EP3306622A1 - Overvoltage protection element - Google Patents

Abstract

Shown and described is an overvoltage protection element (1) with a housing (2), with a varistor (3) arranged in the housing (2), with an electrically conductive connecting element (4) and with at least one insulating separating element (5), wherein the varistor (3) has a first terminal (6) and a second terminal (7), wherein the insulating separator (5) is movably arranged relative to the first terminal (6) of the varistor (3) so as to be in a first position in the normal state of the overvoltage protection element (1) a first end (8) of the electrically conductive connecting element (4) to the first terminal (6) of the varistor (3) is electrically connected and the insulating separating element (5) in is held in its first position, and wherein upon reaching a critical state of the varistor (3) the connection between the first end (8) of the electrically conductive connecting element (4) and the first terminal (6) of the varistor (3) and the insulating separating element (5) is moved by a force in its second position, in which a portion of the separating element (5) between the first end (8) of the electrically conductive connecting element (5) 4) and the first terminal (6) of the varistor (3) is arranged. In the overvoltage protection element (1) a secure separation from the network is thereby ensured that the at least one insulating separating element (5) is formed so that when separating the connection between the first end (8) of the electrically conductive connecting element (4) and first connection (6) of the varistor (3) resulting arc (10) is placed in at least one partially closed chamber (11).

Description

The invention relates to an overvoltage protection element having a housing, having a voltage limiting component arranged in the housing, having an electrically conductive connecting element and having at least one insulating separating element, wherein the overvoltage limiting component has a first terminal and a second terminal and the insulating separating element is relative to the first terminal of overvoltage limiting component is movably arranged so that it can be moved from a first position to a second position.

Surge protection is understood to mean the protection of electrical and electronic equipment from excessive electrical voltages. The necessary measures for the protection of plants and equipment are divided into different levels according to the expected overvoltages. The protection devices for the individual stages differ in particular by the amount of the Ableitvermögens and the protection level. Surge arresters of the second protection stage, so-called type 2 surge arresters, have predominantly varistors as overvoltage limiting protective elements which enable a high discharge capacity with low residual voltage. In addition, however, gas-filled surge arresters or diodes can be used as overvoltage limiting protective elements. In the normal state, varistors have relatively low leakage currents, which, however, can increase over time due to aging or short-term overload. The heating involved in such cases can lead to thermal destruction of the varistor, which in turn can cause damage to adjacent components or devices. Therefore, a thermal destruction of the varistor must be prevented, which are used in the prior art thermal separating devices that separate the varistor from the network to be protected when a limit temperature is exceeded.

From the DE 42 41 311 C2 is an overvoltage protection element is known, which has a thermal separation device for monitoring the state of a varistor. The overvoltage protection element has two connection contacts for connection to the current path to be protected. The first connection contact is connected via a flexible conductor with a conductive connecting element, the end facing away from the flexible conductor is connected via a solder joint with a connection tab provided on the varistor. The other connection contact is connected via a flexible conductor fixed to a second terminal lug on the varistor. The conductive connecting element is acted upon by a spring system with a force that causes the connecting element is linearly moved away during the separation of the solder joint from the terminal lug, so that the varistor is electrically disconnected under thermal overload. In order to erase an arc that occurs when opening the separation point, it is necessary for the connection element to have as large a distance as possible from the connection lug after separation of the solder connection, which necessitates a relatively large construction volume of the overvoltage protection element.

The thermal separation devices used in the known overvoltage protection elements, which are based on the melting of a solder joint, have to fulfill several tasks. In the normal state of the overvoltage protection element, d. H. in the non-separated state, a secure and good electrical connection between the associated terminal contact and the overvoltage limiting component must be ensured. When a certain limit temperature is exceeded, the separation point must ensure a safe separation of the overvoltage limiting component as well as a permanent insulation resistance and tracking resistance. If the overvoltage protection elements should have the smallest possible dimensions so that the overvoltage protection devices, for example, do not exceed the dimensions specified for DIN rail devices, this will mean that they only have a relatively low extinguishing capacity when used in DC voltage networks.

The US Pat. No. 6,430,019 B1 discloses a surge arrester having a thermal severing device in which one end of a resilient contact tab is connected via a solder joint to a terminal of the varistor. If there is an inadmissible heating of the varistor, this leads to a melting of the solder joint, so that the end of the deflected contact tongues wegfedert from the terminal of the varistor. At the same time moves an insulating separator between the contact blade and the varistor to a possibly extinguishing pending arc. Since the insulating separating element has smaller dimensions than the varistor, only a portion of the varistor is shielded by the separating element, so that it can not be ruled out that the arc or the plasma forming in the region of the contacts closes again around the separating element, so that a current continues to flow across the varistor.

An initially described overvoltage protection element is also known from DE 20 2014 103 262 U1 known. In this overvoltage protection element, a gas-filled surge arrester is used as overvoltage limiting component, so that also large pulse currents can be dissipated via this overvoltage protection element. The overvoltage protection element furthermore has an insulating separating element which can be displaced from a first position to a second position by the force of a spring element. In the case of the overvoltage protection element, the first connection contact is permanently electrically connected to the first electrode of the surge arrester. In the normal state of the overvoltage protection element, ie when the surge arrester is not heated inadmissible, the first end of an electrically conductive connecting element via a thermally disconnecting connection to the second electrode of the surge arrester is electrically connected, while the second end of the connecting element is conductively connected to the second terminal contact. In the normal state of the overvoltage protection element, moreover, the insulating separating element is held in its position by the connection realized between the first end of the conductive connecting element and the second electrode of the surge arrester.

If the surge arrester has heated up so much due to a permanent overloading of the overvoltage protection element that the limit temperature is exceeded, the solder connection melts and thus the thermal connection between the electrically conductive connecting element and the associated electrode of the surge arrestor is severed. The insulating separator is then moved by the force of the spring element to its second position. In this position of the separating element is a portion of the separating element between the first end of the electrically conductive connecting element and the associated Electrode of the surge arrester arranged so that the direct connection between the conductive connection element and the surge arrester is disconnected. Again, however, there is a risk that due to the still existing between the end of the connecting element and the associated terminal of the surge arrester an arc remains, so that further a current flows through the surge arrester, which can lead to thermal destruction of the overvoltage protection element.

