EP3673497B1 - Disconnecting device for a surge arrester - Google Patents

Description

The invention relates to a surge arrester with a disconnecting device.

From the EP 2 011 128 B1 a disconnection device for a surge arrester is previously known. In this disconnecting device, the switching movement is carried out by a switching tongue, which is aligned via a permanently acting spring force in the opposite direction to the holding force produced by a protective solder. The permanent pre-tensioning force acting indirectly on the switching tongue or its soldering point to generate a desoldering or switching force via a separating block is supported by at least one further, independently acting pre-tensioning force and a supplementary switching force with the same effective direction.

The distribution of forces is such that in the resting state a small resultant force acts on the soldering point and the greatest possible resultant force executes the switching movement during the desoldering process by creating the pretensioning force in the desoldering phase through the formation of the switching tongue from a memory or bimetallic strip or a Switching tongue made of a spring material, which has an expression with overbend web, provided and the supplementary switching force is formed after the end of the soldering process by shifting a force transmission point of the resulting pretensioning lever force on the switching tongue.

The displacement of the force transmission point is derived from a rotary movement and in this respect the separating block has a pivot bearing.

The switching movement of the previously known switching tongue results from a spring tension which, indirectly via the separating block, exerts a pretension on the switching tongue and thus the solder contact point. As a result of the rotary movement of the disconnecting block, the disconnected switching tongue executes a rapid switching movement over a large opening path and thus creates a reliable separation between the arrester element and the line routing formed by the switching tongue. At the same time, the rotary movement carried out by the separating block is displayed at its end position in a viewing window, so that the switching position of the separating block can be recognized as the triggered state on the outside by means of a viewing surface.

The soldering point that connects the switch tongue to the diverter element is designed and manufactured in such a way that the separation takes place safely and at a point in time at which no thermal damage is to be expected from an overheated diverter element. This point is initially determined by the choice of the perpendicular, with the mechanical pretensioning also providing an essential part of this.

Follow the switch tongue EP 2 011 128 B1 Several bending and thus deformation sections are provided, which lead to an undesirable increase in current density. For this reason, the known solution is not suitable for safely absorbing or carrying high surge currents and high short-circuit currents.

In the case of the overvoltage protection element DE 20 2014 103 262 U1 , which is intended for use between a neutral conductor and a potential equalization in the power supply of a low-voltage network, the same has a housing and an overvoltage-limiting component arranged in the housing with two connection contacts for the electrical connection of a current path to be protected.

Furthermore, there is an electrically conductive connecting element as well as an insulating separating element and at least one spring element.

A gas-filled surge arrester is used as the surge-limiting component, the insulating separating element being arranged displaceably on the housing and being able to be moved from a first position to a second position by the force of the at least one spring element.

In the normal state of the overvoltage protection element, the second end of an electrically conductive connecting element is electrically conductively connected to the second electrode of the surge arrester via a thermally separating connection and the insulating separating element is fixed in a first position.

When the overvoltage protection element exceeds a predetermined limit temperature, the thermal connection between the second end of the electrically conductive connection element and the second electrode of the surge arrester is broken and the insulating separating element is moved into its second position by the force of the spring element, in which a section of the separating element is located between the second end of the electrically conductive connecting element and the second electrode of the overvoltage element.

The electrically conductive connecting element is designed as an angled metallic strip and therefore basically has a high current carrying capacity. For the purpose of making contact between the conductive connecting element and the second connection contact, the aforementioned angled portion is present, which forms a contact surface that can be connected to the connection contact. In this regard, too, a current constriction is formed in the kink area. Another disadvantage is the straight-line displacement of the insulating separating element with the risk of tilting in the slide guide provided, in particular when the surge arrester has already been subjected to thermal stress.

From the US 2016/0134104 A1 a disconnection device for an overvoltage conductor is known in which an angled metallic strip is connected with one end to a conductor element via a thermal separation point, and a non-electrically conductive separation element is additionally provided. The separating element can be moved from a first to a second position by means of a spring, the movement being prevented by a blocking element connected to the metallic strip. If an overvoltage occurs, which leads to the loosening of the thermal separation point, the metallic strip becomes detached from the diverter element, so that the blocking element no longer prevents the separation element from moving. In the second position the separating element isolates the end of the metallic strip from the diverter element.

From the above, it is the object of the invention to provide a further developed surge arrester with a disconnecting device, which is constructed in a particularly simple manner and thus inexpensive to manufacture and which is able to handle extremely high surge currents or short-circuit currents in relation to a switching tongue carrying surge current or short-circuit current respectively.

The object of the invention is achieved by a surge arrester with a disconnecting device according to the combination of features of claim 1, the subclaims representing at least useful embodiments and developments.

