EP2983191A1 - Assembly for detecting electrical arcs in a low voltage network - Google Patents

Abstract

The inventive arrangement for detecting arcing in a low-voltage network has a fire protection switch (10), with a housing (13) in which a first connection element (11) for electrical contact with an external neutral conductor, and a second connection element (12) for electrical Contacting an external phase conductor are recorded and held. Furthermore, the arrangement has an electrical first connection element (20) which can be inserted into the first connection element (11) in order to realize an electrically conductive connection to a further protective switching device (40) which can be coupled to the arrangement. Furthermore, the arrangement has a protective element (30) which can be fastened to the housing (13) of the fire protection switch (10), wherein the connecting element (20) is positively received and held in the assembled state by the protective element (30), whereby a contact protection for the Connecting element (20) is realized. By the electrical connection of the fire protection switch (10) with the further protective switching device (40) is not guided within the housing (13) of the fire protection switch (10), but - by means of the first connecting element (20) - externally, i. outside the housing (13) of the fire protection switch (10), realized, the heating of the fire protection switch (10) is significantly reduced in the energized state. In addition, the assembly of the fire protection switch (10) is easier and more efficient executable.

Description

The invention relates to an arrangement for detecting arcing faults in a low-voltage network.

In electrical installation technology, the term "fire protection switch" is understood to mean a protective device for protection against faulty or arcing faults. Such arc fault protection devices are used in low-voltage networks to protect the electrical installation technology from damage caused by arc fault and their thermal consequences - such as cable fires.

An arc fault, for example, at a defective point of an electrical line, such as a loose cable clamp, or due to a cable break occur. If the arc occurs electrically in series with an electrical load, the normal operating current is usually not exceeded because it is limited by the consumer. For this reason, the arc is not detected by a conventional overcurrent protection device, such as a fuse or a circuit breaker. This is particularly problematic at high operating currents as well as existing for a long time arcs, since in these cases, there is a risk of fire due to the high temperatures.

To determine whether an arc is present, both the voltage curve and the current profile over time are measured by the fire protection switch and evaluated by means of digital signal processing. In particular, the current profile has at Störlichtbögen characteristic, high-frequency components. In the evaluation, however, it should be noted that regular fluctuations in the current waveform as well as in normal operation occurring harmonics or transient current waveforms Do not cause a faulty tripping of the fire protection switch when switching on consumers. For this reason, fire circuit breakers have relatively complex algorithms for monitoring the electrical installation as well as for detecting possible arcing faults.

In the (English-language) specialist literature, such devices for detecting arcing faults are referred to as Arc Fault Detection Device (abbreviated AFDD). In North America, where the so-called UL standard (Underwriters laboratories, standard with 110 V mains voltage) prevails, the term Arc Fault Circuit Interrupter (abbreviated AFCI) is common. In the United States, arc circuit breakers are even compulsory to detect, based on predetermined criteria, whether there may be an electric arc in a circuit. For this purpose, the arc protection switches used there have their own isolating contact, which is opened in the event of the presence of an arc. The principles used in these arc circuit breakers are disclosed, for example, in US patents US 5,729,145 such as US 6,031,699 described.

In most European countries, where the IEC standard (International Electrotechnical Commission, standard with a mains voltage of 230 V) is prescribed, arc circuit breakers are not absolutely necessary. In the past, circuits in IEC technology have usually been protected by means of fault current circuit breakers and circuit breakers. However, protection against arcing faults is therefore not feasible.

Nevertheless, in order to realize effective protection against arcing faults, additional circuit breakers against arcing faults, so-called fire protection switches, are also being used here in Germany. In contrast to the models available on the US market, however, these fire circuit breakers usually have no separate isolating contacts, but are usually used as an independent module, the so-called AFD block, with another Protective device, such as a circuit breaker (so-called LS switch) or a combined circuit breaker / residual current circuit breaker (so-called RCD / MCB), combined. This combination of the two devices then forms the AFDD circuit breaker. In low-voltage electrical installation technology, these protective switching devices are also referred to as "DIN rail mounted devices". This term is due to the fact that in an electrical distribution manifold often a plurality of such modular devices are arranged side by side "in a row".

