EP2089893B1 - Overcurrent protection unit for use in overvoltage protection devices having high rated voltages - Google Patents

Abstract

The invention relates to an overcurrent protection unit for use in overvoltage protection devices having higher rated voltages in combination with a mechanical trip for a display and fusible elements for overload protection. According to the invention, a series circuit has a plurality of fusible elements forming a geometrically prescribed mechanical and electrical combination. The series circuit comprises a mechanical and electrical parallel combination of fusible elements, wherein at least one of the fusible elements of the parallel combination comprises a striker as a mechanical trip.

Description

The invention relates to an overcurrent protection device for use in surge protection devices with high rated voltages in combination with a mechanical release for a display and fuses for overload protection according to the preamble of claim 1.

Overvoltage protection devices are used in electrical and information technology networks to protect equipment, consumers and end devices. Such overvoltage protection devices limit especially in transient overvoltage events, e.g. Lightning events, the voltage to uncritical values. In the case of overvoltage events, the limitation is made by the derivation of pulse currents in the cross-path and thus generally in parallel with load connections. As overvoltage protection elements, e.g. Spark gaps, varistors, gas arresters, non-linear resistors and their combinations used.

The need for overvoltage protection devices with higher rated voltages is limited. The effort to develop and manufacture a special geometry of overvoltage protection elements, in particular spark gaps, as well as corresponding ignition devices and housing parts for each rated voltage level is very high. In addition, the requirements for the protection and display devices of Hilfszündkreisen for arresters with higher rated voltages are very large. This applies in addition to the separation distances, i. the creepage distances and clearances, including the magnitude of the rated voltage and the switching capacity of the protective devices of Hilfszündkreises, ie the corresponding electrical circuit.

In addition to the protection function for the overvoltage protection elements, the response of a fuse is often used as a display criterion for the overload and the separation of the overvoltage protection element. For this purpose, the power interruption or the increased voltage drop across the fuse is evaluated. In addition to the optical display, the electrical Signal also used for audible indicators or the opening and closing of switches for remote indication.

From the DE 199 14 313 A1 is the hedge of a starting aid a spark gap previously known. In this case, fuses or reversible fuses are used. The melting of the fuse is used with the aid of electronic circuits for optical, acoustic and / or electronic display.

After the fuse has responded, the spark gap should be able to exert a redundant protective function with an increased protection level without an ignition aid. Derivation of a display function from the shutdown behavior of fuses is beyond the DE 38 31 935 A1 , of the DE 197 51 470 A1 or the DE 32 28 471 A1 previously known.

The U.S. Patent 6,157,529 discloses the interruption of a circuit by means of the disconnection of a fuse and a holding coil of a switch.

Ignition aids, as in the DE 199 14 313 A1 described, are also used in combination arresters. With these arresters, the starting aid itself can be designed as an independent overvoltage protection device, which activates the short-circuit element, generally a spark gap, only at the risk of its own overload via a trigger function. A combination arrester is for example in the DE 198 38 776 C2 shown.

From the CH 238 916 A is a safety device for surge arrester with voltage-dependent characteristic previously known.

According to the local solution, a securing element is bridged by a valve-like acting switching element, through which the securing element is relieved of surge currents. Furthermore, there are means which interrupt the circuit of the arrester when the fuse element responds.

From the foregoing, it is therefore an object of the invention to provide an advanced overcurrent protection device for use in overvoltage protection devices with higher rated voltages in the range of 440 V to 760 V and more, in combination with a mechanical trigger for a display and fuses for overload protection. The possibility should be created, using geometrically identical housing, display and mounting parts at different voltage levels to make an economical and functional meaningful design of the active parts, so that an easy adaptability to different uses and applications is given.

The solution of the object of the invention is achieved by the feature combination according to claim 1, wherein the dependent claims represent expedient refinements and developments.

It is assumed that the fuse elements, in particular fusible elements, split into a series circuit of several fuses, which are in addition to the electrical connection partially in a mechanical series and on the other hand partially in a mechanical parallel compound. By thus made division of the fuse arrangement arise various possibilities of geometric design and thus for optimal space utilization in otherwise used standard housings.

The division also allows a large variance in terms of residual voltage behavior, rollover protection, current limitation, the actual performance and the necessary distances to vulnerable other components, in particular a trigger circuit.

