circuit breaker

Abstract

Circuit breakers (1), in particular low-voltage circuit breakers, with - a switch housing (2), - a first and a second connection piece (3, 4) which extend outwards through the rear of the switch housing (2) and can each be connected to a busbar, - a switching contact arranged in the switch housing (2), comprising two contact pieces which are in contact with each other when the switching contact is closed and are separated from each other when the switching contact is open, wherein the two contact pieces are each electrically connected to one of the two terminal pieces (3, 4), wherein the circuit breaker (1) has a switching device (10) with a) a first contact element (11) which is electrically connected to the first connector (3), b) a second contact element (12) which is electrically connected to the second connector (4), c) a third contact element (13) which is electrically connected to an electronic component of the circuit breaker (1), and d) a mechanical switching element (14) by actuating which the third contact element (13) can be selectively connected to the first contact element (11) or the second contact element (12), wherein the switching element (14) can be manually operated from the outside.

Description

[0001] The invention relates to a protective switch, in particular a low-voltage circuit breaker.

[0002] Circuit breakers are known, for example, as low-voltage circuit breakers. Such circuit breakers have a switch housing in which a switching contact is arranged for at least one phase conductor. When the switch is closed, the contacts of this contact are in contact with each other, and when the switch is open, they are separated. One of the contacts is movable. The circuit breaker has two terminals for each phase conductor—one on the mains side and one on the load side—which are electrically connected to the contacts inside the switch housing. These terminals typically extend through the switch housing to the outside, where they can be electrically connected to one of the main busbars on either the mains or load side.

[0003] These low-voltage circuit breakers are used to switch a selected branch of an electrical load circuit on and off. In predefined situations—for example, a continuous overcurrent condition or a short circuit—the low-voltage circuit breaker ensures a current interruption by disconnecting itself from its mains supply, thus effectively protecting the electrical load circuit from undesirable electrical conditions. The interruption of the electrical load circuit in these low-voltage circuit breakers is achieved by separating a pair of electrical contacts located inside the breaker housing.

[0004] It is often desirable for the circuit breaker to be equipped with a voltage measuring system that taps the voltage at the mains-side or load-side terminal and, if necessary, also records the voltage waveform over time. Such a voltage tap places relatively high demands on insulation and mechanical strength in order to withstand the electrical and mechanical stresses during the operation of the low-voltage circuit breaker.

[0005] German patent DE 10 2015 213 240 B4 discloses a low-voltage circuit breaker with a switch housing in which a first and a second terminal are brought out of the rear of the switch housing and can be connected to a busbar. Inside the housing, a switching contact comprising two contact pieces is arranged, each of which is electrically connected to one of the two terminals. Furthermore, a voltage measuring system is disclosed in which a first contact is connected to the first terminal, a second contact to the second terminal, and a third contact to an electronic component, wherein the third contact can be selectively connected to either the first or the second contact by changing the position of a plug / socket wire connection.

[0006] Furthermore, another circuit breaker is known from the patent application DE 2014 117 807 A1, with a switch housing in which a first and a second connection piece are led out of the rear of the switch housing and can be connected to a busbar, wherein a switching contact is arranged inside the housing, which comprises two contact pieces, each of which is electrically connected to one of the two connection pieces.

[0007] The object of the present invention is to propose a simple voltage tap that meets the high requirements in terms of insulation and mechanical strength and can be optionally located on one of the two connection pieces.

[0008] This problem is solved according to the invention by the circuit breaker according to claim 1. Advantageous embodiments of the circuit breaker according to the invention are the subject of the dependent claims.

[0009] The circuit breaker according to the invention, in particular a low-voltage circuit breaker, comprises a switch housing and a first and a second terminal piece, which extend outwards through the rear of the switch housing and can each be connected to a busbar there. Furthermore, the circuit breaker has a switching contact arranged in the switch housing, comprising two contact pieces which are in contact with each other when the switching contact is closed and are reliably separated from each other when the switching contact is open, with each of the two contact pieces being electrically connected to one of the two terminal pieces. The circuit breaker has a changeover device which in turn a) a first contact element which is electrically connected to the first connector, b) a second contact element which is electrically connected to the second connector, c) a third contact element which is electrically connected to an electronic component of the circuit breaker, as well as d) a mechanical switching element by which the third contact element can be selectively connected to the first contact element or the second contact element, wherein the switching element (14) can be manually actuated from the outside.

