Circuit breaker with arc flash detection unit

Abstract

Circuit breaker (100', 100'') for a conductor system with a neutral conductor and at least one other conductor, and with a housing (10'a, 10''a; 10b) in which space is provided for each conductor, in which two separable contact elements are arranged, by which a switching contact for the respective conductor is formed, and with a unit (20) for detecting an arc and a tripping unit (22) coupled to this unit (20) for causing the switching contact for the neutral conductor to open in the event of an arc being detected according to a predetermined criterion, characterized in that the unit (20) for detecting an arc and the tripping unit (22) are arranged in the space (10'a) for the neutral conductor.

Description

[0001] The invention relates to a circuit breaker according to the preamble of claim 1.

[0002] A circuit breaker is typically provided for a specific wiring system. It is assumed that this system includes a neutral conductor and other conductors, with conventional wiring systems having either one additional conductor or three additional conductors in a three-phase system.

[0003] The function of a circuit breaker is to interrupt the flow of current through the conductors under predetermined conditions, particularly when current levels are too high. A switching contact is therefore provided for each conductor other than the neutral conductor. This is achieved using two contact elements that can be separated from each other. Typically, one contact element is fixed to the circuit breaker housing, while the other is movable relative to the fixed contact element, for example, it can pivot. This can also be referred to as a "pole".

[0004] In most circuit breakers, the neutral conductor is also a pole, meaning a switching contact is provided for a neutral conductor. For example, US Patent 2002 / 0149891 A1 discloses the use of a circuit breaker for a wiring system with a neutral conductor and another conductor, providing a tripping coil that acts on switching contacts for both conductors. While the corresponding circuit diagram is simple, the implementation is complex: building such a circuit breaker, where the common tripping coil is intended to act on both switching contacts, requires a complicated design.

[0005] There are also designs with switching contacts for all conductors, including the neutral conductor, where the switching contacts are coupled to each other via a shaft that transmits the opening impulse of one pole to the switching contact of the second. In this case, a separate trigger for the neutral conductor is not required.

[0006] The invention relates to a circuit breaker in which space is provided for each pole. Circuit breakers with these characteristics are particularly suitable when a simple design is desired. In particular, the installation space is generally the same for each conductor, namely, the same size and, at least in a certain area, the same geometric structure. For the sake of a clear and uncluttered design of the circuit breaker, it is even acceptable that the installation space for the neutral conductor is not completely filled. In particular, a separate trip coil for the neutral conductor switching contact can be omitted, as can an arc-quenching device, such as those required for the phase conductors.

[0007] From DE 10 2008 004 868 A1, it is known to provide arc flash protection functionality in a residual current circuit breaker. This includes means for detecting whether an arc flash occurs in a circuit in which the internal connecting conductors of the residual current circuit breaker are switched, and means for opening each switching contact in the event of an arc flash.

[0008] Despite all the advantages of the residual current circuit breaker from DE 10 2008 004 868 A, it is a disadvantage that a new device has to be designed to implement the idea described therein and that it is not possible to build on existing designs.

[0009] Furthermore, international publication WO 2009 / 089994 A1 discloses how to extend an existing protective switching device to include arc fault protection functionality. This functionality is integrated into a separate module, which is mechanically coupled to the protective switching device and, in the event of a trip, utilizes the disconnect contacts of the protective switching device, as the module itself does not have its own disconnect contacts. This module allows for the quick and easy addition of arc fault protection functionality to an existing electrical installation; however, the increased space requirement is a disadvantage.

[0010] The object of the present invention is to provide a circuit breaker with the functionality of arc protection, which is simply constructed and makes optimal use of the available installation space.

[0011] The problem is solved by a circuit breaker with the features of claim 1.

[0012] According to the invention, in a circuit breaker according to the preamble of claim 1, the following are arranged in the installation space for the neutral conductor: a unit for detecting an arc and a tripping unit coupled to this unit for causing the switching contact for the neutral conductor to open in the event of an arc being detected.

[0013] It is the inventor's insight that the excess space available in conventional circuit breaker designs for the neutral conductor can be used effectively to accommodate the arc detection device and an associated tripping unit. In particular, an arc can be interrupted by opening only the switching contact of the neutral conductor, followed by that of the other conductor(s).

[0014] It is also preferred that several release units for opening a switching contact for different conductors are coupled together, i.e., that the switching contacts are coupled to each other indirectly or directly. In this case, when an arc is detected, the switching contact of a phase conductor is also opened, and conversely, when the switching contact of a phase conductor opens, and in the event of an overcurrent, the switching contact for the neutral conductor is also opened. This results in all-pole disconnection.

[0015] It is preferably based on the prior art design of a miniature circuit breaker (MCB), in which, in particular, the installation space for each conductor is identical, e.g., of the same size. Preferably, the installation space for the conductors is provided in adjoining sections of the MCB housing, these sections having the same cross-sectional shape. This can be achieved by a plurality of parallel walls of the housing. The individual installation spaces can be separated from each other by partitions.

[0016] Preferably, an arc suppression unit is provided in a specific area of ​​the cross-sectional shape within the installation space for the other conductors. No arc suppression unit is required for the neutral conductor. The area of ​​the cross-sectional shape where the arc suppression unit is provided within the installation space for the other conductors is then used within the installation space for the neutral conductor for the arc detection device. Similarly, the release unit coupled to the arc detection unit is preferably arranged where a release unit is also arranged within the installation space for the other conductors.

[0017] Preferably, the triggering units comprise an (excitation) coil and an armature that can be moved by the coil.

[0018] According to the preferred embodiment, there are at least two such coils with armatures. Each coil can be used for a different purpose; for example, one coil is energized when the current through the conductor is too high, and the other coil is energized when an arc is detected by the arc detection device. Since the space for the additional coil is already available in the area of ​​the neutral conductor in the conventional design of the circuit breaker, providing two coils has no disadvantage with regard to the required installation space.