Thus, a series connection of a plurality of fuse elements is provided which form a geometrically predetermined, mechanical and electrical connection.

This series circuit according to the invention comprises a mechanical and electrical parallel composite of fusible elements, wherein at least one of the fusible elements of the parallel compound comprises a firing pin as a mechanical trigger for actuating a function display.

A first part of the series combination is located on one side of a wiring substrate, in particular a printed circuit board, and a second part of the series compound is located on a second, the first opposite side of the wiring substrate.

The first part of the series composite comprises at least two cylindrical individual fuses, which are mechanically and electrically connected by a conductive cylinder on the end faces and connecting caps present there. This mechanical and electrical connection with the help of conductive Cylinder is only in the area of the mechanical connection caps, so that the insulation and separation distances are maintained.

The composite of the cylindrical individual fuses with the conductive connecting cylinder may be coated by an insulating material, in particular by a shrink tube.

The second part of the series network comprises the already mentioned parallel network, wherein the parallel network is predominantly surrounded by a protective housing to which further functions, which are described below, can be assigned.

The connection caps of the fusible elements of the parallel connection are electrically and mechanically connected and merge into a connection extension, which in each case allows mounting on the wiring carrier.

The free ends of the individual fuses of the first part of the series composite also have connection caps with Lötfähnchen or tab-like extensions.

To adapt to the nominal voltage ranges, it is possible to replace one or more of the individual fuses or fusible elements by a conductive, in particular metallic, geometrically diameter-matched cylinder. The cylinder may also have a predetermined impedance.

In a preferred embodiment, the wiring carrier has an elongate, rectangular shape with screw connection lugs attached to the narrow sides.

The first part of the series composite is at a longitudinal outer edge, with this substantially laterally terminating, located on the wiring carrier.

The second part of the series composite, containing the parallel connection, is arranged essentially at right angles to the longitudinal axis of the first part of the series combination on the wiring carrier.

The protective housing is open to the longitudinal edge of the wiring substrate, to allow an exit of the firing pin and an operative connection of the firing pin towards a spring-biased indicator slide.

The protective housing has on its upper side facing away from the wiring substrate a color-coded indicator surface or an indicator surface extension, which is integrally formed on the housing. In this way, based on a viewing window in a cap or an outer housing, which reveals a view of the top of the protective housing, a functional state can be displayed by a slide either the view of the top releases or blocks this view.

So it has the protective housing on the one hand, the function of the isolation of the parallel compound and serves the purpose of retaining elements in the event of triggering this fuse. Furthermore, the housing serves for the aforementioned formation of an indicator surface or the reception of an indicator surface extension.

The wiring carrier is preferably mountable on the upper side of a housing, wherein the housing accommodates in its interior an arrangement of surge arresters, in particular spark gaps. This arrangement of surge arresters, in particular spark gaps is in series connection.

One of the spark gaps of the device may be triggerable, in which case the trigger circuit is on the wiring carrier.

The housing for receiving the spark gaps has on its upper side over a longitudinal edge a trough-like recess, in which the first part of the series compound dips, in order to effect a protective and insulating function of the first part of the series compound.

The overall arrangement of spark gaps mounted in the housing, wiring substrates with electrical elements located on top of the housing, and the series connection of multiple fuses is surrounded by an insulating cap, wherein the cap has the aforementioned window for detecting the functional state with respect to the indicator surfaces.

The overcurrent protection device according to the invention is characterized by a modular design with selected fuses for series connection, to effect a slight adaptation to different nominal voltages.

The display slider, which is spring-biased and can be released from the firing pin of the parallel connection, has a display surface which releases or obscures a color-deviating indicator surface, in particular the indicator surface of the top of the protective housing.

Furthermore, the display slider has an extension, which extends in the longitudinal direction beyond the narrow side of the wiring substrate, in order to interact there with a telecommunications contact in operative connection.

The fusible elements which can be used in the series connection of the overcurrent protection device consist of individual fuses which are inexpensive to manufacture, in each case, for example. for a voltage level of 250 V.