The surge arrester with a disconnecting device, which is received by a support body, and with plug contacts extending from the support body to the external connection, which are connected to at least one arrester element of the surge arrester, has a switching tongue which is connected to the at a first end via a thermal separation point Conductor element and is connected with a second end to one of the plug contacts.

Furthermore, the separating device comprises an insulating separating block which is pivotably mounted on the support body and is spring pretensioned, the spring preloading acting on the thermal separation point via the switching tongue.

The support body, which accommodates both the diverter element and the actual separating device, is an injection-molded plastic part that is surrounded by a separate outer housing. The overall arrangement formed in this way can be implemented as a plug-in part and thus as an exchangeable surge arrester that can be introduced into a conventional lower part with connection terminals.

Irrespective of this, the disconnection device according to the invention that is presented is also suitable for other types of surge arrester with support bodies.

According to the invention, the switching tongue is designed as a straight, elongated, metallic, resiliently elastic separating strip with a rectangular cross section.

The cross-sectional area is implemented in such a way that a design for maximum surge currents or maximum short-circuit currents is easily possible.

The connection to a contact surface of the diverter element takes place by means of a thermal separation point known per se, for example by means of a solder connection.

According to the invention, however, the actual thermal separation point is implemented over the broad side of a first separation strip end.

The connection to one of the plug contacts, on the other hand, takes place via the circumference of a second separating strip end, which dips into a slot-shaped recess within a section of the plug contact facing the support body.

In this regard, the recess is essentially complementary to the cross-sectional area of the second separating strip end.

The second end of the separating strip is therefore inserted into the recess with a rectangular cross-section and fixed there, for example, in a materially bonded manner.

When the melting point of the thermal separation point is reached, the separating block is subject to a position shift due to the spring preload.

As a result, the separating strip is lifted from the contact point with its first separating strip end. The separating block then enters the resulting space and leads to a safe separation.

The creation of a possible electric arc is reliably avoided or suppressed from the start.

The separating block itself is designed as a rotary lever. The axis of rotation is located here at one end that is opposite the point of attack for generating the spring preload, with the result of a corresponding force amplification on the position of the thermal separation point between the axis of rotation and the point of application for the spring preload.

The shift in position of the separating block can be seen through a viewing window in an outer housing surrounding the support body, so that the current state of the surge arrester can be traced.

In one embodiment of the invention, a guide attachment for receiving the second separating strip end is formed on the support body.

In one embodiment of the invention, the second end of the separating strip is soldered or welded to the plug contact.

Again, the separating block is designed as a rotary slide valve and is provided with a flattened area in the form of a simple inclined surface or a wedge surface on its edge pointing towards the thermal separation point. This results in a quick and reliable separation of the contact surfaces connected by solder using the elasticity of the switching tongue, which is designed as a separation strip. The separation strip is only in its elastic area during the separation movement claimed. Plastic deformations neither occur nor are they necessary for the production side.

The lever-reinforced forces acting on the thermal separation point can overcome blockages caused by solder residue or rough material surfaces or other unevenness during the melting process.

The invention is to be explained in more detail below using an exemplary embodiment and with the aid of figures.

• Fig. 1 eine perspektivische Ansicht eines Steckteiles eines Überspannungsableiters ohne Außengehäuse und ohne Unterteil, jedoch mit äußeren elektrischen Schraubanschlussklemmen im funktionsbereiten, das heißt nicht abgetrennten Zustand;
• Fig. 2 eine Darstellung ähnlich derjenigen nach Fig. 1, jedoch im abgetrennten Zustand, wobei sich hier der Abtrennbock bereits positionsverlagert hat und in den Zwischenraum zwischen Kontaktstelle und Abtrennstreifen eingetaucht ist;
• Fig. 3 eine Detailansicht zur Ausbildung der Verbindung eines der Steckkontakte über den Umfang eines zweiten Abtrennstreifenendes, welches in eine schlitzförmige Ausnehmung innerhalb eines zum Tragkörper weisenden Abschnittes des Steckkontaktes eintaucht.

Here show:

• Fig. 1 a perspective view of a plug-in part of a surge arrester without an outer housing and without a lower part, but with external electrical screw connection terminals in the operationally ready, that is, not disconnected state;
• Fig. 2 a representation similar to that after Fig. 1 , but in the separated state, the separating block has already shifted in position and is immersed in the space between the contact point and the separating strip;
• Fig. 3 a detailed view of the formation of the connection of one of the plug contacts over the circumference of a second separating strip end, which dips into a slot-shaped recess within a section of the plug contact facing the support body.

