RU2407087C2 - Discharge arrester for overvoltage protection, comprising at least one discharge element, for instance varistor - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: discharge arrester for overvoltage protection comprises at least one discharge element, for instance varistor, and disconnection device, comprising soldered joint (11), which inside overvoltage protection discharge arrester is related to electric circuit of connection. Via the soldered joint (11), the movable conducting section (12) or movable conducting bridge (22) is connected to discharge element at one side, and at the other side, this conducting section (12) or this bridge (22) is connected to electric external connection of discharge arrester. Disconnection device comprises spring (15), creating a force of pretension, besides, corresponding vector of force directly or indirectly influences conducting section (12) or bridge (22) in direction of disconnection. Thermally connected stop element (17) blocks movable conducting section (12) or movable conducting bridge (22) relative to vector of pretension force, and therefore soldered joint (11) of disconnection device is not exposed to continuous power load. ^ EFFECT: increased reliability of disconnection with small electric arc in case of malfunction and increased stability of actuation for a long period of time. ^ 15 cl, 4 dwg

Description

Technical field

The invention relates to a surge arrester (hereinafter referred to as a surge arrester) comprising at least one discharge element, for example a varistor, as well as a disconnecting device, so that the discharge element or discharge elements are disconnected from one network or all poles from the network, the disconnecting device comprises a junction, which inside the arrester is connected to the electrical connection circuit, and through the junction, the movable conductive section or movable conductive bridge is connected to the discharge element with one ones, and the conductive portion or bridge on the other side is connected to an electrical external connection of the arrester. Further, the disconnecting device comprises a spring generating a pre-tension force, the corresponding force vector acting indirectly or directly on the conductive portion or bridge in the direction of separation according to the preamble of claim 1.

State of the art

The arresters, also of the plug-in design, have for many years been related to the prior art. In the case of plug-in arresters, there is a lower part with contact sockets and an upper part with contact pins adapted to be inserted into the contact sockets, as well as with a surge element located between these contact pins, preferably a varistor.

In the lead wire to the discharge element, a junction is located as a thermal fuse, in which one of the soldered parts of the lead wire is connected to a spring, which pre-pulls this lead wire assembly away from the junction.

This part of the lead wire can be made in the form of a flexible cable-like conductor, and here problems arise in the case of high shock currents.

Due to the problems associated with shock currents, according to EP 0905839 B1, it was proposed to connect a pre-tensioned part of the supply wire using a bridge, while both ends are connected via junctions to other parts of the supply wire. That part of the lead wire, which is movable, has, in itself, rigid properties and can be made with a relatively large cross-section of a well-conducting material. This creates a high resistance to shock current. Due to the two interruption points provided, a particularly reliable disconnection of the arrester from the network must be achieved.

In developing this solution according to EP 0905839 B1, it was proposed that the bridge in the cross section be in the form of a double letter L. Thus, both sections of the lead wire connected by the bridge can be located relatively far from each other. According to EP 0905839 B1, a solution is also known consisting in supplying a bridge at one end with a jumper on which a spring is created, which creates a preliminary tension.

In addition, it is possible to provide an optical fault indication in the plug arresters according to EP 0905839 B1, the fault indication comprising an opening located at the end of the upper part, as well as a lever movably resting inside the upper part and extending from the opening to the path of the conductive bridge, moreover the first lever end located in the opening region carries a signal plate. The signal plate contains a marking typical of the corresponding operating state on its surface facing the opening. This marking can be transferred using the bridge during its opening movement, taking into account the existing lever, from a position invisible due to the opening to a visible position.

A junction that holds the bridge under tension contains solder with a specific melting point. The melting point is chosen in such a way that it is not achieved at thermal energies, which the spark gap can take without harming itself. Thus, the solder joint remains active until the arrester is damaged, but ceases to operate at higher values of thermal energy.

Taking into account the maximum operating temperature that meets the standards, relatively low-melting solders should be used inside such arresters. However, such solders are limited in their ability to accept mechanical forces, especially shear forces.

The latter means, in turn, that the spring pretension force that acts on the bridge and the corresponding junction must be limited. However, the limited spring force is not beneficial for the quick disconnecting movement of the rigid part of the bridge, especially when, due to the eutectic behavior of the solder, there is no immediate penetration of the junction.

Disclosure of invention

It follows from the foregoing that the object of the present invention is to provide an improved arrester, especially with a thermal disconnect device, which shows a very reliable disconnect characteristic with a small electric arc in the event of a malfunction and has high long-term stability, especially with respect to the solder joint of the thermal disconnect section.