When combining a fire circuit breaker with the other protection switching device, an electrical connection of the two devices is required to realize a common feed. For this purpose, the two phase connections and the two neutral conductor connections of the two devices are electrically connected to each other. For easier combination of the two devices, the fire protection switch for this purpose already electrical connection means, the first ends of which are located inside, i. within a switch housing of the fire protection switch, are electrically connected to the terminals, and whose second ends are led out of the housing to be electrically connected to the terminals of the further protective switching device. As electrical connection means mostly enamel-insulated copper wires are used, which are already bent such that the second ends are already in the region of the connection elements of the coupled further protective switching device.

However, the problem here is that of the current-carrying elements, ie the connecting conductors and the electrical connection means, outgoing heat generation, as the electronic components used to monitor the electrical installation and for detecting arcing faults are relatively sensitive to heat. The accuracy of the evaluation can be significantly influenced by a heat development.

It is therefore the object of the present invention to provide an arrangement for detecting arcing faults in a low-voltage network, which is characterized by an improved thermal behavior and thus by improved accuracy.

This object is achieved by the arrangement according to the invention according to independent claim 1. Advantageous embodiments are the subject of the dependent claims.

The arrangement according to the invention for detecting arcing faults in a low-voltage network has a fire protection switch, with a housing in which a first connection element for electrical contacting with an external neutral conductor and a second connection element for electrical contacting with an external phase conductor are accommodated and held. Furthermore, the arrangement has an electrical first connection element which can be inserted into the first connection element in order to realize an electrically conductive connection to a further protective switching device which can be coupled to the arrangement. Furthermore, the arrangement has a protective element, which can be fastened to the housing of the fire protection switch, wherein the connecting element is received and held in the assembled state non-positively and / or positively by the protective element, whereby a contact protection for the connecting element is realized.

In the arrangement according to the invention, the electrical connection of the fire circuit breaker with the other protective switching device is not performed within the housing of the fire circuit breaker, but - with the help of the first connecting element - externally, ie outside the housing of the fire circuit breaker realized. In this way, the heating of the fire circuit breaker, which is problematic in an internally, ie within the housing, guided electrical connection, significantly reduced. Furthermore results in the arrangement according to the invention the advantage that the cost of mounting the fire circuit breaker is significantly reduced because the first connection element only inserted and no longer - as in the case of a rigid, internally guided copper wire conductor - must be threaded into the housing.

The further protective switching device may be, for example, a circuit breaker, a residual current circuit breaker or even a combination of circuit breaker and residual current circuit breaker. However, a prerequisite is that this further protective switching device has its own isolating contacts for interrupting the electrical lines - phase line and neutral conductor.

In an advantageous further connection of the arrangement, the frictional and / or positive retention of the connecting element is realized by means of a retaining contour formed on the protective element.

With the help of the retaining contour, the connecting element can be attached in a simple manner to the protective element. In this case, by means of the retaining contour, both a non-positive connection acting in a first direction and a second connection oriented in a direction oriented transversely to the first direction are positively connected, ie. a kind of locking connection, between the connecting element and the protective element feasible.

In a further advantageous further connection of the arrangement, the first connecting element has a substantially U-shaped configuration, with a first leg, a second leg and a connecting region connecting the two legs, wherein the first leg for insertion into the first connecting element, and the second Legs are designed for contacting with the protection device.

Thus, the first connecting element has a rigid, predefined shape, which can be produced in a simple manner and is characterized by easy handling. Furthermore, a higher stability of the first connecting element is achieved by the U-shaped shaping.

In a further advantageous further connection of the arrangement, the connection region is substantially U-shaped.

Also, the U-shaped shaping of the connection area a higher stability is achieved. This is particularly advantageous because the connection area serves, inter alia, to realize the non-positive and / or positive retention of the connecting element on the protective element by means of the protective element formed on the corresponding inversely shaped retaining contour.

In a further advantageous further connection of the arrangement, the connecting element is designed as a sheet metal bent part. The design of the connecting element as a sheet metal bent part represents an extremely cost-effective design.

