Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
  • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
  • H01C7/12—Overvoltage protection resistors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H37/00—Thermally-actuated switches
  • H01H37/74—Switches in which only the opening movement or only the closing movement of a contact is effected by heating or cooling
  • H01H37/76—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
  • H01H37/761—Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material with a fusible element forming part of the switched circuit

Definitions

• Surge arrester with a housing and at least one diverting element, in particular a varistor
• the invention relates to a surge arrester having a housing and at least one diverting element, in particular a varistor, and a separating device for separating the diverter element or elements from the network, wherein the divider device comprises a separating point, in particular soldering point, which extends into the electrical connection path inside the diverter is involved, wherein via the solder joint, a movable conductor portion or a movable conductive bridge with the diverter on the one hand and the conductor portion or the bridge on the other hand connected to a first electrical outer terminal of the arrester, and comprising a biasing force generating means, such as a spring, wherein the related Force vector acts on the conductor section or the bridge in the separation direction, according to the preamble of patent claim 1.
• the divider device comprises a separating point, in particular soldering point, which extends into the electrical connection path inside the diverter is involved, wherein via the solder joint, a movable conductor portion or a movable conductive bridge with the diverter on
• Overvoltage arresters based on varistors generally have an internal disconnecting device in the low-voltage range.
• This internal separation device consists for example of a combination of a thermal separation device and a predetermined breaking point for high currents.
• This predetermined breaking point represents a defined reduction of the connection cross section of the varistor with a certain melting integral value.
• FIG. 1 The basic design of a separating device, which is often realized by a solder joint between the varistor and a movable, spring-loaded contact pressure, shows the schematic diagram of FIG. 1.
• the disc-shaped varistor 1 shown there is in series with the separating device 2, as a switch symbolizes, switched.
• a biasing force F acts on the separating device. If the solder 5 melts at the connection point, then the electrical contact between the varistor connection 6 and the external connection 7 is removed via the separating strip 3.
• the geometric bottleneck with a defined melting integral value is symbolized by the reference numeral 4.
• the thermal separation device Upon gradual heating of the varistor, e.g. due to aging or a slight increase in voltage, the thermal separation device generally responds after several seconds. A solder which fixes the separating device melts, whereby the contacts under spring force undergo an opening process. The varistor has a high resistance in this case of error, whereby the current through the varistor is severely limited. As a rule, the separating device can easily interrupt these currents and thus safely disconnect the overloaded arrester from the mains, without a further separate overvoltage protection device responding or being required. The power supply of the consumer is therefore not interrupted or disturbed. All that needs to be done is to replace the defective surge arrester during maintenance.
• the thermal disconnecting device can, on the one hand, lead to a delayed disconnection or else the melting integral value of the constriction is reached, whereby it melts and separates the arrester from the mains.
• EP 0 046 545 A1, DE 28 53 697 A1 or EP 0 862 255 A1 or EP 1 447 831 A1 show the combination of a surge arrester with a mechanical switching device which performs the actual disconnection function. Although the switching capacity of such a separation device is sufficiently high, the effort and space required is considerable. Also, the coupling with the thermal tripping function is structurally difficult.
• DD 239 488 or US 6,430,019 Bl disclose the use of an insulating slider, which is moved after the response of the thermal separating device between the two connectors.
• a disadvantage of this solution is that the movement of the slider can be hindered by the melting behavior and the residues of the solder of the thermal contact point, whereby the speed of the arc extension is undefined.
• the insulating slide can be coated by the liquid solder conductive and there is a risk that the arc cuts through the slide or causes its thermal destruction before a sufficient arc extension has been achieved.
• the basic idea of the invention is thus to reduce the residual current which may possibly flow by deliberately commutating this fault current into a separate erase path, this erase path of the separator being connected in parallel or connected in parallel in dependence on certain conditions.
• the fault current is prevented after the opening of the separation distance or commutated in the mentioned parallel branch and thus deleted.
• Ausgestaltend there is the possibility in the path of movement of the conductor section or the bridge, which are part of the separation device, to arrange a conductive element, the first end comes in triggered disconnector with the conductor portion or the bridge in contact, the second end with a second external electrical connection in Connection stands and the conductive element comprises a switching device or is designed as a switching device.
• This embodiment leads to a safe fail-safe behavior by achieving a targeted short circuit of the discharge element.
• the aforementioned embodiment ensures that at a predetermined time, the switching device opens, whereby the fault current is interrupted. After the shutdown process, the defective overvoltage protection device is disconnected from the circuit to be protected and the power supply is maintained. The canceled short circuit allows maintenance personnel to measure a voltage and replace the arrester without danger.
• the commutation branch provided parallel to the separating device can be permanently connected electrically in parallel to the separating device.
• At least one voltage-switching or voltage-limiting element can be connected in series.