The objective of the invention is solved with the help of a spark gap in its definition according to a combination of features according to claim 1, moreover, the dependent claims are at least reasonable options for implementing and developing the invention.

Accordingly, the main idea of the invention lies in the fact that the thermally switched locking element additionally blocks the movable conductive portion or the movable conductive bridge provided relative to the continuously acting vector of the pre-tension force. Thus, the junction of the disconnecting device is not subject to continuous power load.

Thanks to this additional part, such as a molded part, a latch is created that unlocks only when the adjustable melting point is reached, and thus the pre-tensioned spring then activates the disconnecting device.

The sensitive junction of the electrical disconnecting device is subject to a spring force or spring preload force intermittently. Thanks to this, it now becomes possible to correct and optimize the calculation of mechanical components, that is, the spring, the disconnecting lever and the ratios of the levers.

According to the invention, it is especially possible to make large spring forces effective, which realize rapid movement during the actual separation. Under these conditions, the breaking capacity is significantly improved in case of activation.

In one embodiment of the invention, a thermally switched shut-off element, on the one hand, enters the effective region of the conductive section, and on the other hand, rests on the arrester housing or on the separation wall of the arrester and contacts the arrester in a thermal, heat-conducting manner.

In another embodiment of the invention, a thermally-activated locking element in the form of a finger-shaped part blocks the path of movement of the linkage, which is located between the spring and the conductive section.

A thermally switched locking element in the form of a preformed assembly may consist of a low melting solder or be made in a similar manner.

The solder properties for the thermally switched locking element can be selected independently of the electrical parameters, taking into account only the mechanical aspect, for example, high resistance to tensile force.

The movable conductive portion may be in the form of a spring tongue, and thus there is additional support for the disconnection movement in the event of a malfunction.

The linkage may be coupled to an optical failure indication to signal a failure condition or a failure state of the discharge element.

Of course, it is possible to activate the communication contact by acting on the linkage or on the movement of the conductive portion.

In one embodiment of the invention, the movable conductive element is a stamped bent part that has an external connection, made especially in the form of a plug contact. Thus, this part can be economically manufactured and easily mounted without high costs.

In a preferred embodiment, the activation temperature of the closure element is lower than the melting temperature of the junction. Thus, the action of the function of the locking element stops when the temperature rises to a critical region, and thus, with a further increase in temperature in the event of a malfunction, the disconnection movement can work or can occur unhindered.

If, for example, in the case of a lever transmission, it is ensured that when the activation temperature of the locking element is reached, the lever assembly passes back the first path in order to abut the conducting section or the bridge, then this backward path can be used to activate the communication contact or optical an indicator that signals that a critical increase in temperature has occurred, in order to thus show that it is advisable to replace the arrester.

Compared to current thermal disconnecting devices, the pre-tension force, which is preferably generated by the arrangement of the springs, can take a higher value than the possible long-term load of the junction, so that in the event of a malfunction, the desired very fast movement of the separation of the conductive section or the conductive bridge is guaranteed.

Brief Description of the Drawings

The invention is further explained in more detail using an example of an embodiment and with the help of the drawings.

They show the following.

Figure 1: the first example proposed by the invention of the solution with a brazed shaped part, which is located in the disconnect bracket in thermal contact with the varistor plate.

Figure 2: an implementation option in which the soldered shaped part of the locking element is located directly on the conductive section and has an auxiliary support in the dividing wall of the housing.

Figures 3 and 4: a third embodiment of the invention with a two-stage indication of load and fault.

The implementation of the invention

In the cases presented in figures 1 and 2, come from a plug-in arrester with the main part. This main part 1 contains a rear recess with means for attaching 2 carrier tires.

In the free space made by both knees of the U-shaped main part 1, the arrester 3 itself is inserted. The corresponding plug contacts 4 on the arrester 3 enter the contact recesses 5 in the main part 1. The encoding 6 in the main part 1, on the one hand, and the response Arrester 3, on the other hand, prevents the installation of incorrect or unsuitable arrester.

Arrester 3 contains inside itself an arrester, not shown actually, for example a varistor plate.

The varistor plate located behind the partition wall 7 contains two connections. The first connection 8 is connected to the left-hand pin 4 through a conductive part 9.

The second connection 10 is carried out through the dividing wall 7 and there is connected through a junction 11 with a movable conductive section 12.

The movable conductive portion 12 passes into the plug 4 located on the right side.