In a further advantageous continuation of the arrangement, the fire protection switch has an electrical second connection element, the first end of which is electrically conductively connected to the second connection element within the housing of the fire protection switch, and whose second end is led out of the housing to form an electrically conductive connection to the other To realize a protective switching device.

The further protective switching device may be, for example, a circuit breaker, a residual current circuit breaker or even a combi device, consisting of a circuit breaker and a residual current circuit breaker, act. A prerequisite, however, is that this further protective switching device has its own isolating contacts for interruption the electrical lines - phase line and neutral - has.

In a further advantageous further connection of the arrangement, the first connection element is designed as an electrical terminal with a clamping screw for clamping the neutral conductor, wherein the connecting element by tightening the clamping screw frictionally connected to the terminal. With the aid of the screw-type terminal, an electrically conductive connection between the neutral conductor and the connecting element can be realized in a simple manner.

In a further advantageous further connection of the arrangement, the second connection element is designed as an electrical connection terminal with a clamping screw for clamping the phase conductor. Screwable terminals represent a robust and simple embodiment for realizing a connection element of a protective switching device.

In a further advantageous further connection of the arrangement, the protective element can be fastened to the housing with the aid of at least one latching connection.

Locking connections provide a robust, inexpensive and easy to implement way to attach the protective element to the housing of the fire circuit breaker. Locking connections are usually made of a latching hook and a counter element - for example, a detent opening - which cooperates with the latching hook such that in this way a positive connection of the two connection partners is formed. In the present case, the latching hook can be formed both on the side of the protective element and on the sides of the housing, with a corresponding arrangement of the counter-element on the respective other connection partner.

In a further advantageous further connection, the arrangement further comprises a protective switching device, which with the Fire protection switch is coupled, wherein with the aid of the first connecting element, an electrically conductive connection between the first connection element of the fire protection switch and a first connection element of the protective switching device is realized.

While the fire circuit breaker without the coupled further protection switching device for simple retrofitting an existing low-voltage electrical installation for effective protection against fault or fault arcs is used, the coupled embodiment, consisting of a fire protection switch with a circuit breaker device already coupled thereto, primarily on the use in a newly built low-voltage electrical installation. By coupling to an installable module assembly costs for the equipment of an electrical distribution manifold can be significantly reduced.

In the following, an embodiment of the arrangement will be explained in more detail with reference to the accompanying figures. In the figures are:

characters

1A to 1D

schematic representations of a known fire circuit breaker and its components;

FIGS. 2A and 2B

schematic representations of the first connecting element and the protective element;

FIGS. 3A to 3C

schematic representations of the arrangement according to the invention.

In the various figures of the drawing, like parts are always provided with the same reference numerals. The description applies to all drawing figures in which the corresponding part can also be recognized.

The Figures 1A to 1D schematically show a known from the prior art fire protection switch 10. In FIG. 1B the fire protection switch 10 is shown with the housing 13 open. In the housing 13, a first connection element 11 for electrical contacting with an external neutral conductor, and a second connection element 12 for electrical contacting with an external phase conductor are received and held in the region of the lower narrow side. The two connection elements 11 and 12 are accessible from the outside via two openings 14 formed in the lower narrow side of the housing 13.

Figure 1A shows a detailed representation of an electrical connection element, which is designed as a terminal, more precisely: as a screw terminal. The terminal has a clamping frame 17 and a clamping screw 15, which in a first direction L relative to the clamping frame 17 is movable. In the lower region of the clamping frame 17, an electrical connection piece 18 is inserted into the clamping frame. With the connector 18, an electrical conductor 19 is electrically connected, for example by means of welding or brazing. By a movement of the clamping screw 15 in the first direction L, an external electrical connection line, for example a phase or neutral line (not shown), between the clamping screw 15 and the connector 18 are clamped to an electrically conductive connection between the conductor and the fire protection switch 10 to realize. In principle, however, it is also possible not to form the first connection element 11 and / or the second connection element 12 as a screw terminal, but otherwise, for example as a plug connection.