For the first part of the series connection, at least two of the fuses are connected together by a precisely fitting cylinder. The cylinder may preferably be a metal cylinder, which in addition to the electrical connection also takes over the mechanical fixing and the necessary mechanical stabilization of the corresponding part of the series connection. The number of connection elements is less by this type of connection than in a simple series connection of individual electrical fuses, each of which is e.g. be connected by soldering to a circuit board.

The distance between the remaining connection elements or end caps of the fuses is considerable, which makes it easier to maintain separation distances and significantly reduces the risk of bridging.

The preferred arrangement of the above-described series connection on the underside of the wiring substrate also provides space on the component side, in addition to sufficient separation distances on the wiring substrate. the opposite side, on the one hand on the volume savings and on the other hand by avoiding critical approximations between the overload-endangered elements and the protective device. The series connection of the fuses provides a further advantage, which is that two connection legs or connection feet are saved in the board, due to the connection of the part fuses with a conductive, in particular brass sleeve.

The first part of the series connection is separated at the top by the board from the components of the ignition circuit and on the bottom by the trough-like expression of the housing. This results in a quasi a complete insulating enclosure of the protective device. This prevents in the event of an error Berußung that may occur, and it will protect the separation sections of the ignition circuit when the release of gas or plasma from the fuse from flashovers.

The parallel part arrangement representing the second part of the series combination is preferably designed as in the German patent application DE 10 2006 026 711.7 described.

The fuses used as fuses of the parallel connection and also of the series combination preferably have the same fusible conductor at maximum rated voltage. This ensures an almost simultaneous response of all fuses for adiabatic loads and loads in which the axial heat dissipation dominates over the radial heat output.

The characteristic of the series connection of the fuses thus corresponds to a partial area fuse. The dimensions of such a series connection are considerably smaller with comparable switching capacities than with individual fuses, eg for a nominal voltage of 690 V.

In addition to the above-mentioned space saving allows the division of the fuse into several subunits and a very flexible arrangement of the individual functional units with respect to the position and location with respect to the wiring substrate.

At desired lower rated voltages, one or more fuses of the series assembly can be replaced by a simple metallic cylinder. In addition to the cost reduction, this also leads to a reduction of the residual voltage and thus supports the desired basic function of the arrester. By a two-sided arrangement of metal cylinders in addition to a real fuse in the series combination also the current force effect can be reduced to the fusible conductor, whereby higher pulse currents can be supported.

Through the use of the above-mentioned impedance-affected cylinder and the requirements for the switching capacity of the actual fuse can be reduced, since the prospective short-circuit current is limited by the impedance.

Further advantages of the modular design of the inventive overcurrent protection device for ignition aids of arresters with identical geometrical arrangements are described in the following embodiment.

Fig. 1 und 2

eine Darstellung des ersten Teils des Reihenverbunds von Schmelzelementen;

Fig. 3

eine Draufsicht auf das Gehäuse mit eingeschlossenen Funkenstrecken und erkennbarer muldenartiger Ausnehmung an der Oberseite des Gehäuses;

Fig. 4

eine Seitenansicht einer Anordnung mit Gehäuse sowie Verdrahtungsträger, welche u.a. die Triggerschaltung sowie die Überstromschutzeinrichtung aufnimmt, und

Fig. 5

eine Darstellung ähnlich derjenigen nach Fig. 4, jedoch in perspektivischer Form.

Hereby show:

Fig. 1 and 2

a representation of the first part of the series of fused elements;

Fig. 3

a plan view of the housing with enclosed spark gaps and recognizable trough-like recess at the top of the housing;

Fig. 4

a side view of an arrangement with housing and wiring support, which inter alia, the trigger circuit and the overcurrent protection device receives, and

Fig. 5

a representation similar to that after Fig. 4 but in a perspective form.

The overcurrent protection device according to the invention comprises a series connection of a plurality of fuse elements, which form a geometrically predetermined, mechanical and electrical composite.

A first part of the series composite comprises two individual cylindrical fuses 1 and 2. These two individual cylindrical fuses 1 and 2 are mechanically and electrically connected, for example, by a conductive, preferably metallic cylinder 3 on the end faces 4 and connection caps 5 present there. connected by clamping or soldering.

The resulting composite of the cylindrical individual fuses 1 and 2 with the connecting cylinder 3 is coated with an insulating shrink tube 6 (see Fig. 2 ).