The present invention is therefore based on the object to provide a previously described overvoltage protection element, in which a secure separation of the overvoltage protection element ensured by the network and thus a thermal destruction of the overvoltage limiting component is prevented.

This object is achieved in the overvoltage protection element with the features of claim 1, characterized in that the insulating separating element is formed so that when disconnecting the electrical connection between the first end of the electrically conductive connecting element and the first terminal of the overvoltage limiting device pending arc in an at least partially closed chamber is spent. The deflection of the arc by the insulating separator first causes the length of the arc to increase, thereby increasing the arc burning voltage, ie, the voltage required to maintain the arc. In addition, the plasma present in the region between the first end of the electrically conductive connection element and the first connection of the overvoltage limiting component is also transported out of the region between the contacts with the arc. There is thus a guided by the movement of the isolated separator guided discharge of the plasma from the area between the contacts, which also leads to an increase in the arc voltage. As a result, an arc which arises when the connection between the conductive connection element and the connection of the overvoltage limiting component is opened is reliably extinguished and a renewed ignition of an arc reliably prevented.

The force by which the insulating separating element is moved from its first position to its second position can be generated, for example, by a spring element, which is connected to the separating element or acts on the separating element. Alternatively, the force could also be applied by an intumescent material which spreads upon reaching a certain temperature and thereby spills the insulating separator from its first position to its second position.

Initially, it was stated that in the normal state of the overvoltage protection element, the first end of the electrically conductive connection element is electrically conductively connected to the first terminal of the overvoltage limiting component. The contact between the end of the connecting element and the terminal of the overvoltage limiting component can be formed, for example, as a pressure contact. For this purpose, the connecting element can be pretensioned or pressed against the connection of the overvoltage limiting component with a force, for example a spring force. When a critical state of the overvoltage limiting component is reached, the connection is then disconnected by at least the first end of the electrically conductive connection element being moved away from the terminal of the overvoltage limiting component. A critical state of the overvoltage limiting component can be determined for example by a current measurement or a Temeperaturmessung.

Preferably, however, the connection is designed as a thermally disconnecting connection, which then disconnects when the temperature of the overvoltage limiting component exceeds a limit temperature, so that it is a thermal separation device. As is customary in the prior art, the thermally disconnecting connection is preferably also realized by a solder connection in the overvoltage protection element according to the invention. If the overvoltage-limiting component, ie the surge arrester, has become so hot due to permanent overloading that a predetermined limit temperature is exceeded, the solder connection between the terminal of the surge arrester and the conductive connection element melts. In addition, the insulating separator is by a force, preferably by the force at least one spring element, between the terminal of the surge arrester and the associated end of the conductive connecting element moves.

According to a first preferred embodiment of the overvoltage protection element according to the invention, the insulating separating element is movably arranged in a housing whose volume is greater than the volume of the separating element, that is, the interior of the housing is only partially filled by the insulating separating element. The area inside the housing, in which the insulating separating element is not arranged in the normal state of the overvoltage protection element, thereby forms the chamber into which an arc which is present when the electrical connection between the first end of the electrically conductive connecting element and the first terminal of the overvoltage limiting component is disconnected the separating element is spent. In addition, the housing, which may consist of several parts, an opening through which the first end of the electrically conductive connecting element is electrically conductively connected to the first terminal of the surge arrester in the normal state of the overvoltage protection element.

In the overvoltage protection element according to the invention, the movement of the insulating separating element from its first position to its second position not only separates the connection between the conductive connecting element and the overvoltage limiting component, but also deflects the arc into the chamber in the housing. When separating connection between the first end of the electrically conductive connecting element and the first terminal of the surge arrester, the plasma present in the region of the contacts is pressed into the chamber in the housing. For this purpose, the end face of the insulating separating element facing the first terminal of the overvoltage limiting component may be designed differently, for example in the form of a wedge or a funnel.

According to one embodiment of the invention, the insulating separator has an opening through which in the normal state of the overvoltage protection element, the first end of the electrically conductive connecting element with the first terminal of the surge arrester is electrically connected. The opening in the insulating separating element is formed corresponding to the opening in the housing, so that in the normal state of the overvoltage protection element, the first end of the electrically conductive connecting element extends through the opening in the housing and the opening in the insulating separating element and preferably via the thermally disconnecting compound, For example, a solder joint is connected to the terminal of the surge arrester.

In a preferred embodiment of the overvoltage protection element according to the invention, the housing in the region of the chamber has an outlet opening, via which the plasma pressed by the separating element into the housing can flow off. This advantageously leads to the plasma being able to escape from the housing in a controlled manner, which further reduces the risk of a renewed ignition of an arc. In addition, the outlet opening in the housing ensures that the pressure in the housing does not become too great when the insulating separator moves from its first position to its second position, thereby forcing the plasma into the housing. This prevents damage to the housing. The outlet opening is preferably located in the wall of the housing, to which the separating element is moved when it is moved from its first position to its second position.

According to a further particularly advantageous embodiment of the invention, at least one channel is formed in the insulating separating element, which is open on the side facing the chamber. The insulating separator is thus formed as a kind of hollow body. If, after disconnecting the connection between the first end of the electrically conductive connecting element and the first terminal of the overvoltage limiting component, the insulating separating element is moved from its first position to its second position, then - as in the case of a closed separating element - a pending arc enters the chamber pressed in the housing. In this case, a part of the plasma is pressed into the chamber in the housing, while another part of the plasma - opposite to the direction of movement of the separating element - flows into the channel in the separating element.

This also effectively removes conductive plasma from the area between the opening contacts.

According to a variant of this embodiment, a web or a partition wall is formed within the housing, which extends in the direction of movement of the insulating separating element, so that is subdivided by the web or the partition, the chamber in the housing into two sub-chambers. If the insulating separating element is moved from its first position to its second position, then the web or the dividing wall dips into the channel in the separating element. In this case, a plurality of channels and within the housing corresponding to a plurality of webs or partitions may be formed in the insulating separating element, so that a plurality of sub-chambers are formed in the housing accordingly. The housing then has a comb-like structure.