[0019] A preferred embodiment of the invention is described below with reference to the drawing, in which Fig. Figure 1 illustrates in perspective the construction of a circuit breaker according to the prior art, from which the present invention is based, Fig. 2 shows a section through the installation space for a neutral conductor in a circuit breaker according to the invention, and Fig. 3 according to Fig. 2. Realized concept based on the circuit breaker from Fig. 1 is also illustrated by a perspective view.

[0020] A circuit breaker designated 100, according to the prior art, can protect a wiring system with a neutral conductor and another conductor. The circuit breaker 100 has a housing composed of essentially two identical housing parts 10a and 10b. One housing part 10a is associated with the neutral conductor, the other housing part 10b with the conductor other than the neutral conductor. Both housing parts contain switching contacts (not shown in the figure) for interrupting a circuit (poles). Shown in the figure is a trip mechanism with a trip coil 12 and an armature 14, which is moved by energizing the coil. The trip mechanism acts on the switching contact.The present invention provides that a movement of the switching contact causes a shaft 16 to rotate, which extends into the second housing part 10a and is directly or indirectly coupled to the contact elements of the switching contact there in order to open it as well. For this reason, no separate release mechanism is required in this housing part 10a for the switching contact associated with the neutral conductor. Thus, a free space 18 is provided in housing part 10a. In the corresponding housing part 10b, the release coil and the armature 14 are provided in this space. Likewise, an arc-quenching chamber (not shown in the figure) is also provided in housing part 10b, which has no counterpart in housing part 10a. This is where the present invention comes into play. Fig. Figure 2 shows a section through a housing part 10'a of a circuit breaker 100' corresponding to housing part 10a according to an embodiment of the invention. In a space where an arc-quenching chamber is arranged for a conductor other than the neutral conductors, a unit 20 for detecting an arc is arranged. Such units are known from the prior art and are described, for example, in DE 10 2008 004 868. It is assumed here to be known how such an arc is detected when it occurs somewhere in a circuit into which the circuit breaker is connected.

[0021] At the point where a housing part is located next to the trip coil (which is separate from the neutral conductor), a trip mechanism is also arranged, designated 22. The detection device is coupled to the trip mechanism 22 such that the switching contact associated with the neutral conductor is opened when the presence of an arc is detected according to a predetermined criterion. The exact mechanism by which the tripping occurs is not important here. For this reason, a description of the mechanism is omitted. Fig. 2. The mechanism is only schematically indicated.

[0022] The mechanism used is similar to that of the circuit breaker 100. Fig. 1 is given, in which the poles are coupled to each other by a shaft. This will be explained below using a circuit breaker 100'', the internal workings of which can correspond to those of the circuit breaker 100': In the area 18, which remains free in the prior art, a coil 24 is now provided and an armature 26, which acts on the switching contact for the normal conductor. The coil 24 and the armature 26 together form a tripping device of the type in Fig. 2 shown release device 22.

[0023] There are now two ways in which the circuit breaker can be triggered: Either a conventional trip occurs due to an excessively high current; in this case, the coil 12 is energized, and the switching contact in the housing 10b is opened, and the switching contact for the normal conductor is also opened through the coupling via the shaft 16. It is also possible that an arc occurs in the circuit in which the circuit breaker 100'' is connected. This is then detected by a device for detecting the arc in the housing part 10''a (of the type of device 20). Fig. 3) is detected, and the coil 24 is energized, the armature 26 moves and opens the switching contact for the normal conductor. Through coupling with the shaft 16, the second switching contact in the housing part 10b is also opened simultaneously.

[0024] In the 100' and 100'' circuit breakers, the available installation space is optimally utilized to additionally provide the functionality of arc detection and tripping upon such detection. Reference symbol list 10a, 10b, 10'a, 10''a Housing parts 12 Release coil 14 anchors 16 wave 18 free area 20 recording units 22 Release coil 24 coil 26 anchors 100, 100', 100'' circuit breaker

Claims

[1] Circuit breaker (100', 100'') for a wiring system with a neutral conductor and at least one other conductor, and with a housing (10'a, 10''a; 10b) in which space is provided for each conductor, in which two separable contact elements are arranged, by which a switching contact for the respective conductor is formed, and with a unit (20) for detecting an arc and a tripping unit (22) coupled to this unit (20) for causing the switching contact for the neutral conductor to open in the event of an arc being detected according to a predetermined criterion, characterized by , that the unit (20) for detecting an electric arc and the triggering unit (22) are arranged in the installation space (10'a) for the neutral conductor. [2] Circuit breaker (100'') according to claim 1, characterized by, that several release units (12, 14; 24, 26) are coupled together to cause a switching contact to open for different conductors. [3] Circuit breaker (100', 100'') according to claim 1 or 2, characterized by , that the installation space (10'a, 10''a; 10b) for the conductors is provided in adjoining sections of the housing which have the same cross-sectional shape. [4] Circuit breaker (100'), characterized by , that in an area of ​​the cross-sectional shape in the installation space for at least one further conductor an arc extinguishing unit is provided and in the same area of ​​the cross-sectional shape in the installation space (10'a) the device (20) for detection is provided for the neutral conductor. [5] Circuit breaker (100', 100'') according to claim 3 or 4, characterized by , that a release unit (12, 14, 22, 24, 26) is provided in the same area of ​​the cross-sectional shape of the installation space of all conductors. [6] Circuit breaker (100'') according to any one of the preceding claims, characterized by , that the release unit for the neutral conductor and another release unit each comprise a coil (12, 24) and an armature (14, 26) movable by the coil.

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