[0010] The switching device allows the voltage tap to be switched between the first and second terminals. This means that either the first or the second terminal is electrically connected to the third contact element – ​​and thus to the electronics, which are preferably located in the switch housing. The voltage tap is therefore already integrated into the circuit breaker, eliminating the need for any additional installation. The installer responsible for installing the circuit breaker simply needs to select, by appropriately positioning the switching element, whether the electrical potential of the mains-side or load-side terminal is to be measured relative to the potential of the circuit breaker. This significantly simplifies the commissioning of the circuit breaker.

[0011] In an advantageous further development of the circuit breaker, the switching device is arranged on a rear-mounted cover of the circuit breaker.

[0012] By replacing the cover, the changeover device on the circuit breaker can be easily retrofitted to an existing installation. To switch the voltage tap between the mains and load terminals, the circuit breaker simply needs to be pulled out, i.e., disconnected from both the mains and load terminals. This allows the mechanical switching element to be manually switched between its two positions: voltage tap at the first terminal via the first contact element, or voltage tap at the second terminal via the second contact element. This eliminates the need for a complex modification of the circuit breaker, which would involve rerouting the voltage tap from the first terminal to the second terminal, thus significantly simplifying the operation of the circuit breaker.

[0013] In a further advantageous embodiment of the circuit breaker, the first contact element and / or the second contact element and / or the mechanical switching element is arranged on a side of the cover facing the circuit breaker.

[0014] In a further advantageous embodiment of the circuit breaker, the cover has a first opening for passing through the first connecting piece.

[0015] By having at least the first connector, and possibly also the second connector, pass through the first opening of the cover, the switching device is located predominantly or even completely behind the cover, thus meeting the requirements for insulation strength and the mechanical strength of the voltage tap.

[0016] In a further advantageous development of the circuit breaker, the cover is part of the switch housing.

[0017] This significantly simplifies the design of the switch housing – and thus the circuit breaker. If the customer does not require a changeover mechanism, the cover can be omitted or replaced with a simple lid. This modularity allows manufacturing costs to be reduced across a wide range of product variants.

[0018] In a further advantageous embodiment of the circuit breaker, the mechanical switching element is designed as a slide switch or a rotary switch. Slide switches and rotary switches represent simple and cost-effective designs for implementing the switching device.

[0019] In a further advantageous embodiment of the circuit breaker, several switching poles, each with a switching contact, are accommodated and held within the switch housing. Each switching pole is assigned a first and a second connection piece, which extend outwards through the rear of the switch housing and can each be connected to a busbar, with each switching pole having its own associated switching device.

[0020] In this way, for multi-pole circuit breakers, it can be decided individually for each switching pole whether a voltage tap should be implemented there, and if so, at which terminal the voltage tap should be made. The voltage tap can be easily retrofitted to each switching pole, so that the installer can easily add the voltage tap if requirements change.

[0021] The following section explains exemplary embodiments of the circuit breaker with reference to the accompanying figures. The figures show: Fig. 1 a schematic section view of the connection side of the circuit breaker according to the invention; Fig. 2 and Fig. 3 schematic representations of a switching device of the circuit breaker according to the invention in a first switching position in different views; Fig. 4 and Fig. 5 schematic representations of a switching device of the circuit breaker according to the invention in a second switching position in different views;

[0022] In the various figures of the drawing, identical parts are always marked with the same reference symbol. This description applies to all figures in the drawing in which the corresponding part is also recognizable.

[0023] In Fig. Figure 1 is a schematic representation of a section of the connection side of a circuit breaker 1, more precisely: a low-voltage circuit breaker. The circuit breaker 1 has a switch housing 2 in which at least one switching contact (not shown) is arranged, the contacts of which are in contact with each other when the switching contact is closed and are separated from each other when the switching contact is open. The circuit breaker 1 can be, as in Fig. 1 shown, is designed to be multipole, i.e. it has several switching poles which are arranged next to each other and each has a switching contact, wherein at least one of the two contact pieces of each switching contact is movably mounted in the switch housing 2.