If the insulating separating element has at least one channel into which plasma can flow from its first position to its second position during the movement of the separating element, the separating element preferably has at least one outlet opening through which plasma can flow out of the insulating separating element. The outlet opening may be formed, for example, on the side facing away from the chamber in the insulating separating element. The channel formed in the separating element is thus connected via the outlet opening to the interior of the housing, wherein the housing preferably also has an outlet opening. This can be arranged opposite the outlet opening in the separating element or also on another side wall. In such an embodiment of the overvoltage protection element plasma can flow opposite to the direction of movement of the insulating separating element through the channel in the separating element and escape controlled via the outlet opening in the housing from the housing.

Between the inner wall of the housing and the outer surface of the insulating separating element, an outlet channel can be formed through which plasma can flow from the channel in the separating element through the outlet opening in the separating element to the outlet opening in the housing. In order to increase the cooling of the hot plasma even further, a medium for cooling the outflowing plasma can be arranged in the outlet channel, which preferably also serves to damp the flow of the plasma. This may be, for example, a material with a honeycomb structure, which has a high porosity. Likewise, it may also be a granular material, for example sand or gravel.

In the embodiment in which the insulating separating element is movably arranged in a housing, the insulating separating element and the housing are matched to one another such that the cross section of the interior of the housing is only slightly larger than the cross section of the separating element. This results in that between the inner wall of the housing and the outer surfaces of the insulating separator only relatively narrow gaps exist, in which the arc can propagate. This leads to an increase in the pressure in the gaps, which leads to an increase in the arc-burning voltage. Moreover, if the housing and / or the insulating partition at least partially consists of a gaseous material, this also means that the arc is blown in the gap between the insulating separator and the inner wall of the housing by outflowing material and thus cooled. This also promotes the intentional extinction of the arc.

In order for the housing and the insulating separating element to safely withstand the high temperatures or high pressures which may occur, the housing, and preferably also the insulating separating element, consists of a mechanically and thermally stable material, preferably of a fiber-reinforced material.

The vote of the interior of the housing on the cross section of the separating element also results in that the insulating separating element is guided during its movement from its first position to its second position in the housing. In addition, between the insulating separating element and the inner wall of the housing, a guide may be formed, for example in the form of guide ribs and guide grooves, which are formed corresponding to one another on the insulating separating element or in the housing.

As has been described above, the overvoltage protection element according to the invention has at least one insulating separating element which can be designed accordingly. According to one embodiment of the invention, the overvoltage protection element not only a separating element but a plurality of insulating separating elements, which are each arranged movable relative to the first terminal of the overvoltage limiting component and preferably acted upon by a force by which they can be brought from a first position to a second position are.

If the overvoltage protection element has a plurality of insulating separating elements, then it is preferably provided that each separating element is movably arranged in a housing or a housing section, wherein each housing or each housing section has an opening and the openings are arranged relative to one another such that in the normal state of the overvoltage protection element End of the electrically conductive connecting element is electrically conductively connected through the openings with the first terminal of the surge arrester. The individual insulating separating elements thus form a kind of series connection, so that the individual separating elements are moved after breaking the connection in each case in its second position, in which the separating elements between the first end of the electrically conductive connecting element and the first terminal of the overvoltage limiting component are arranged. If the overvoltage protection element has, for example, two insulating separating elements, in the separated state of the connection, both insulating separating elements are arranged between the first end of the electrically conductive connecting element and the first terminal of the surge arrester.

Preferably, in the normal state of the overvoltage protection element, at least two insulating separating elements are arranged essentially on different sides of the first terminal of the overvoltage limiting component such that the directions of movement of these separating elements are opposite to one another. Arranged essentially on different sides of the first connection means that at least the larger part of the insulating separating elements is arranged on different sides. A smaller part of the insulating separating elements can thus also be arranged on the same side of the first terminal, for example when in each case an opening is formed in the separating elements, through which the first end of the connecting element extends to the first connection in the normal state of the overvoltage protection element. Such separators thus extend in the normal state on both sides of the first terminal, but the larger part is arranged on one side of the terminal.

If the overvoltage protection element has two insulating separating elements, this means, for example, that in the normal state of the overvoltage protection element the first separating element is arranged on the left side of the connection and the second separating element is arranged on the right side of the connection of the overvoltage limiting component. When disconnecting the connection then the first separator is moved within its housing from left to right and the second separator within its housing from right to left. As a result, the length of the arc resulting from severing the thermal connection is further increased and the plasma is forced through the insulating separators in opposite directions into two chambers.

The advantageous embodiments of the separating element or of the housing described above in connection with an insulating separating element can each also be realized when the overvoltage protection element has a plurality of insulating separating elements and a plurality of housings or a plurality of housing sections. For example, an outlet opening can in each case be formed in the housings or in the housing sections, so that plasma can escape in controlled manner through the outlet openings-in different directions-out of the housing. The individual housings are preferably arranged immediately adjacent to each other, so that the interiors of the housing are separated from each other only by a partition wall, wherein the partition wall is interrupted by the opening for the first end of the electrically conductive connecting element. The individual housings can also be fixedly connected to one another to form a common housing, so that the one housing has a plurality of housing sections in which a corresponding chamber is then formed in each case for the individual separating elements.

According to a further embodiment variant of the overvoltage protection element according to the invention, at least one channel is formed in the insulating separating element, which acts as a chamber into which an arc arising when the thermal connection occurs can be brought about. In this case, the channel is open on the side facing the first terminal of the overvoltage limiting component, and the insulating separating element is movable relative to the first terminal of the overvoltage limiting component such that the first end of the electrically conductive connecting element is in the second position of the insulating separating element in the channel in the separating element is arranged.

In this embodiment of the overvoltage protection element according to the invention, therefore, the insulating separating element in its second position is not located as a whole between the first terminal of the overvoltage limiting component and the first end of the electrically conductive connecting element, but the insulating separating element with its channel via the first end of the electrically conductive Pushed connecting element. The first end of the conductive connecting element is then separated from the first terminal of the overvoltage limiting device by a lower wall bounding the channel. As the insulating separator moves past the first terminal of the overvoltage limiting device, a pending arc is forced into the chamber functioning as a chamber, thereby increasing the length of the arc between the first terminal of the overvoltage limiting device and the first end of the conductive connecting member Usually leads to an extinction of the arc. In addition, an outflow of the forming in the region between the contacts plasma is effected from the active area between the contacts. In this case, the insulating separating element may additionally have at least one outlet opening through which plasma can flow out of the channel in the separating element.