The disconnection device according to the exemplary embodiment can be part of a surge arrester in the form of a plug-in part, as shown in FIG Figure 1 and 2 is indicated.

The plug-in part shown here does not yet have an outer housing in order to make the structure and function of the separating device clear.

The plug-in part has a support body 1, which has a chamber-like recess on one side, which has at least one diverter element.

The support body has an opening 2 which allows access to a contact point 3 of the arrester element.

The thermal separation point known per se is implemented in this area.

Furthermore, the support body 1 has a curved guide 4 for receiving a spring 5 which generates a pretensioning force. It should also be noted that the spring 5 is supported at one end on a stop of an insulating separating block 6 designed as a rotary slide valve.

The rotary slide valve sits on an axis of rotation 7, which can be designed as an extension and thus an integral element of the support body 1.

External connections of the surge arrester are provided as plug contacts 8; 9 executable, which engage in U-shaped counter contacts 10 and 11.

The mating contacts 10 and 11 are connected to external screw terminals 12 and 13 known per se or are part of them.

According to the invention, the switching tongue of the thermal separation point is designed as a straight, elongated, metallic, resiliently elastic separation strip 14.

The connection to the contact surface 3 of the diverter element takes place, as explained, by means of the thermal separation point, specifically via the broad side of a first separation strip end 140.

The connection to one of the plug contacts 9, on the other hand, takes place via the circumference of a second separating strip end 141, which dips into a slot-shaped recess 15 in an extension section 16 of the plug contact 9.

The recess 15 here essentially corresponds to the cross-sectional area of the second separating strip end 141 and is designed to be complementary to this end.

A corresponding detailed representation is the Figure 3 removable.

When the melting point of the thermal separation point is reached, the separating block 6 is subject to a position shift; this is in the Figures 1 and 2 traceable by moving to the left.

Here, the separating strip lifts off the contact point 3 with its first separating strip end 140. Furthermore, the separating block 6 enters the resulting space with its area 60 (see FIG Figure 2 ).

The shift in position of the separating block 6 can be seen through a viewing window (not shown in the figures) in an outer housing (not shown) that encloses the support body 1.

In this regard, a display surface 61 is formed on the separating block 6.

The separating block 6 is, as from the Figures 1 and 2 understandable, designed as a rotary valve. At its edge 62 pointing towards the thermal separation point, the separating block 6 can have a flattening in the form of an inclined surface or a wedge surface in order to optimize the penetration into the separation point area and the separation process.

Claims (6)

1. A surge arrester comprising a disconnecting device which is received by a support body (1), and plug contacts (8; 9) which extend from the support body (1) and are connected to at least one arrester element of the surge arrester,
   further comprising a switching tongue (14) which is connected at a first end (140) to the arrester element via a thermal disconnection point and by a second end (141) to one of the plug contacts (9),
   an insulating disconnection bracket (6) which is swivel-mounted at the support body (1) and is spring-preloaded,
   the spring preload acting on the thermal disconnection point by means of the switching tongue (14),
   the switching tongue further being configured as a straight-surfaced, elongated, metallic, resiliently elastic disconnection strip (14) having a rectangular cross section,
   the connection to a contact surface (3) of the arrester element being effected by means of the thermal disconnection point via the broadside of a first disconnection strip end (140), and
   when the melting point of the thermal disconnection point is reached, the disconnection bracket (6) being subjected to a shift in position and, in so doing, lifting the disconnection strip (14) off the contact point (3) by its first disconnection strip end (140), and the disconnection bracket (6) entering the resulting intermediate space, characterized in that
   the connection of the switching tongue (14) to one of the plug contacts (9) is made by means of the circumference of the second disconnection strip end (141),
   which plunges into a slot-shaped recess (15) within a portion (16) of the plug contact (9) facing the support body (1), the recess (15) being substantially complementary to the cross-sectional area of the second disconnection strip end (141).
2. The surge arrester according to claim 1, characterized in that the disconnection bracket (6) is in the form of a rotary lever.
3. The surge arrester according to claim 1 or 2, characterized in that the shift in position of the disconnection bracket (6) is visible through an inspection window in an outer housing enclosing the support body (1).
4. The surge arrester according to any of the preceding claims, characterized in that a guide projection (100) for receiving the second disconnection strip end (141) is integrally molded with the support body (1).
5. The surge arrester according to any of the preceding claims, characterized in that the second disconnection strip end (141) is soldered or welded to the plug contact (9).
6. The surge arrester according to any of the preceding claims, characterized in that the disconnection bracket (6) is in the form of a rotary slide and has a flattened portion in the form of a simple sloping surface or wedge surface on its edge (62) facing the thermal disconnection point.

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