In the present case, the electrical conductor 19, which in Figure 1C is shown in a detailed representation, in addition, an electrically conductive connection of the neutral terminal of the fire protection switch 10 with a to be coupled to the fire protection switch 10, another protective switching device - for example a circuit breaker, a residual current circuit breaker or a combination of both switching devices - manufacture. For this purpose, the electrical conductor inside the device, ie within the housing 13, electrically conductively connected to the connector 18 and at least partially guided within the housing 13. In the area of the lower narrow side, ie below the openings 14, the conductor 19 comes out of the housing 13 and is led outside the housing 13 to an electrical connection element (not shown) of the further protective switching device to be coupled. Due to the cramped space within the fire circuit breaker 10 a complex current flow is required, which is why the head 19 bent several times from a piece of wire and thereby adapted to the geometric conditions within the housing 13 of the fire circuit breaker 10.

FIG. 1D finally shows the known from the prior art fire protection switch 10 with a mounted in the narrow side protection element 30. The protective element 30 is latched to the narrow side of the housing 13 and serves to cover the electrical conductor 19. In this way, a contact protection of the electrical conductor 19 realized.

The FIGS. 2A and 2B show schematic representations of the first connecting element 20 and the protective element 30. Figure 2A shows the two parts in the disassembled state, while in FIG. 2B are shown in the assembled state. The first connecting element 20 has a substantially U-shaped configuration, with a first leg 21 a second leg 22 and a connecting portion 23 connecting the first leg 21 and the second leg 22. The first leg 21 is for insertion into the first connecting element 11 of the fire protection switch 10 is provided and formed. Likewise, the second leg 22 for insertion into a first connection element 41 of a to be coupled to the fire protection switch 10 further protective switching device 40 (see FIG. 3C ) provided and trained. The connection area 23 is also designed substantially U-shaped, whereby a sufficient stability of the first connecting element 20 is achieved. Therefore, the first connecting element 20 can also be produced in a simple and cost-effective manner as a stamped part or as a sheet metal bent part.

With the help of the protective element 30, a contact protection for the electrically conductive first connection means 20 is realized. The protective element 30 is therefore made of a non-conductive material, such as plastic, and is attached to the narrow side of the fire circuit breaker housing 13. For this purpose, the protective element 30 has a latching hook 36, which with a formed on the narrow side of the housing 13 latching opening 26 (see 3A and Figure 3C ) is locked. For receiving the first connecting element 20, the protective element 30 on its in the assembled state of the narrow side of the fire circuit breaker housing 13 facing inside 32 a holding contour 31, which serves for the positive and / or non-positive fixing of the first connecting element 20. Since the first connecting element 20 is held by the retaining contour 31 predominantly in the region of the connecting region 23, the retaining contour 31 of the geometric contour of the connecting region 23 is designed accordingly. For this purpose, the holding contour has essentially two parallel, U-shaped guide webs, between which the connecting region 23 can be inserted. As a result, a positive connection is already feasible. For positive fixing of the first connecting means 20 in the insertion direction, one or more locking means can be formed on the guide webs, which prevent the connecting means 20 from slipping out.

In the FIGS. 3A to 3C is the inventive arrangement, which consists essentially of the fire protection switch 10, the first connecting element 20 and the protective element 30 and - FIG. 3C shown - the further protection switching device 40 is shown schematically. FIG. 3A shows a so-called The housing 13 of the fire protection switch 10 has in the region of its narrow side two openings 14, behind which the first connection element 11 and the second connection element 12 are arranged , Through the openings 14 of the fire protection switch 10 with the electrical connection cables (phase line and neutral line) of an electrical installation is electrically connected. With regard to their position corresponding thereto, the protective element 30 also has two openings 34. Also in the region of the narrow side, a second connecting element 25, which is electrically conductively connected within the housing 13 to the second connecting element 12, led out of the housing 13 through a further opening. Above this further opening, a latching opening 26 for latching the protective element 30 is formed on the narrow side, for this purpose, the latching hook 36 integrally formed on the protective element 30 engages in the latching opening 26.