A lever-like disconnect bracket 13 comprises an optical failure indication 14 on the upper side.

The first end of the spring 15 enters next to the optical failure indication 14, the second end of the spring 15 being fixed in the area of the dividing wall 7. Thus, the spring 15 is the cause of the force acting through the disconnecting bracket 13 and the pusher 16 on the movable conductive section 12 and thereby on sleep 11.

A thermally activated locking element 17, made, for example, in the form of a soldered shaped part, is located in the disconnecting bracket 13 and locks it finger-like through the corresponding auxiliary support in the dividing wall 7.

By means of a thermally activated locking element 17, the vector of the pre-tension force is blocked, and thus the junction 11 of the disconnecting device is not subject to a constant power load.

Arrester 3 also contains a housing 18 with a window 19 relative to the optical indication 14 of the malfunction. In the case of the embodiment of FIG. 2, it is based on a structure that is similar to the structure described in connection with FIG.

Of course, in this case, the thermally switched locking element 17 is not a locking finger in the disconnecting bracket, but is located in the area of the movable conductive section 12 and is indicated by pos. 20.

Also in this embodiment, the thermally switched locking element prevents the spring pre-tensioning force 15 from loading the junction 11 for a long time, followed by undesirable tensile or shearing forces. Only when the melting temperature of the brazed shaped part 20 is reached, the force disengages, and with a further increase in temperature after reaching the temperature relative to the junction 11, the disconnection process can occur in a known manner.

As can be seen from figures 1 and 2, the movable conductive section 12 can be made entirely with right-hand plug contact 4 in the form of a stamped bent part and used to facilitate installation.

Figures 3 and 4 show a third embodiment of the invention with a two-stage indication of load and fault.

Figure 3 represents the state in which there has not yet been any critical thermal loads for the arrester and in which the locking element 17 has not yet worked.

4, on the contrary, shows the state after the actuation of the locking element 17.

In the form shown in FIGS. 3 and 4, the locking element 17 is an integral part of the two-stage indication of the load and the failure, and there is a pivotally connected lever arm 28, the end of which 29 is included in the locking valve 24. This locking valve 24 is in mechanical contact with the stop 27 of the node 23 bridge control and locks this node 23 bridge control in the state according to Fig.3.

The bridge control unit 23 is held by pre-tensioning the spring 15 and comprises a recess 26, which includes the protrusion 25 of the conductive bridge 22.

In the state of the blocked bridge control unit 23, due to the action of the gate valve 24, between the recess 26 and the protrusion 25, as shown in Fig. 3, fragment A, there is a gap. This means that the force of the spring 15 is not transferred to the critical solder joint, which is located between the bridge 22, the corresponding connection of the discharge element and the plug contact 4.

Thus, the locking element with its locking valve 24 receives the spring pretension of the bridge control unit 23 in the idle state and diverts the spring pretension force. In the actuated state, on the contrary, the gate valve 24 loses contact with the stop 27 of the bridge control unit 23, and, as a result, the gap disappears according to that shown in fragment A of FIG. 4. Only in this case, the action of the spring 15 is manifested to create a pre-tension force through the bridge control unit 23 in the direction of the bridge 22.

The lever arm 28 of the locking element 17 is held by the solder pin or solder finger 30 as the actual thermal locking element, the melting temperature of this solder pin or solder finger 30 may be lower than the temperature of the solder that connects the bridge 22 to the corresponding connection of the discharge element and to the plug contact four.

If, for example, a thermal load of the arrester has arisen, which has not yet led to a functional failure of the discharge element itself, but is important for future performance or for the frequency of replacement of the arrester, then under the influence of the spring 32, the lever arm 28 is shifted to the left in the position shown in FIG. 4, namely, together with a shutoff valve 24, which is connected to the optical indicator 14 of the malfunction. The optical fault indicator 14 then falls into the area of the window not shown and signals the onset of heat load.

As is clear from the figures 3 and 4, the end 29 of the lever arm enters the grooved ledge of the gate valve 24 in order to be able to capture the gate valve 24 from the side of movement.

By locking between the gate valve 24 and the abutment 27 of the bridge control unit 23, the pre-tension of the spring 15 can be selected to be very large, and there is no undesirable mechanical long-term load of the junction from the side of the bridge or several junctions therein. On the other hand, this high pre-tension of the spring 15 contributes to a very quick opening and thereby the disconnection of the discharge element in case of load. By positioning the solder pin or solder pin 30 directly on or in the dividing wall 7 and thereby in the immediate vicinity of the discharge element, the heat generated in this element in the event of a load is directly supplied to the solder pin or solder pin 30. Thus, control for reliable response characteristics of soldered material in the sense of the desired thermal response.

