ELECTRICAL SWITCHING SYSTEM

Abstract

An electrical switching system of a circuit breaker, with a first busbar extending in a longitudinal direction, which carries a first contact and a second contact spaced apart therefrom in the longitudinal direction, and which has a first power connection, and with a second busbar extending in the longitudinal direction, which carries a first counterpart contact and a second counterpart contact spaced apart therefrom in the longitudinal direction, and which has a second power connection. The second busbar is mounted so as to be movable in a transverse direction perpendicular to the longitudinal direction, wherein the first busbar partially overlaps the second busbar along the longitudinal direction. In the longitudinal direction, the contacts and the counterpart contacts are arranged between the two power connections in the overlap region.

Claims

1. An electrical switching system of a circuit breaker, the electrical switching system comprising: a first busbar extending in a longitudinal direction that carries a first contact and a second contact spaced apart from said first contact in the longitudinal direction and a first power connection; a second busbar extending in the longitudinal direction, which carries a first counterpart contact and a second counterpart contact spaced apart from said first counterpart contact in the longitudinal direction; and a second power connection, wherein the second busbar is mounted so as to be movable in a transverse direction substantially perpendicularly to the longitudinal direction, wherein the first busbar partially overlaps the second busbar along the longitudinal direction, and wherein the first and second contacts and the first and second counterpart contacts are arranged in the longitudinal direction between the two power connections in the overlap region.

2. The electrical switching system according to claim 1, wherein the first contact covers the first counterpart contact and the second contact covers the second counterpart contact in the transverse direction.

3. The electrical switching system according to claim 2, wherein the first contact is formed by a cylinder and the first counterpart contact is formed by a spherical segment.

4. The electrical switching system according to claim 1, wherein the first busbar and the second busbar are metal strips.

5. The electrical switching system according to claim 4, wherein the second busbar is arranged substantially perpendicularly to the first busbar.

6. The electrical switching system according to claim 1, wherein between the two counterpart contacts, the second busbar has a projection directed towards the first busbar.

7. The electrical switching system according to claim 1, wherein the first busbar is spring-loaded in the transverse direction.

8. A circuit breaker comprising: an actuating device; and an electrical switching system according to claim 1, wherein the second busbar is actuated by the actuating device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

[0032] FIG. 1 shows a schematic diagram of an industrial plant with a circuit breaker,

[0033] FIG. 2 shows the circuit breaker comprising an electrical switching system in an open state, and

[0034] FIG. 3 shows the circuit breaker in a closed state.

DETAILED DESCRIPTION

[0035] In FIG. 1 a schematic diagram of an industrial plant 2 is shown, which has a power supply 4 and an actuator 6 operated by it. By means of the power supply 4 an electric alternating voltage with 50 Hz or 60 Hz is provided. In particular, the electrical voltage is 277 V or 480 V. The actuator 6 comprises, for example, an electric motor or a press and is electrically coupled to the power supply 4 by means of a line 8, so that the actuator 6 is supplied with current via the line 8.

[0036] Furthermore, the industrial plant 2 comprises a power switch 10, which in one embodiment is a part of the line 8 and is arranged in a control cabinet. In an alternative embodiment, the power switch 10 is arranged on the power supply 4 or on the actuator 6. The power switch 10 has a circuit breaker 12 and an overcurrent protection member 14 connected in series therewith. The electrical series connection is provided in one of the cores of the line 8.

[0037] In this example, the rated current of the power switch 10 is 60 A, and when the rated current is exceeded by more than a certain limit value, for example 1.1 times the rated current, the electric current flow is interrupted by means of the circuit breaker 12. In other words, in this case, the circuit breaker 12 is tripped and thus opened. The overcurrent protection member 14, on the other hand, does not trip in this case. Said overcurrent protection member 14 only trips from five times the rated current, i.e. from 300 A, wherein the tripping time is less than the tripping time of the circuit breaker 12. In this case, the electric current flow is thus interrupted by means of the overcurrent protection member 14, whereas the circuit breaker 12 continues to be in the electrically conductive state. Due to such an interconnection of the circuit breaker 12 and the overcurrent protection member 14, in case of a comparatively small exceeding of the rated current by the electric current, the power switch 10 is substantially immediately ready for operation by resetting the circuit breaker 12. Also, a replacement of components is not required, which reduces operating costs. However, if the overcurrent is comparatively large, in particular greater than 300 A, damage is possible when switching by means of the mechanically equipped circuit breaker 12. In this case, actually an arc occurs, which may cause a damage of components of the circuit breaker 12. Since the circuit breaker 12 is not tripped, it is not damaged, and the power switch 10 is also ready for use again after replacement of the overcurrent protection member 14.