The free ends of the individual fuses 1 and 2 likewise have connecting caps 5, but with soldering lugs 5 a, which serve for electrical connection and mechanical fixing on a printed circuit board.

The series connection according to the invention further comprises a mechanical and electrical parallel composite of fusible elements, wherein at least one of the fusible elements of the parallel composite has a firing pin as a mechanical trigger. The mechanical release can be embodied as a wire-shaped release part, whereby preferably this wire of the release part is connected in parallel over a part of the entire overcurrent protection device, which has the advantage that the coordination of the current commutation and the switching capacity is limited to this part of the protection.

In a parallel circuit to the entire fuse arrangement, ie parallel to all partial fuses, the fuse element of the indicator fuse should have the full switching capacity, which is possible, but leads to higher costs.

In one embodiment, the fusible link of the fuse to which the indicator is connected in parallel may be provided with a minimally lower fuse integral to ensure a reliable indication even at low overloads.

Since the complete outgassing of the indicator fuse or the throwing away of parts of the indicator can be avoided only with great effort, there is basically the danger of the outer flashover of the fuse arrangement at high voltages.

To counteract this danger, the indicator part, ie the parallel compound, with an additional housing 7 (see Fig. 4 and 5 ) Mistake.

This housing 7 blocks the external flashover and reduces the risk that can be caused by released indicator parts (firing pin), considerably.

Like from the Fig. 4 can be seen, the housing 7 is preferably arranged at right angles to the longitudinal axis of the wiring substrate 8.

The first part of the series assembly 9, comprising the individual locks with connection cylinder and protective coating, is located on the underside of the wiring substrate 8, wherein the second part of the series assembly, which is located in the housing 7, is disposed on the top of the wiring substrate 8.

From the illustration to Fig. 4 It can be seen that the wiring support 8 has an elongated, rectangular shape with screw connection lugs 10 attached to the narrow sides, wherein the first part of the series assembly 9 is located at a longitudinal outer edge, substantially laterally terminating therewith.

The protective housing 7 is open to the longitudinal edge of the wiring substrate 8, to an outlet of the firing pin therein and a Enable operative connection to a spring-biased indicator slide 11.

The protective housing 7 has, on its upper side facing away from the wiring support 8, a color-coded indicator surface 18, e.g. red, or has an indicator surface extension extending from the housing 7.

The wiring support 8 is mountable on the upper side of a housing 12, wherein in the housing 12 there may be a series-connected spark gap arrangement.

At least one spark gap of the spark gap arrangement can be triggered and the trigger circuit can be located on the wiring carrier. The contacting between the wiring carrier and the spark gap to be triggered can take place via a contact spring which extends through a recess 13 in the housing 12.

Furthermore, the spark gap housing 12 has on its upper side a trough-like recess 14, in which the first part 9 of the series compound dips to effect a protective and insulating function (see Fig. 3 and 4 ).

The overall assembly may be surrounded by an insulating cap, the cap having a viewing window to allow a view of the top of the housing 7 and the display slider 11, respectively.

The display slider 11 has a display surface 15. This display area may e.g. have a green color that signals the condition "in order".

If the display slider moves as shown in the illustration Fig. 5 to the left, the underlying top of the housing 7, which is designed differently colored, released and signaled an error condition.

The display slider 11 also has an extension 16 which extends in the longitudinal direction over the narrow side of the wiring substrate 8 in order to be in operative connection with a telecommunications contact 17.

In the region of the extension 16 of the indicator slide 11 has a thorn-like shape, which receives a helical compression spring, which is supported against the spark gap housing 12 to produce the necessary bias.

LIST OF REFERENCE NUMBERS

1; 2

cylindrical single lock

3

connecting cylinder

4

front

5

connection cap

5a

Lötfähnchen

6

coating

7

Housing for parallel connection

8th

wiring support

9

first part of the series network

10

Schraubanschlusslasche

11

display slide

12

Spark gap housing

13

Recess for trigger contact

14

trough-like recess

15

display area

16

extension

17

telecomm

18

indicating surface

Claims (20)