• Another essential to the invention approach is to provide a so-called target electrode in the separation distance of the discharge element arranged in series with the separating device, which is connected to the Kommut istszweig.
• a so-called target electrode in the separation distance of the discharge element arranged in series with the separating device, which is connected to the Kommut istszweig.
• the designed to achieve a targeted short circuit ausgestaltend conductive element can also be used later in the arrester to realize in addition to a separation and the aforementioned short-circuit fail-safe function.
• an insulating pad may be arranged between the conductive element and the conductor section or the bridge, or the conductive element has a detachable insulating cover at least at its first end.
• the conductive element may be formed as a fuse, but also have a power semiconductor or form a circuit with a power semiconductor, wherein the power semiconductor is transferred after passing a short-circuit current by means of an initial pulse in the open state.
• the conductive element is further ausgestaltend in cross-section dimensioned such that after passing a short-circuit current is carried out a separation of the conductive connection.
• Fig. 1 is a schematic diagram of a series circuit of a varistor with disconnecting device and a possible structural arrangement of this series circuit according to the prior art
• FIG. 2a shows a block diagram of the solution according to the invention with a commutation branch which is permanently connected in parallel to the separating device;
• Fig. 2b shows an arrangement similar to that of Fig. 2a, but with the ability to connect the Kommutêtszweig separately, and
• Fig. 3 shows an embodiment of the commutation branch with a target electrode, i. not continuous parallel connection with respect to the separating device.
• the separation device 2 comprises a solder joint, not shown in detail, which is integrated in the electrical connection path AB of the arrester, wherein via the solder joint, a movable conductor portion or a movable conductive bridge (symbolized as a switch) with the diverter 1 on the one hand and the conductor section or the bridge on the other hand connected to a first external electrical connection of the arrester.
• a biasing force generating means symbolized by F, For example, a spring, present, wherein the relevant force vector acts on the conductor section or the bridge in the separation direction.
• a commutation branch or commutation path 8 is present which comprises a series connection of a fuse 10 and a voltage-switching element 11.
• the Kommut istszweig 8 is the separator 2 constantly connected in parallel. In the case when the severing device 2 opens, the fault current commutates into the branch 8. This branch 8 carries the current until there is a sufficient separation distance and the arc is safely extinguished. Thereafter, the parallel branch is switched high impedance, e.g. by activating fuse 10, and the flowing current is finally erased.
• FIG. 2b shows a variant embodiment according to which the connection of the commutation branch 8 is effected, for example, by voltage-dependent takes place or else by a mechanical movement of a switch.
• the commutation branch 8 is activated at all loads which lead to the opening of the separating device. If this is undesirable or if the commutation branch 8 is to be activated only in the overload case of the separating device 2, this can be realized according to the embodiment according to FIG.
• the movable connecting element of the separating device 2 is guided past or past a target electrode 12.
• the target electrode 12 is arranged such that the distance between the fixed terminal of the varistor and the target electrode 12 under normal switch-off conditions is sufficient for reliable isolation of the varistor 1.
• the commutation branch 8 can be realized by a parallel connection of a fuse 10 of small size and low nominal current intensity.
• the fuse voltage-switching and voltage-limiting switching elements in series.
• the resulting fault current commutates to the fuse. This leads the fault current over a period of time which is sufficient for extinction and deionization of the switching path. After that, the fuse switches off the power.
• the switching voltage of the fuse 10 may in this case the dielectric strength of the actual switching path, i. the switching path of the separator, do not exceed.
• reversible fuses or PTC elements can be used. Also, the use of electronic components for shutdown and commutation is possible.
• a further separating device may be provided in the commutation path, which may be e.g. disconnects the PTC element when reaching a certain temperature, whereby the arrester is finally fully released from the network by a real separation distance.
• the varistor in the event of a fault, the varistor is short-circuited, there is the risk that in a permanent short circuit in the case of application of such Kochnapssabieiters in transformerless inverters result in photovoltaic applications problems, due to flowing back currents.
• the replacement of a short-circuit surge absorber can cause an arc hazard, since in the aforementioned photovoltaic applications, a current flow from the generator takes place.
• a switching device is present in the short circuit branch.
• the actual thermal separation device is actuated and moves the separation contact to the conductive element, with the result of reaching a short-circuit state.
• the resulting light arc is guided by the contact elements and extinguishes automatically when reaching the short-circuit contact.
• the switching device provided in the short-circuit path then opens and interrupts the fault current.
• a switching device mechanical switching devices, fuses, but also power semiconductors can be used. The use of spark gaps as a switching device is conceivable. After the shutdown of the switching device, which is located in the short circuit path, the defective surge arrester arrangement is separated from the actual circuit and it remains the supply.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Emergency Protection Circuit Devices (AREA)
• Details Of Resistors (AREA)
• Thermistors And Varistors (AREA)

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• 2008
  • 2008-03-10 DE DE102008013448.1A patent/DE102008013448B4/de not_active Expired - Fee Related
  • 2008-10-30 AT AT08846127T patent/ATE512444T1/de active
  • 2008-10-30 WO PCT/EP2008/064707 patent/WO2009056587A1/fr active Application Filing
  • 2008-10-30 EP EP08846127A patent/EP2208208B1/fr active Active

Non-Patent Citations (1)

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