[0024] Each switching contact of the circuit breaker 1 is associated with two electrical terminals, a first terminal 3 and a second terminal 4, which are electrically connected inside the switch housing 2 to one of the two contacts of the respective switching pole. That is, one of the two contacts is electrically connected to the first terminal 3, and the other to the second terminal 4. On the connection side, i.e., on the rear side of the circuit breaker 1, the first terminal 3 and the second terminal 4 extend through the switch housing 2 to the outside, where, during the installation of the circuit breaker 1, they are electrically connected to a conductor (not shown) assigned to the respective terminal, for example, a busbar.In the area of ​​the first connection piece 3, the switch housing 2 has a cover 5 which is attached to the switch housing 2 and which in turn has an opening 6 through which the first connection piece 3 is passed.

[0025] The Fig. 2 and Fig. Figure 3 schematically shows a switching device 10 of the circuit breaker 1 according to the invention in a first switching position in various views. The switching device 10 serves to switch, i.e., to change, the voltage tap between the first terminal 3 and the second terminal 4. Fig. Figure 2 shows a cross-section of the switching device 10, while in Fig. 3 a corresponding sectional view is shown along the section line III-III.

[0026] The Fig. 4 and Fig. 5 show the ones in the Fig. 2 and Fig. 3. The switching device 10 shown in a second switching position is shown in the corresponding views. Fig. Figure 4 shows the elevation of the switching device 10 in the second switching position. Fig. 3 shows - as before Fig. 3 - a corresponding sectional view along the section line VV.

[0027] In the illustrated embodiment, the switching device 10 is mounted on an inner side of the cover 5 facing the circuit breaker 1 and has a linearly movable mechanical switching element 14, which in this case is a slide switch. For actuating the switching device, it has an operating element 15, which is mechanically connected to the switching element 14 and passes through an opening 7 formed in the cover 5, so that it can be manually actuated from an outer side of the cover 5 opposite the inner side. The opening 7 thus serves as a guide for the operating element 15.

[0028] Furthermore, the switching device 10 has a first contact element 11, which can be electrically connected to the first terminal piece 3 via a first guide rail 17, and a second contact element 12, which can be connected to the second terminal piece 4 via a second guide rail 17 (see Fig. 1) is electrically connectable, as well as a third contact element 13, which is electrically connectable to an electronic component (not shown) of the circuit breaker 1. By mounting the cover 5 on the switch housing 2, the electrically conductive connections of the first contact element 11 to the first terminal 3, of the second contact element 12 to the second terminal 4, and of the third contact element 13 to the electronic component are then established.

[0029] On a side facing away from the operating element 15 – facing the inside of the circuit breaker 1 – the mechanical switching element 14 has an electrically conductive sliding surface 16, which serves to connect the third contact element 13 with the first contact element 11 (first switching position, see Fig. 2 and Fig. 3) or the second contact element 12 (second switching position, see Fig. 4 and Fig. 5) to connect electrically.

[0030] The third contact element 13 establishes an electrical connection between the first or second terminal 3 or 4 and the electronics of the circuit breaker 1. The electronics are located in the switch housing 2 of the circuit breaker 1 and primarily serve to implement the tripping function of the circuit breaker 1. The electronics are therefore referred to as the electronic trip unit (ETU). In addition to initiating the tripping of the circuit breaker 1, the ETU can also perform a variety of other functions, such as the acquisition and processing of measurement signals. The electronics thus control the circuit breaker 1.

[0031] During the commissioning of the circuit breaker 1, the responsible technician can position the mechanical switching element 14 by moving the operating element 15 in one direction or the other, so that either the first contact element 11 or the second contact element 12 is electrically connected to the electronics of the switching device 1 via the third contact element 13.

[0032] In the illustrated embodiment, the first contact element 11, the second contact element 12, and the third contact element 13 are designed as leaf spring contacts, establishing an electrically conductive contact with the sliding surface 16 in the respective switching position. The design as leaf spring contacts is only an example; other contacting options are also possible.

[0033] Furthermore, the representations of Fig. 2, Fig. 3, Fig. 4 to Fig.5. The electrical connections of the first contact element 11 to the first terminal 3 and of the second contact element 12 to the second terminal 4 are realized by means of electrical conductors 17. However, this is not mandatory or even essential to the invention: alternative electrical connections, for example other rigid conductors or stranded wires, would also be possible. Reference symbol list 1 circuit breaker 2 switch housings 3 first connecting piece 4 second connector 5 Cover 6 Opening 7 Opening 10 Switching device 11 first contact element 12 second contact element 13 third contact element 14 Switching element 15 Control element 16 Sliding surface 17 Guide rail

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