According to a development of this embodiment, a closure element is arranged on the side of the first terminal of the overvoltage limiting component, on which the insulating separation element is not in the normal state of the overvoltage protection element, to which the insulating Separator in its second position with the open side of the channel is present. If the insulating separating element is in its second position, then the open side of the channel is closed by the closing element, so that a possibly still occurring arc is "pinched off" or "cut off". In the second position of the insulating separating element then the first end of the electrically conductive connecting element is completely encapsulated, so that it can not come again to ignite an arc between the connecting element and the first terminal of the surge arrester. In this case, the closure element has a through opening, through which the conductive connection element extends, so that the closure element also serves as a holder for the connection element.

If, in the overvoltage protection element according to the invention, the overvoltage limiting component has a protruding first connection, according to a further refinement of the embodiment variant described last, it is provided that a second channel, which runs parallel to the first channel, is formed in the insulating separation element. The second channel is designed so that during the movement of the insulating separating element from its first position to its second position, the separating element is pushed with its second channel on the protruding connection of the surge arrester. In the second position of the insulating separating element, the first end of the electrically conductive connecting element in the first channel and the connection of the surge arrester in the second channel are then arranged. The terminal and the connecting element are thus enclosed by the insulating separating element, wherein the terminal and the connecting element are located in different channels in the separating element, so that they are separated from each other and electrically insulated.

In order that the insulating separating element can be displaced relative to the first terminal preferably protruding perpendicularly from the surge arrester, the underside of the insulating separating element facing the surge arrester is open in the region of the second channel or the second channel has a slot running in the direction of movement in the underside thereof Slide in connection.

The second channel can - as well as the first channel - be open on the first terminal of the overvoltage limiting component side facing, in which case the insulating separator is arranged in its first position in the direction of movement of the separating element next to the first terminal of the overvoltage limiting component. In this variant, two closure elements are preferably provided such that the open side of the two channels is in each case closed by a closure element when the insulating separating element is in its second position.

Alternatively, the insulating separating element may also be formed such that the first terminal of the overvoltage limiting component is arranged in the first position of the separating element in the second channel, wherein the first end of the electrically conductive connecting element contacts the first terminal of the overvoltage limiting component. For this purpose, the first chamber has a shorter length than the second chamber, so that in the first position of the insulating separating element, the first chamber is arranged in the direction of movement of the separating element next to the first end of the electrically conductive connecting element, while the first terminal of the overvoltage limiting device in the second Channel is arranged.

Also in the embodiment of the overvoltage protection element in which two channels are formed in the insulating separating element, at least one closure element is preferably arranged on the side of the first terminal of the overvoltage limiting component, on which the insulating separating element is not located in the normal state of the overvoltage protection element isolating separator in its second position abuts the open side of the channel.

According to a further advantageous embodiment, the insulating separating element has at least one outlet opening, preferably in the rear wall of the second channel, which in the first position of the insulating separating element is spaced from the first connection of the overvoltage limiting component, so that plasma controlled by the outlet opening from inside the corresponding channel can flow out. This prevents that in the channel in the insulating separating element forms an excessive pressure when the insulating separator is in its second position in which the open side of the channel is closed by the closure element.

In the above-described embodiments of the overvoltage protection element according to the invention, the insulating separating element or the insulating separating elements are designed as a slide, so that the separating element or the separating elements are linearly displaced from the first position to the second position.

Fig. 1

schematische Darstellungen eines ersten Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, von der Seite, in drei verschiedenen Zuständen,

Fig. 2

zwei Varianten eines isolierenden Trennelements und eines das Trennelement aufnehmenden Gehäuses, von der Seite,

Fig. 3

drei Varianten eines isolierenden Trennelements und eines das Trennelement aufnehmenden Gehäuses, von oben,

Fig. 4

zwei Varianten eines isolierenden Trennelements und eines das Trennelement aufnehmenden Gehäuses, aus Blickrichtung A ge-mäß Fig. 1,

Fig. 5

schematische Darstellungen einer Variante des in Fig. 1 darge-stellten Ausführungsbeispiels des erfindungsgemäßen Überspan-nungsschutzelements, mit zwei isolierenden Trennelementen, in drei verschiedenen Zuständen,

Fig. 6

schematische Darstellungen eines zweiten Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, in drei verschiedenen Zuständen,

Fig. 7

schematische Darstelluneng eines weiteren Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, in drei verschiedenen Zuständen,

Fig. 8

schematische Darstellungen eines vierten Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, in drei verschiedenen Zuständen,

Fig. 9

schematische Darstellungen des Überspannungsschutzelements gemäß Fig. 8, in Draufsicht, in drei verschiedenen Zuständen,

Fig. 10

schematische Darstellungen eines fünften Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, in drei verschiedenen Zuständen,

Fig. 11

schematische Darstellungen des Überspannungsschutzelements gemäß Fig. 10, in Draufsicht, in drei verschiedenen Zuständen,

Fig. 12

schematische Darstellungen eines weiteren Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, in drei verschiedenen Zuständen, und

Fig. 13

schematische Darstellungen eines weiteren Ausführungsbeispiels eines erfindungsgemäßen Überspannungsschutzelements, in drei verschiedenen Zuständen.

In particular, there are a variety of ways to design and develop the overvoltage protection element according to the invention. Reference is made to both the claims subordinate to claim 1 and to the following description of preferred embodiments in conjunction with the drawings. In the drawing show

Fig. 1

schematic representations of a first embodiment of an overvoltage protection element according to the invention, from the side, in three different states,

Fig. 2

two variants of an insulating partition member and a housing receiving the partition, from the side,

Fig. 3

three variants of an insulating partition member and a partition receiving housing, from above,

Fig. 4

two variants of an insulating separating element and a housing receiving the housing, from the direction A according to Fig. 1 .