FIG. 3B shows one too FIG. 3A Corresponding representation of the arrangement in which the individual parts are mounted. The first connecting element 20 is inserted on the one hand into the retaining contour 31 of the protective element 30, and on the other hand with its first leg 21 into the first connecting element 11 of the fire protection switch 10. In this way, an electrically conductive connection to be coupled to another protective device 40 can be realized. The protective element 30 is fixed by means of the latching connection 26, 36 on the narrow side of the fire protection switch housing 13, so that the inner side 32 of the protective element 30 faces the narrow side of the housing 13. In this illustration, it is clear that with the aid of the protective element 30 a contact protection for both the first connecting element 20, and for the second connecting element 25, is realized.

In FIG. 3C is finally in the FIGS. 3A and 3B illustrated arrangement with another protective device 40th coupled, wherein the protective element 30 has been omitted. It becomes clear that, on the one hand, the first connection element 30 electrically conductively connects the first connection element 11 of the fire protection switch 10 to the first connection element 41 of the further protection switching device 40, by being plugged into the connection elements 11 and 41 from the outside. By contrast, the second connection element 12 of the fire protection switch 10 is electrically conductively connected to the second connection element 42 of the further protection switching device 40 by the lead out of the housing 13, rigid second connecting element 25. In this way, a subsequent installation of the fire circuit breaker 10 to the other protective device 40 an existing electrical installation with relatively little effort is possible.

LIST OF REFERENCE NUMBERS

10

Fire protection switch

11

first connection element

12

second connection element

13

casing

14

opening

15

clamping screw

16

latching opening

17

clamping frame

18

connector

19

ladder

20

first connecting element

21

first leg

22

second leg

23

connecting area

25

second connecting element

26

latching opening

30

protection element

31

retaining contour

32

inside

33

outside

34

opening

36

latch hook

40

Protection device

41

first connection element

42

second connection element

L

first direction

Claims (10)

Arrangement for detecting arcing faults in a low-voltage network, comprising: a fire protection switch (10) having a housing (13) in which a first connection element (11) for electrical contacting with an external neutral conductor and a second connection element (12) for electrical contacting with an external phase conductor are received and held, - An electrical first connection element (20) which can be inserted into the first connection element (11) in order to realize an electrically conductive connection to a further protective switching device (40) which can be coupled to the arrangement, a protective element (30) which can be fastened to the housing (13) of the fire protection switch (10), wherein the connecting element (20) in the assembled state is received and held non-positively and / or positively by the protective element (30), whereby a contact protection for the connecting element (20) is realized. Arrangement according to claim 1,
in which the frictional and / or positive retention of the connecting element (20) by means of a protective element (30) formed holding contour (31) is realized. Arrangement according to one of the preceding claims,
in which the first connecting element (20) has a substantially U-shaped configuration, with a first leg (21), a second leg (22) and a connecting region (23) connecting the two legs (21, 22), the first one Leg (21) for insertion into the first connection element (11), and the second leg (22) for contacting with the protective switching device (40) are formed. Arrangement according to claim 3,
wherein the connecting portion (23) is substantially U-shaped. Arrangement according to one of the preceding claims,
in which the connecting element (20) is designed as a sheet metal bent part. Arrangement according to one of the preceding claims,
in which the fire protection switch (10) has an electrical second connection element (25) whose first end is electrically conductively connected to the second connection element (11) within the housing (13) of the fire protection switch (10) and whose second end is removed from the housing (13 ) is led out to realize an electrically conductive connection to the further protective switching device (40). Arrangement according to one of the preceding claims,
in which the first connection element (11) is designed as an electrical connection terminal (14) with a clamping screw (15) for clamping the neutral conductor, wherein the connection element (20) can be frictionally connected to the connection terminal (14) by tightening the clamping screw (15). Arrangement according to one of the preceding claims,
in which the second connection element (11) is designed as an electrical connection terminal (14) with a clamping screw (15) for clamping the phase conductor. Arrangement according to one of the preceding claims,
in which the protective element (30) can be fastened to the housing (13) with the aid of at least one latching connection (16, 36). Arrangement according to one of the preceding claims,
further comprising a protective switching device (40) which is coupled to the fire protection switch (10), wherein with the aid of the first connecting element (20) an electrically conductive connection between the first connection element (11) of the fire protection switch (10) and a first connection element (41) the protective switching device (40) is realized.

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