[0038] FIG. 2 shows the circuit breaker 12 in an open state and FIG. 3 shows it in a partially schematic simplified closed state. The circuit breaker 12 has a detection device 16, by means of which the electric current conducted by the circuit breaker 12 is detected. By means of the detection device 16, an actuation device 18 is actuated and consequently driven. The detection device 16 and the actuating device 18 are implemented by means of a common component. In the variant shown, however, these are components separate from each another, and the detection device 16 is a bimetal, by means of which a spring-loaded mechanism is held in a certain position. During operation, the bimetallic latch 16 is traversed by the electric current conducted by means of the circuit breaker 12, and the spring-loaded mechanism is a component of the actuating device 18.

[0039] By means of the actuating device 18, a second busbar 20 is actuated and moved by means thereof in a transverse direction 22, wherein in the closed state and in the open state of the circuit breaker 12, the second busbar 20 is located at two different positions in the transverse direction 22. The second bus bar 20 is a component of an electrical switching system 24, which comprises a guide for the second bus bar 20, so that the second bus bar 20 can be moved in the transverse direction 22. Other movement of the second busbar 20, on the other hand, is prevented due to the guide. In other words, the second busbar 20 is mounted so as to be movable in the transverse direction 22.

[0040] The second bus bar 20 extends in a longitudinal direction 26, which is perpendicular to the transverse direction 22, and the second bus bar 20 is stamped from a metal sheet and is thus designed as a metal strip. The second bus bar 20 is stamped from a copper sheet and is also provided with a silver coating. The metal strip forming the second bus bar 20 is arranged parallel to the transverse direction 22, so that the second bus bar 20 has the smallest extension perpendicular to the transverse direction 22 and perpendicular to the longitudinal direction 26. The second busbar 20 extends substantially in the longitudinal direction 26, where it has the greatest extension.

[0041] A first counterpart contact 28 and a second counterpart contact 30 are connected to the second busbar 20, such as by means of welding, soldering, or riveting. In other words, the second busbar 20 carries the two counterpart contacts 28, 30, and the two counterpart contacts 28, 30 lie on a common straight line extending in the longitudinal direction 26. The two counterpart contacts 28, 30 are identical in construction to each other and are formed by means of a spherical segment. Also, the counterpart contacts 28, 30 are made of a material different from the busbar 20, namely a silver nickel (AgNi). The first counterpart contact 28 is connected in the region of one end of the second busbar 20 in the longitudinal direction 26, and the second counterpart contact 30 is spaced apart from the first counterpart contact 28 in the longitudinal direction 26, there being a distance of 2 cm between them. Furthermore, the second bus bar 20 has a second power connection 32 formed by means of the end of the second bus bar 20 opposite the first counterpart contact 28 in the longitudinal direction 26.

[0042] The electrical switching system 24 further comprises a first bus bar 34 made of the same material as the second bus bar 20. In other words, the first bus bar 34 is also a metal strip stamped from a copper sheet and provided by means of a nickel coating. The first bus bar 34 is oriented perpendicularly to the transverse direction 22, and thus extends mainly in the longitudinal direction 26 as well as transversely to the transverse direction 22. Consequently, the second bus bar 20 is arranged perpendicularly to the first bus bar 34. The first busbar 34 carries a first contact 36 and a second contact 38, which are identical in construction to each other. The contacts 36, 38 are cylindrical in shape and thus formed by means of a cylinder. Also, the contacts 36, 38 are made of the same material as the counterpart contacts 28, 30, namely silver nickel (AgNi).

[0043] The two contacts 36, 38 lie on a common straight line extending in the longitudinal direction 26 and are arranged congruently with the counterpart contacts 28, 30. In this context, the first contact 36 is associated in the first counterpart contact 28 and the second contact 38 is associated in the second counterpart contact 30. Consequently, when the second busbar 20 is moved in the transverse direction 22 towards the first busbar 34, the first counterpart contact 28 is brought against the first contact 36 and the second counterpart contact 30 is brought against the second contact 38, so that they are in direct mechanical contact with each other. In summary, the first contact 36 overlaps the first counterpart contact 28, and the second contact 38 overlaps the second counterpart contact 30 in the transverse direction 22. In other words, the contacts 36, 38 and the respective counterpart contacts 28, 30 are arranged parallel to and directly above each other. Consequently, the two contacts 36, 38 are also spaced apart from each other in the longitudinal direction 26, namely by 2 cm, wherein the second contact 38 is connected to one end of the first busbar 34 in the longitudinal direction.