Fig. 5

schematic representations of a variant of in Fig. 1 illustrated embodiment of the overvoltage protection element according to the invention, with two insulating separating elements, in three different states,

Fig. 6

schematic representations of a second embodiment of an overvoltage protection element according to the invention, in three different states,

Fig. 7

Diagrammatic Darstelluneng another embodiment of an overvoltage protection element according to the invention, in three different states,

Fig. 8

schematic representations of a fourth embodiment of an overvoltage protection element according to the invention, in three different states,

Fig. 9

schematic representations of the overvoltage protection element according to Fig. 8 in top view, in three different states,

Fig. 10

schematic representations of a fifth embodiment of an overvoltage protection element according to the invention, in three different states,

Fig. 11

schematic representations of the overvoltage protection element according to Fig. 10 in top view, in three different states,

Fig. 12

schematic representations of another embodiment of an overvoltage protection element according to the invention, in three different states, and

Fig. 13

schematic representations of another embodiment of an overvoltage protection element according to the invention, in three different states.

The figures show schematic representations of various embodiments of an overvoltage protection element 1 with a housing 2, only partially shown in the figures, in which a varistor 3 is arranged as overvoltage limiting component. In addition, the overvoltage protection element 1 still has an electrically conductive connecting element 4 and at least one insulating separator 5, from which in the Fig. 2 to 4 Various variants are shown.

The varistor 3 has a first terminal 6 and a second terminal 7, which are electrically connected to terminal contacts of the overvoltage protection element 1, not shown here, when the overvoltage protection element 1 is in the normal state, that is not disconnected. In the in Fig. 1a illustrated normal state of the overvoltage protection element 1, the first terminal 6 of the varistor 3 is connected to the first end 8 of the electrically conductive connecting element 4 via a thermally disconnecting connection. In the illustrated embodiments, the thermally disconnecting compound is formed as a solder joint 9, which then separates when the temperature of the varistor 3 has reached a limit. As a result of the solder connection 9 present in the normal state of the overvoltage protection element 1, the insulating separating element 5 is held in its first position counter to a force acting on the separating element 5, which force can be generated, for example, by a spring element.

If there is an inadmissible heating of the varistor 3, this leads to a softening of the solder joint 9, which initially results in the first end 8 of the connecting element 4 moving away from the first terminal 6 of the varistor 3. This can be achieved, for example, by virtue of the fact that the connecting element 4 itself is resilient and is deflected out of its relaxed state when it is connected to the connection 4 via the solder connection 9. Alternatively, however, can act on the connecting element 4 and force, which is directed away from the solder joint 9. In addition, the insulating separator 5 is moved from its first position towards its second position as shown in FIG Fig. 1c is shown. Also, the movement of the first end 8 of the connecting element 4 away from the first terminal 6 of the varistor 3 can be supported. In the case of the overvoltage protection element 1 according to the invention, the insulating separating element 5 is now designed such that it presses an arc 10 which arises during the separation of the connection 9 between the first end 8 of the connecting element 4 and the terminal 6 of the varistor 3 into at least one partially closed chamber 11.

The Fig. 2 to 6 show various embodiments of an overvoltage protection element 1 according to the invention, in which the insulating separating element 5 is movably arranged in a housing 12 whose volume is greater than the volume of the separating element 5, so that the housing 12 is filled only in part by the separating element 5. The housing 12 has an opening 13 through which the first end 8 of the electrically conductive connecting element 4 is electrically conductively connected to the first terminal 6 of the varistor 3 via the solder joint 9 in the normal state of the overvoltage protection element 1, as for example Fig. 1a is apparent.

At the in Fig. 1 illustrated embodiment, the insulating separator 5 is in the normal state of the overvoltage protection element 1 on - based on the first terminal 6 of the varistor 3 - left side within the housing 12, while the right side of the housing 12 surrounds the chamber 11, in the separation of the Solder 9 is pressed between the terminal 6 and the connecting element 4 pending arc 10 through the insulating separator 5. This leads - as if Fig. 1c it can be seen - to a significant extension of the arc 10, whereby the arc 10 is deleted. In addition, since the plasma 14 has been pushed out of the active area between the contacts, ie between the first terminal 6 of the varistor 3 and the first end 8 of the connecting element 4, also an otherwise possible reignition of an arc between the contacts is prevented.

Fig. 1b shows schematically the state when the solder joint 9 has separated and the end 8 of the connecting element 4 has detached from the terminal 6 of the varistor 3. Shown here is also the arc 10, which extends between the end 8 of the connecting element 4 and the terminal 6 of the varistor 3 and the plasma 14, which is in the region between the end 8 of the connecting element 4 and the terminal 6 of the varistor third forms. The insulating separator 5 is still shown in the first position, even if a movement of the separating element 5 in the second position, ie in the illustration according to Fig. 1 to the right, already starts when the solder joint 9 separates.

So that during the movement of the insulating separating element 5 from its first position to its second position, the pressure within the chamber 11 in the housing 12 does not become too large, the housing 12 has at least one outlet opening 15 through which plasma 14 can flow out in a controlled manner in Fig. 1c indicated by an arrow. As a result, damage to the housing 12 is prevented by excessively high pressure or too high a temperature due to the plasma 14 deflected into the chamber 11. The outlet opening 15 is preferably located in the wall of the housing 12 to which the separating element 5 is moved when it is moved to its second position. Alternatively or additionally, an outlet opening can also be formed in the other walls of the housing 12, which surround the chamber 11.

The Fig. 2 to 4 show various embodiments of the insulating separator 5 and the housing 12 in which the separator 5 is guided. In Fig. 2 are the housing 12 and the separator 5 - as well as in Fig. 1 - Shown from the side, wherein a side wall of the housing 12 is omitted, so that the arranged in the housing 12 separating element 5 is visible. In Fig. 3 the housing 12 and the separator 5 are shown in plan view, in which case the top of the housing 12 is omitted, so that the separator 5 is visible again.