The bridge control unit 23 may be a tongue 33 for receiving the spring 15, which at the same time serves to guide the bridge control unit 23 by means of distance guiding elements 34.

To facilitate installation, especially the installation of the bridge control unit 23, wherein the bridge control unit 23 is under pre-tensioning of the spring 15, the bridge control unit 23 comprises openings 35 located on the branches. When a U-shaped bracket is inserted into the holes 35, regardless of the installation of other nodes, especially the locking element 17, the sealing of the bridge 22 is possible in a particularly simple way. Namely, in this case, the bracket, not shown in the drawings, due to the fact that it abuts against the outer edge of the dividing wall 7, blocks the movement of the bridge control unit 23. A solder pin or solder pin 30 may also be inserted into the holes 35 to realize the locking function.

Claims (15)

1. Surge arrester comprising at least one discharge element, such as a varistor, as well as a disconnecting device for disconnecting from the network a discharge element or discharge elements at one pole or at all poles, the disconnecting device comprising a junction that is inside a surge arrester for protection against overvoltage is connected to the electrical connection circuit, while through this junction the movable conductive section or movable conductive bridge is connected to the discharge element on one side, and with on the other hand, this conductive section or this bridge is connected to the electrical external connection of the arrester for surge protection, and in addition, the disconnecting device comprises a spring creating a pre-tension force, and the corresponding force vector acts indirectly or directly on the conductive section or bridge in the direction of separation characterized in that the thermally switched locking element blocks the movable conductive portion or the movable conductive bridge relates flax vector prestressing force, and thus junction isolation apparatus is not exposed to a continuous power load. 2. The arrester according to claim 1, characterized in that the thermally switched locking element on the one hand enters the effective region of the conductive section, and on the other hand rests on the arrester housing or on the separation wall of the arrester housing. 3. The arrester according to claim 1, characterized in that the thermally switched locking element in the form of a finger-shaped part blocks the path of movement of the linkage, which is located between the spring and the conductive section. 4. The arrester according to one of claims 1 to 3, characterized in that the thermally switched locking element is a pre-formed assembly of low-melting solder. 5. Arrester according to one of claims 1 to 3, characterized in that the movable conductive section is made in the form of a spring tongue. 6. The spark gap according to claim 3, characterized in that the linkage is connected to an optical indication of a malfunction. 7. Arrester according to one of claims 1 to 3, characterized in that the movable conductive section is a stamped bent part that contains a preformed external connection, especially a plug connection. 8. The arrester according to one of claims 1 to 3, characterized in that the activation temperature of the shut-off element is lower than the melting temperature of the junction. 9. The arrester according to one of claims 1 to 3, characterized in that the pre-tensioning force is larger in comparison with the possible long-term load of the junction, so that in the event of a malfunction, the desired very fast movement of separation of the conducting section or the conducting bridge is guaranteed. 10. The arrester according to one of claims 1 to 3, characterized in that the thermally switched locking element (17) is an integral part of the two-stage indication of the load or malfunction and contains a pivotally connected lever arm (28), the end (29) of which is included in the locking valve (25), which has mechanical contact with the stop (27) of the bridge control unit (23), and the bridge control unit (23) is held by pre-tensioning the spring and comprises a recess (26), which includes the protrusion (25) of the conductive bridge, and the locking element (17) with its lock with a latched valve (24), it takes up the pre-tension of the spring of the bridge control unit (23) in an unworked state and diverts them from the side of the force in such a way that there is a gap between the recess (26) and the protrusion (25), and in the activated state, on the contrary, (24) has no contact with the stop (27) of the bridge control unit. 11. Arrester according to claim 10, characterized in that the gate valve (24) is connected to the optical indication (14) of the malfunction. 12. Arrester according to claim 10, characterized in that the lever arm (28) is fixed with a solder pin or a solder pin (30) as a thermal locking element. 13. Arrester according to claim 12, characterized in that the melting point of the solder pin or solder pin (30) is lower than the melting temperature of the solder, which connects the bridge (22) with the corresponding connection of the discharge element and with the plug contact (4). 14. The arrester according to claim 10, characterized in that the bridge control unit (23) is connected to another optical indication (31) of the malfunction. 15. The arrester according to one of claims 11 to 13, characterized in that the bridge control unit (23) is connected to another optical indication (31) of the malfunction.

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