illustration, Figure 5 A perspective view of isolation device 1 is shown, which isolation device in Figure 2 , Figure 3 , Figure 4 Partially shown in the middle. Figure 5 The image shows a first shell section 22 designed as a half-shell. The first shell section 22 is supplemented by a second shell section 23 (see [reference]). Figure 6 Two housing sections 22 and 23 are part of a housing that positions the components of the isolation device 1 relative to each other. The housing or housing sections 22 and 23 are made of an electrically insulating material, such as plastic. On the end face side, the first contact device 8 and the second contact device 9 are inserted into the housing and are angularly fixed to each other. Figure 5 As can be seen, the second contact device 9 has an arched clamping area that allows for elastic deformation and contact when clamping force is applied in the axial direction 24. The impedance element 10 is inserted into a recess that causes the impedance element 10 to press against the first contact device 8. Furthermore, a recess is provided so that a pressure spring can apply a clamping force to the impedance element 10.

[0068] In the axial direction 24, the first arc root 18 and the shoulder of the first switch section 13 engage with each other within the electrically insulating section of the intermediate housing. Thus, the first switch section 13 can be pressed against the first arc root 18 of the first contact device 8 by the spring element 20. (As from...) Figure 5 As can be seen, the first switch section 13 has an increased wall thickness relative to the second switch section 14. Furthermore, the first switch section 13 has an increased width relative to the second switch section 14. Except for the overlap of the shoulder of the first switch section 13 and the first arc root 18, the first switch section 13 is designed to be inserted laterally into the housing or corresponding housing sections 22, 23. Figure 5 It can also be seen that a recess is provided in the second switching section 14 to form a pleated area 21. The housing surrounds the two paths 16 and 17 in a semi-shell manner on the periphery. A channel 25 is provided on the periphery of the housing. The internal space for accommodating the impedance element 10, the spark gap 11, the thermally triggered switching element 12, etc., is connected to its surrounding environment through the channel 25.

[0069] Figure 6 based on Figure 5 The illustration further shows a second housing segment 23, which engages with the first housing segment 22 substantially in a transverse direction (joining direction) relative to the axial direction 24. Due to the transverse alignment of the joining directions between the two housing segments 22, 23, components disposed inside the housing can be secured to the protrusion in the axial direction 24.

[0070] The shell is surrounded by 26 (in) Figure 6(See exploded view). The cover has a first sleeve section 27 and a second sleeve section 28. In the assembled state of the two sleeve sections 27 and 28, the cover 26 completely surrounds the housing circumferentially. The resulting joint gap can be at least partially filled with a friction-reducing agent. This friction-reducing agent makes it easier to join and loosen the sleeve sections 27 and 28. In addition, an improved sealing effect can be achieved. For example, grease or oil can be used as the friction-reducing agent. The two sleeve sections 27 and 28 are equipped with overlapping sections designed to be complementary in shape, so that the two sleeve sections 27 and 28 can be interlocked with each other, and here surround and close the housing together with the paths 16 and 17 located therein. In order to secure the two sleeve sections 27 and 28, a locking lug is provided on the second sleeve section 28. The locking lug is used to engage with the complementary shoulder of the first sleeve section 27. Due to the radial distribution of multiple locking lugs on the circumference of the second sleeve section 28, an anti-torsion device is provided. The anti-torsion device can be additionally supported by the guide groove 29 and the corresponding groove nut. Furthermore, a resilient sealing element 30 is provided to seal the engagement gap between the two sleeve sections 27, 28. The sealing element 30 can be wetted with a friction-reducing agent (as described above), thereby reducing friction and providing an improved sealing effect.

[0071] On the opposite end faces of the sleeve sections 27 and 28, the sleeve sections are passed through and sealed by conductive through-holes 31 and 32. The conductive through-holes 31 and 32 are, for example, bolts with bolt heads, wherein the bolt heads are oriented in the direction of the first contact device 8 or the second contact device 9, respectively. When the sleeve sections 27 and 28 are joined to form the surrounding cover 26, the housing is enclosed. The engagement gap between the cover 26 and the housing is connected to the internal space of the housing via a channel 25. In the event of an electric arc inside the housing, expanding gas can flow into the engagement gap via the channel 25. Overpressure at the engagement gap causes the cover 26 or the sleeve sections 27 and 28 to widen. Thus, in the event of a triggering event, a simplified loosening of the cover 26 or the sleeve sections 27 and 28 is possible.