According to Fig. 2a and Fig. 2b For example, the end face 16 of the insulating separating element 5 facing the first terminal 6 of the varistor 3 or the first end 8 of the connecting element 4 in the normal state of the overvoltage protection element 1 can be designed to be arcuate or wedge-shaped. As seen from the top view Fig. 3c it can be seen, the end face 16 of the separating element 5 may also be funnel-shaped. Likewise, the end face 16 of the insulating separating element 5 may also be straight, as shown in FIGS Fig. 3a and 3b is shown. At the in Fig. 3b illustrated embodiment, the insulating separator 5 has an opening 17 through which the first end 8 of the electrically conductive connecting element 4 is connected via the solder joint 9 with the first terminal 6 of the varistor 3 in the normal state of the overvoltage protection element. For explanation, the first terminal 6 of the varistor 3 arranged below the corresponding opening 13 in the housing 12 is also shown here.

From the two representations according to Fig. 4 , each showing a variant of the insulating separator 5 and the housing 12 from the direction of the chamber 11, it can be seen that the insulating separator 5 and the housing 12 are coordinated so that the cross section of the interior of the housing 12 is only slightly larger than that Cross-section of the separating element 5 is. This results in that between the inner wall of the housing 12 and the top and the bottom of the insulating separator 5 only a very narrow gap, in which the arc 10 can propagate, as in Fig. 1c is shown. In addition, this results in that the separating element 5 is guided in the housing 12 during its movement from the first position to the second position. In order to improve the guide, the insulating separator 5 may further according to Fig. 4a Guide ribs 18 have, to which in the inner wall of the housing 12 corresponding guide grooves 19 are formed. Alternatively, according to Fig. 4b on the inner wall of the housing 12 guide ribs 20 and in the insulating separator 5 corresponding guide grooves 21 may be formed.

Fig. 5 shows a schematic representation of a variant of in Fig. 1 shown overvoltage protection element 1, again in three different states. While in the overvoltage protection element 1 according to Fig. 1 only an insulating separator 5 is provided, the overvoltage protection element 1 according to Fig. 5 two insulating separating elements 5, 5 ', which are each guided in a housing 12, 12' slidably. Both housings 12, 12 'each have an opening 13, 13', wherein the two openings 13, 13 'one above the other, that are aligned, so that in the normal state of the overvoltage protection element 1, the first end 8 of the conductive connecting element 4 through the two Openings 13, 13 'via the solder connection 9 with the first terminal 6 of the varistor 3 is electrically connected.

How out Fig. 5a it can be seen, the two insulating separating elements 5, 5 'are arranged in the normal state of the overvoltage protection element 1 on different sides of the first terminal 6 of the varistor 3. Corresponding to this, the chambers 11, 11 'formed in the two housings 12, 12' are also formed on different sides of the first terminal 6 of the varistor 3, so that the directions of movement of the two separating elements 5, 5 'are opposite to each other. How out Fig. 5c it can be seen, the first, lower separating element 5 is moved during the separation of the solder joint 9 within the housing 12 from left to right, while the second, upper separating element 5 'is moved within its housing 12' from right to left. The two insulating separating elements 5, 5 'thus act as two counter-rotating slides, so that the length of the arcing 10 resulting from the separation of the solder joint 9 is further increased, and the plasma 14 through the two insulating separating elements 5, 5' in opposite directions in the both chambers 11, 11 'in the two housings 12, 12' is pressed. By means of outlet openings 15, 15 'formed on the end faces of the housings 12, 12', the plasma 14 can again escape in a controlled manner, wherein the outlet openings 15, 15 'are also formed on different sides.

In Fig. 6 a schematic representation of another embodiment of an overvoltage protection element 1 according to the invention is shown, wherein in this embodiment in the insulating separator 5, a channel 22 is formed, which is open on the chamber 11 and the first terminal 6 of the varistor 3 facing side. Is the insulating separator 5 after the separation of the solder joint 9 from its first position ( Fig. 6a ) in the direction of its second position ( 6C ), so a pending arc 10 is pressed into the chamber 11 in the housing 12. In addition, the plasma 14 is first pressed into the chamber 11, wherein, however, a portion of the plasma 14 - opposite to the direction of movement of the separating element 5 - also flows into the channel 22 in the separating element 5. By means of an outlet opening 23 formed in the insulating separating element 5 on the side facing away from the chamber 11, the plasma 14 can flow out of the channel 22 into the housing 12. By means of a second outlet opening 24 formed in the housing 12, which is formed on the side of the housing 12 opposite the first outlet opening 15, plasma 14 can then escape from the housing 12 in the direction opposite to the direction of movement of the separating element 5.

In the further embodiment according to Fig. 7 is in the insulating separator 5, a channel 25 is formed, which acts as a chamber in which a pending in the separation of the solder joint 9 arc 10 can be brought is. On the side of the separating element 5 facing the first terminal 6 of the varistor 3, the channel 25 is open, so that the separating element 5 is pushed with its channel 25 open on one side over the first end 8 of the conductive connecting element 4, when the separating element 5 leaves its first position ( Fig. 7a ) into its second position ( Fig. 7c ) emotional. The connecting element 4 is then separated from the first terminal 6 of the varistor 3 by the lower wall defining the channel 25. In this embodiment variant, a part of the electrically conductive connecting element 4, in particular its first end 8, is thus enclosed by the insulating separating element 5 when the separating element 5 is in its second position. Here, too, an arc 10 arising during the separation of the solder joint 9 is brought through the separating element 5 into the chamber 11 formed by the channel 25, which initially leads to an increase in the length of the arc 10.

How out Fig. 7 Moreover, it can be seen that on the side of the first terminal 6 of the varistor 3, on which in the normal state of the overvoltage protection element 1, the insulating separator 5 is not located, a closure member 26 is provided, on which the insulating separator 5 in its second position with the open Side of the channel 25 is applied. In the second position of the separating element 5, the channel 25, which is open on one side, is then sealed by the closure element 26, as a result of which a possibly still occurring arc 10 is "constricted" or "cut off" so that the arc 10 is extinguished at the latest. The closure element 26 has a through opening 27, through which the connecting element 4 is performed, so that the closure element 26 also serves as a holder for the connecting element 4.