1. Overcurrent protection unit for use in overvoltage protection devices having higher rated voltages in combination with a mechanical trigger for a display and fusible elements for the overload protection, wherein a series circuit consisting of a plurality of fusible elements is provided forming a geometrically prespecified mechanical and electrical compound,
   characterized in that
   the series circuit comprises a mechanical and electrical parallel compound of fusible elements, wherein at least one of the fusible elements of the parallel compound comprises a striker as a mechanical trigger.
2. Overcurrent protection unit according to claim 1,
   characterized in that
   a first part (9) of the series compound is located on one side of a wiring carrier (8) and a second part of the series compound is located on a second side of the wiring carrier (8) which is opposite the first side.
3. Overcurrent protection unit according to claim 2,
   characterized in that
   the first part of the series compound comprises at least two cylindrical single fuses (1; 2) which are mechanically and electrically connected by a conductive cylinder (3) on the front sides (4) and connection caps (5) provided there.
4. Overcurrent protection unit according to claim 3,
   characterized in that
   the compound of cylindrical single fuses (1; 2) is covered by an insulating heat-shrinkable sleeve or the like material (6).
5. Overcurrent protection unit according to one of claims 2 to 4,
   characterized in that
   the second part of the series compound comprises the parallel compound, wherein the parallel compound is mainly surrounded by a protective housing (7).
6. Overcurrent protection unit according to claim 5,
   characterized in that
   the connection caps of the fusible elements of the parallel compound each extend electrically and mechanically connected into a connecting prolongation, which allow a mounting on the wiring carrier (8), specifically a circuit board.
7. Overcurrent protection unit according to claim 3 or 4,
   characterized in that
   the free ends of the single fuses (1; 2) comprise connection caps (5) with soldering lugs (5a).
8. Overcurrent protection unit according to one of claims 3 to 7,
   characterized in that
   one or more of the single fuses (1; 2) or fusible elements can be replaced by a conductive, specifically metallic, geometrically adapted cylinder.
9. Overcurrent protection unit according to one of claims 2 to 8,
   characterized in that
   the wiring carrier (8) has an elongated rectangular shape with screw connection lugs (10) mounted on the narrow sides, wherein the first part (9) of the series compound is arranged on a longitudinal outer edge substantially laterally flush with the same.
10. Overcurrent protection unit according to claim 9,
    characterized in that
    the second part of the series compound, which includes the parallel compound, is arranged on the wiring carrier (8) substantially at right angles to the longitudinal axis of the first part (9) of the series compound.
11. Overcurrent protection unit according to one of claims 5 to 10,
    characterized in that
    the protective housing (7) is open towards the longitudinal edge of the wiring carrier (8) in order to allow the striker to emerge as well as an operative connection to a springloaded display slide (11).
12. Overcurrent protection unit according to claim 11,
    characterized in that
    the protective housing (7) has a colored indicator surface or an indicator surface prolongation on its upper side facing away from the wiring carrier (8).
13. Overcurrent protection unit according to at least one of claims 2 to 12,
    characterized in that
    the wiring carrier (8) can be mounted on the upper side of a housing (12), wherein a spark gap assembly can be provided in the housing (12).
14. Overcurrent protection unit according to claim 13,
    characterized in that
    the spark gap assembly is provided as a series circuit.
15. Overcurrent protection unit according to claim 14,
    characterized in that
    one of the spark gaps of the assembly is triggerable and the trigger circuit is located on the wiring carrier (8).
16. Overcurrent protection unit according to one of claims 2 to 12 and 13 to 15,
    characterized in that
    the spark gap housing (12) has a depression-like recess (14) on its upper side, into which the first part of the series compound immerges so as to effect a protective and insulating function.
17. Overcurrent protection unit according to one of claims 13 to 16,
    characterized in that
    the total assembly is surrounded by an insulating cap.
18. Overcurrent protection unit according to one of claims 1 to 13,
    characterized by
    a modular structure with selected fusible elements for the series circuit so as to achieve an easy adaptation to different rated voltages.
19. Overcurrent protection unit according to claim 11 or 12,
    characterized in that
    the display slide (11) comprises a display surface (15) which exposes or covers an indicator surface of a different color.
20. Overcurrent protection unit according to claim 19,
    characterized in that
    the display slide (11) comprises a prolongation (16) which extends in the longitudinal direction over the narrow side of the wiring carrier (8) in order to become operatively connected to a remote signaling contact (17).

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