[0072] Figure 7A cross-sectional view of an embodiment of the isolation device 1 is shown. Two sleeve sections 27, 28 are connected to each other via a locking connection. An annular elastic sealing element 30 inserted into a groove ensures that the sleeve sections 27, 28 are sealed to each other. Mechanical and electrical contact with the isolation device 1 can be achieved through through-pieces 31, 32 protruding in opposite directions (relative to the axial direction 24). Corresponding contact is made by abutting against the first contact device 8 or the second contact device 9 via bolt heads of through-pieces 31, 32 located inside the housing 26. Due to the curved, elastically deformable design of the contact surface of the second contact device 9, components arranged inside the housing can be elastically clamped and electrically contacted between the first and second contact devices via the contact areas of the first contact device 8 or the second contact device 9 through the through-pieces 31, 32.

Claims

1. An apparatus having an isolation device (1) for an overvoltage discharge device (2), the isolation device having a first contact device (8) and a second contact device (9), a first path (16) arranged between the first contact device (8) and the second contact device (9), the first path (16) having a thermally triggerable switching element (12), Its features are, A second path (17) having an impedance element (10) is arranged electrically in parallel with the first path (16) between the first contact device (8) and the second contact device (9), wherein a spark gap (11) is arranged in the first path (16), and the thermally triggerable switching element (12) has a first switching section (13) and a second switching section (14) which are electrically connected to each other via a predetermined thermally triggerable break point (15).

2. The device according to claim 1, Its features are, A spring element (20) is used to apply a preload force, which presses the second switch section (14) against the second contact device (9).

3. The device according to claim 2, Its features are, The preload force acts on the first switch section (13) or the second switch section (14) parallel to the axis (24) extending from the first contact device (8) to the second contact device (9).

4. The device according to claim 2 or 3, Its features are, The first switch section (13) is pressed against the first contact device (8) by the spring element (20) with the insulating section sandwiched in the middle.

5. The device according to any one of claims 1 to 3, Its features are, The device has a housing with a first housing section (22) and a second housing section (23), in which the first contact device (8), the second contact device (9) and the switching element (12) are embedded, wherein the engagement axis between the first housing section (22) and the second housing section (23) is oriented transversely to the axis (24) extending from the first contact device (8) to the second contact device (9).

6. The device according to claim 5, Its features are, The housing is surrounded by a cover (26), which secures the first housing section and the second housing section (22, 23) relative to each other.

7. The device according to claim 6, Its features are, The cover (26) surrounds the housing in a sleeve manner, wherein the first sleeve section (27) and the second sleeve section (28) are joined together in an insert manner.

8. The device according to claim 6, Its features are, The internal space defined by the housing is connected to the engagement gap located between the housing and the cover (26) via at least one channel (25).

9. The device according to claim 7, Its features are, The first sleeve section (27) has a first conductive through-hole (31) that is electrically connected to the first contact device (8), and the second sleeve section (28) has a second conductive through-hole (32) that is electrically connected to the second contact device (9).

10. The device according to any one of claims 1 to 3, Its features are, The first switch section (13) has a greater wall thickness than the second switch section (14).

11. The device according to any one of claims 1 to 3, Its features are, The first switch section (13) has a wider width than the second switch section (14).

12. The device according to any one of claims 1 to 3, Its features are, The second switch section (14) has a pleated area (21).

13. The device according to any one of claims 1 to 3, Its features are, The second contact device (9) has an arc root (19).

14. The device according to any one of claims 1 to 3, Its features are, The first contact device (8) is electrically connected to the overvoltage discharge device (2), or the second contact device (9) is electrically connected to the overvoltage discharge device (2).

15. The device according to any one of claims 1 to 3, Its features are, The second contact device (9) is subjected to a ground potential (7) or the first contact device (8) is subjected to a ground potential (7).

16. The device according to claim 12, Its features are, The folded area (21) is designed in the form of a perforated area.

17. The device according to claim 14, Its features are, The first contact device (8) is carried by the overvoltage discharge device (2), or the second contact device (9) is carried by the overvoltage discharge device (2).

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