The Fig. 8 and 9 show a further embodiment of an overvoltage protection element 1 according to the invention, wherein the insulating separating element 5 has two channels 25, 25 ', which run parallel to each other. The two channels 25, 25 'are open on the first terminal 6 of the varistor 3 side facing, so that in the second position of the insulating separator 5, the first end 8 of the connecting element 4 in the first channel 25 and the first terminal 6 of the varistor 3 are arranged in the second channel 25 'in the separating element 5. In contrast to the embodiment according to Fig. 7 . wherein the first terminal 6 of the varistor 3 is formed flat on one side of the varistor 3, stands in the overvoltage protection element 1 according to the Fig. 8 and 9 the first terminal 6 substantially perpendicular from the varistor 3. In order that the insulating separating element 5 can be displaced relative to the protruding first terminal 6, the second channel 25 'in its underside, which faces the varistor 3, has a slot extending in the direction of movement of the separating element 5, in which the terminal 6 moves of the separating element 5 can slide from the first position to its second position.

In addition to the closure element 26 for the first channel 25, a second closure element 28 is provided as termination for the second channel 25 'in the second position of the separating element 5. In the second position of the separating element 5, the two channels 25, 25 'are thus closed or sealed by the two closing elements 26, 28. In addition, in the open side of the second channel 25 'opposite rear wall 29 of the insulating separator 5, an outlet opening 30 is formed, through the plasma 14 controlled from the channel 25' can flow out.

The Fig. 10 and 11 show a variant of the previously described and in the Fig. 8 and 9 illustrated embodiment of the overvoltage protection element 1 according to the invention, in which the first terminal 6 protrudes substantially perpendicularly from the varistor 3 and the insulating separator 5 also has two channels 25, 25 'which are parallel to each other. In this embodiment, the first terminal 6 of the varistor 3 in the first position of the insulating separator 5 is partially enclosed by the second channel 25 'as shown Fig. 11a is apparent. For this purpose, the second channel 25 'has a greater length than the first channel 25, which is open on the side facing the terminal 6 of the varistor 3. In the first position of the insulating separating element 5, the first channel 25 is thus located to the left of the first end 8 of the connecting element 4.

In the second position of the insulating separator 5 according to FIG Fig. 11c is then the first end 8 of the connecting element 4 in the first channel 25 while the first terminal 6 of the varistor 3 in the second channel 25 'is arranged. The two channels 25, 25 'are of a longitudinal wall of the first channel 25 and an additional wall 31 separated from each other, wherein the additional wall 31 as well as the first terminal 6 of the varistor substantially vertically from the varistor 3 and the housing 2 which surrounds the varistor 3, projects.

In this embodiment, since the second channel 25 'has a second rear wall 32, only one shutter member 26 is provided as the termination for the first channel 25 in the second position of the partition member 5. In the second position of the separating element 5 are thus also two channels 25, 25 'closed or sealed. In addition, in the rear wall 29 of the second channel 25 ', which is spaced in the first position of the insulating separator 5 from the first terminal 6 of the overvoltage limiting device 3, an outlet opening 30 is formed through which plasma 14 controlled from the channel 25' can flow out ,

In Fig. 12 a further embodiment of an overvoltage protection element 1 according to the invention is shown, which is a variant of the in Fig. 6 illustrated embodiment is. Also in this embodiment, a channel 22 is formed in the insulating separator 5, which is open on the first terminal 6 of the varistor 3 side facing. On the other side of the housing 12, a partition wall 33 is formed in the housing 12, so that the chamber 11 is divided into two sub-chambers 11 ', 11''The partition wall 33 is slightly thinner than the channel 22 in the insulating partition member 5, so that the Partition 33 slides into the channel 22 as the insulating partition 5 moves from its first position to its second position.

Is the insulating separator 5 after the separation of the solder joint 9 from its first position ( Fig. 12a ) in the direction of its second position ( Fig. 12c In this case, a pending arc 10 and the plasma 14 are pressed into the two sub-chambers 11 ', 11 "in the housing 12. In addition, the arc 10 and a part of the plasma 14 are also opposite to the direction of movement of the separating element 5 in the Channel 22 is pressed in the separator 5, resulting in a large extension of the arc 10. By formed in the housing 12 outlet openings 15, which formed on the insulating separator 5 opposite side of the housing 12 can plasma 14 escape in the direction of movement of the separating element 5 from the housing 12.

Fig. 13 finally shows another variant of in Fig. 6 In this embodiment, two insulating separating elements 5, 5 'are arranged in the housing 12, which are in the normal state of the varistor 3 on different sides of the first terminal 6 of the varistor 3, that is, the separator 5 is on the left Side and the separating element 5 'arranged on the right side of the terminal 6. In the first, left partition member 5, two channels 22, 22 'are formed, which are separated by a partition 34 from each other. In the second, right dividing element 5 ', three channels 22, 22', 22 "are formed, which are separated from one another by two dividing walls 34, 34 ', the channels and dividing walls in the two dividing elements 5, 5' being arranged relative to each other. that the two insulating separating elements 5, 5 'engage in one another like a comb when the two separating elements 5, 5' each move from their first position to their second position, whereby an arc 10 present after the separation of the soldered connection 9 is meandered into the individual channels 22 , 22 ', 22 ", resulting in a large increase in the length of the arc 10. At the same time, the plasma 14 is pressed into the individual channels 22, 22 ', 22 "in the two insulating separating elements 5, 5'.