[0044] Consequently, the two busbars 20, 34 overlap in the longitudinal direction 26 to form an overlap region 40. In this case, the first bus bar 34 overlaps the overlap region 40 on one side of the overlap region 40 in the longitudinal direction 26 and the second bus bar 20 overlaps the overlap region 40 on the opposite side in the longitudinal direction 26. The overlap region 40 is thus substantially equal to 2 cm plus the extent of the counterpart contacts 28, 30 or the contacts 36, 38 in the longitudinal direction 26.

[0045] The first bus bar 34 has a first power connection 42 forming the end of the first bus bar 34 opposite the second contact 38. Consequently, the first power connection 42, as well as the second power connection 32, is arranged outside the overlap region 40. Thus, the contacts 36, 38 as well as the counterpart contacts 28, 30 are arranged in the longitudinal direction 26 between the two power connections 32, 42 in the overlap region 40.

[0046] Furthermore, the electrical switching system 24 has two springs 44 that are spaced apart from each other in the longitudinal direction 26 and oriented in the transverse direction 22. The two springs 44 are supported on a housing and the first bus bar 34, such that the first bus bar 34 is spring-loaded in the transverse direction 22.

[0047] During operation of circuit breaker 12, the two power connections 32, 42 are connected to other components of the power switch 10. To conduct current by means of the circuit breaker 12, the electrical switching system 24 is put in the electrically conductive state. For this purpose, the second busbar 20 is moved in the transverse direction 22, so that the counterpart contacts 28, 30 press against the contacts 36, 38. In particular, the second busbar 20 is locked in the position shown in FIG. 3 by means of the actuating device 28. In this case, the force applied to the second busbar 20 by means of the actuation device 18 is such that the first busbar 34 is also moved in the transverse direction 22 and the springs 44 are compressed. As a result, a force-fit contact is implemented between the contacts 36, 38 as well as the corresponding counterpart contacts 28, 30. As a result, the electric current can flow via the first power connection 42 into the first busbar 34 and there partially via the first contact 36 as well as the first counterpart contact 28 into the second busbar 20. Another part of the electric current is introduced into the second busbar 20 via the second contact 38 as well as the second counterpart contact 30. The electric current is conducted out of the second busbar 20 via the second power connection 32.

[0048] As a consequence thereof, the electric current flows in parallel in the transverse direction 22 in the two contacts 36, 38 and the associated counterpart contacts 28, 30. Furthermore, the electric current flows in parallel in the longitudinal direction 26 in the two busbars 20, 34 in the overlap region 40. Thus, a rectified magnetic field is formed in each of the two busbars 20, 34 in the overlap region 40, which presses the two busbars 20, 34 towards each other in the overlap region 40. To enhance this effect, the second bus bar 20 has a projection 46 directed towards the first bus bar 34 in the overlap region 40 between the two counterpart contacts 28, 30. The projection 46 forms an end at the second busbar 20 in the transverse direction 22, so that the counterpart contacts 28, 30 are recessed in the transverse direction 22 with respect to the projection 46. However, the projection 46 is spaced apart from the first busbar 34, which is why a jumping over of the electric current from the first busbar 34 directly onto the second busbar 20, in particular the projection 46, is avoided. The force pushing the two bus bars 20, 34 towards each other increases with increasing electric current and counteracts any force pushing the bus bars 20, 34 apart in the transverse direction 22. One such force in particular a magnetic force caused due to the electric current flowing in the transverse direction 22.

[0049] Due to the at least partial compensation of the force pushing the two busbars 20, 34 apart, the busbars 20, 34 are not pushed apart in an uncontrolled manner even in the case of a comparatively large electric current, which could lead to a burn-off of the contacts 36, 38 and the counterpart contacts 28, 30 and a partially melting of these. If actually the partially melted contacts 36, 38 or respectively the counterpart contacts 28, 30 would be placed on top of each other again, they would fuse, which is why it would not be possible to move the second busbar 20 in the transverse direction 22 again. Therefore, in the event of such a large electric current, which is at least five times the rated current, the overcurrent protection member 14 is tripped, which is why the electric current is cut off. In this case, however, the electrical switching system 24 continues to be in the electrically conductive state.

[0050] If, by contrast, a comparatively small overcurrent occurs, this is detected accordingly by means of the detection device 16. As a result, the actuating device 18 is actuated and consequently the second bus bar 20 is lifted in the transverse direction 22 from the first bus bar 34. Therefore, an electric current flow between the first and second power connections 42, 32 is interrupted. In this case, the switched electric current is comparatively low, so that damage to the contacts 36, 38 and the counterpart contacts 28, 30 does not occur.

[0051] The invention is not limited to the above-described embodiment example. Rather, other variants of the invention can also be derived therefrom by the expert without leaving the object of the invention. Furthermore, in particular, all individual features described in connection with the embodiment examples can also be combined with each other in other ways without leaving the object of the invention.