Via the outlet openings 23 formed in the separating elements 5, 5 ', the plasma 14 can flow out of the channels 22, 22', 22 "in the separating elements 5, 5 'in both directions into the housing 12. In addition, outlet openings are formed on both end faces of the housing 12 15, 24 also allow a controlled escape of the plasma 14 from the housing 12th

Claims (19)

Overvoltage protection element (1) with a housing (2), with a in the housing (2) arranged overvoltage limiting component (3), in particular a varistor, with an electrically conductive connecting element (4) and with at least one insulating separating element (5),
wherein the overvoltage limiting component (3) has a first terminal (6) and a second terminal (7),
wherein the insulating separator (5) is movably disposed relative to the first terminal (6) of the overvoltage limiting device (3) so as to be movable from a first position to a second position,
wherein, in the normal state of the overvoltage protection element (1), a first end (8) of the electrically conductive connection element (4) is electrically conductively connected to the first connection (6) of the overvoltage limiting component (3) and the insulating separation element (5) is held in its first position is and
wherein upon reaching a critical state of the overvoltage limiting component (3) the connection between the first end (8) of the electrically conductive connecting element (4) and the first terminal (6) of the overvoltage limiting component (3) separates and the insulating separating element (5) a force is moved to its second position, in which a section of the separating element (5) is arranged between the first end (8) of the electrically conductive connecting element (4) and the first terminal (6) of the overvoltage limiting component (3),
characterized,
in that the at least one insulating separating element (5) is designed in such a way that an electric arc (10) produced when the connection between the first end (8) of the electrically conductive connecting element (4) and the first terminal (6) of the overvoltage limiting component (3) is severed ) is placed in at least one partially closed chamber (11). Overvoltage protection element (1) according to claim 1, characterized in that in the normal state of the overvoltage protection element (1), the first End (8) of the electrically conductive connecting element (4) via a thermally disconnecting compound (9) with the first terminal (6) of the overvoltage limiting component (3) is electrically connected, wherein the thermally disconnecting compound (9) when a limit temperature of overvoltage limiting component (3) separates. Overvoltage protection element (1) according to claim 1 or 2, characterized in that the insulating separating element (5) is movably arranged in a housing (12) whose volume is greater than the volume of the separating element (5) that the housing (12) a Opening (13) through which in the normal state of the overvoltage protection element (1) the first end (8) of the electrically conductive connecting element (4) to the first terminal (6) of the surge arrester (3) is electrically connected, and that the chamber ( 11) is formed by the region of the housing (12) in which the insulating separating element (5) is not arranged in the normal state of the overvoltage protection element (1). Overvoltage protection element (1) according to claim 3, characterized in that the housing (12) in the region of the chamber (11) has an outlet opening (15). Overvoltage protection element (1) according to one of Claims 1 to 4, characterized in that the insulating separating element (5) has an opening (17) through which the first end (9) of the electrically conductive connecting element (4) is in the normal state of the overvoltage protection element (1) ) is electrically connected to the first terminal (6) of the surge arrester (3). Overvoltage protection element (1) according to one of claims 1 to 5, characterized in that in the insulating separating element (5) at least one channel (22) is formed, which is open on the chamber (11) facing side. Overvoltage protection element (1) according to claim 6, characterized in that within the housing (12) at least one web or a partition wall (33) is formed, extending in the direction of movement of the insulating Separating element (5) extends, so that through the web or the partition (33), the chamber (11) in the housing (12) in at least two sub-chambers (11 ', 11 ") is divided. Overvoltage protection element (1) according to claim 6 or 7, characterized in that the insulating separating element (5) has at least one outlet opening (23) via which the channel (22) is connected to the interior of the housing (12), wherein the housing ( 12) preferably has at least one outlet opening (24). Overvoltage protection element (1) according to claim 8, characterized in that the outlet opening (23) is formed in the insulating separating element (5) on the side facing away from the chamber (11) and the outlet opening (24) in the housing (12) of the outlet opening (23). in the separating element (5) opposite. Overvoltage protection element (1) according to one of Claims 6 to 8, characterized in that an outlet channel in the housing (12) extends between the outlet opening (23) in the insulating separating element (5) and the outlet opening (24) in the housing (12) the outlet channel is preferably a medium for cooling and / or damping of the outflowing plasma (14) is arranged. Overvoltage protection element (1) according to one of claims 3 to 10, characterized in that the housing (12) and / or the insulating separating element (5) consists at least in sections of a gaseous material. Overvoltage protection element (1) according to one of claims 3 to 11, characterized in that the housing (12) and / or the insulating separating element (5) consists of a mechanically and thermally stable material. Overvoltage protection element (1) according to one of Claims 3 to 12, with a plurality of insulating separating elements (5, 5 '), characterized in that each separating element (5, 5') is arranged movably in a housing (12, 12 '), each one being arranged Housing (12, 12 ') has an opening (13, 13') and the openings (13, 13 ') are arranged to each other, that in the normal state of the overvoltage protection element (1), the first end (8) of the electrically conductive connection element (4) is electrically conductively connected to the first connection (6) of the overvoltage limiting component (3) through the openings (13, 13 '). Overvoltage protection element (1) according to claim 13, characterized in that in the normal state of the overvoltage protection element (1) at least two insulating separating elements (5, 5 ') are arranged substantially on different sides of the first terminal (6) of the overvoltage limiting component (3) the directions of movement of these separating elements (5, 5 ') are opposite to each other. Overvoltage protection element (1) according to claim 1 or 2, characterized in that at least one channel (25) is formed in the insulating separating element (5) as a chamber (11) into which an emerging arc (10) can be moved The first end (8) of the electrically conductive connecting element (4) in the second position of the insulating separating element (5) in the channel (25) in the separating element (5) is arranged. Overvoltage protection element (1) according to claim 15, characterized in that on the side of the first terminal (6) of the overvoltage limiting component (3) on which in the normal state of the overvoltage protection element (1) the insulating separating element (5) is not located, a closure element ( 26) is arranged, on which the insulating separating element (5) rests in its second position with the open side of the channel (25). Overvoltage protection element (1) according to Claim 15 or 16, with a first terminal (6) projecting from the overvoltage limiting component (3), characterized in that a second channel (25 ') is formed in the insulating separating element (5), which is parallel to the first Channel (25) extends, and that in the second position of the insulating separating element (5), the first end (8) of the electrically conductive connecting element (4) in the first Channel (25) and the terminal (6) of the overvoltage limiting component (3) in the second channel (25 ') are arranged. Overvoltage protection element (1) according to claim 17, characterized in that the first channel (25) and / or the second channel (25 ') in the second position of the insulating separating element (5) bears against a closure element (26, 28). Overvoltage protection element (1) according to claim 17 or 18, characterized in that in at least one wall of the insulating separating element (5) an outlet opening (30) is formed, preferably in the rear wall (29) of the second channel (25 '), in the first position of the insulating separator (5) from the first terminal (6) of the overvoltage limiting device (3) is spaced.

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