Switching device

In a switching device with at least one first electrical switching device input and at least one first electrical switching device output and at least one second electrical switching device output, wherein in a first operating state of the switching device the first switching device input is electrically connected with the first switching device output, wherein in a second operating state of the switching device the first switching device input is electrically connected with the second switching device output, is proposed to configure the switching device for uninterrupted switchover from the first operating state to the second operating state and/or from the second operating state to the first operating state to allow functional testing of a fault current circuit breaker without interruption.

This application also claims the priority of Austrian Patent Application, Serial No. A 1391/2010, filed Aug. 19, 2010, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein.

BACKGROUND OF THE INVENTION

The present invention relates to a switching device and to a fault current circuit breaker. The present invention also relates to a method for functional testing of a first fault current circuit breaker without interruption of the power supply to a connected load.

Fault current circuit breakers have a testing device for testing the functionality of the respective fault current circuit breaker, i.e. triggering, in the event of a fault current. Because the respective fault current circuit breaker is triggered, the downstream partial networks and hence also all connected electrical devices are switched off. This is viewed by most uses of electrical systems as inconvenient, because individual settings are erased in many devices. Moreover, severe problems in many electrical systems may occur when they are switched off, because these electrical systems perform safety-related tasks or control technical processes, so that switching these systems off can lead to problems.

In switching processes where a load current is switched from one fault current circuit breaker to another fault current circuit breaker, a temporary presence of asymmetric potentials on at least one of the two fault current circuit breakers cannot be excluded. Such differences in the potential, however, can act on a fault current circuit breaker like an actually present fault current and thus accidentally trigger the fault current circuit breaker without the presence of a fault current. This may possibly prevent uninterrupted switching from one fault current circuit breaker to another fault current circuit breaker.

It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide an improved switching device which supports functional testing of a fault current circuit breaker without requiring disconnection from the power grid.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a switching device with two operating states includes at least one first electrical switching device input, at least one first electrical switching device output, and at least one second electrical switching device output. In a first operating state of the switching device the first switching device input is electrically connected with the first switching device output, and in a second operating state of the switching device the first switching device input is electrically connected with the second switching device output. The switching device is constructed for uninterrupted transition from the first operating state to the second operating state or from the second operating state to the first operating state.

Such switching device offers the possibility to connect two fault current circuit breakers in parallel and to switch over a load current for one of the two fault current circuit breakers to the other fault current circuit breaker, without triggering one of the two fault current circuit breakers and consequently causing disconnection of the power grid. In this way, the fault circuit current breakers can be functionally tested without causing the loss of settings at electrical devices or safety risks due to importance of the disconnected devices. A fault current circuit breaker identified as being defective can then be exchanged, without requiring disconnection of the electrical partial network connected downstream of the fault current circuit breaker.

This can prevent accidental triggering of one of the two fault current circuit breakers during an intentional uninterrupted switching operation of a load current from a first fault current circuit breaker to a second fault current circuit breaker. Faulty triggering during the switching process can thus be prevented. Unintentional disconnection from the power grid during functional testing of a fault current circuit breaker can then be prevented.

According to another aspect of the present invention, a fault current circuit breaker includes disconnect contacts, and a trigger current circuit at least indirectly operatively connected with the disconnect contacts for disconnecting the disconnect contacts, wherein the trigger current circuit included a first switching arrangement for extending a trigger time of the trigger current circuit by a predetermined time.

In switching processes where a load current is switched from one fault current circuit breaker to another fault current circuit breaker, a temporary presence of asymmetric potentials on at least one of the two fault current circuit breakers cannot be excluded. Such differences in the potential, however, can act on a fault current circuit breaker like an actually present fault current and thus accidentally trigger the fault current circuit breaker without the presence of a fault current. This may possibly prevent uninterrupted switching from one fault current circuit breaker to another fault current circuit breaker.

According to yet another aspect of the present invention, a method for uninterrupted functional testing of a first fault current circuit breaker includes the steps of routing a load current through the first fault current circuit breaker, connecting an input of a second fault current circuit breaker to the load current in parallel with the first fault current circuit breaker, switching the load current over without interruption from the first fault current circuit breaker to the second fault current circuit breaker, performing a functional test of the first fault current circuit breaker, after a successful functional test of the first fault current circuit breaker switching the first fault current circuit breaker on, connecting an input of the first fault current circuit breaker to the load current in parallel with the second fault current circuit breaker, and switching the load current over without interruption from the second fault current circuit breaker to the first fault current circuit breaker.

A functional test can then be performed on a fault current circuit breaker without disconnection from the power grid. The functional testing can then be also performed on fault current circuit breakers without a loss of settings on electrical devices or without causing safety risks due to disconnection of important devices.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Turning now to the drawing,FIGS. 1 to 6show each an arrangement of a first fault current circuit breaker22, a second fault current circuit breaker23and a switching device1according to the invention, wherein the first fault current circuit breaker22and the second fault current circuit breaker23are electrically connected in parallel with the switching device1by way of a coupling unit.

The present invention relates to a method for uninterrupted functional testing of at least one fault current circuit breaker22, as well as devices for advantageously performing the method. Preferred embodiments of the respective devices will be described below, wherein the method according to the invention described below is preferably not necessarily tied to the use of the described devices.

The disclosed devices include preferred embodiments of a fault current circuit breaker22,23according to the invention, a special switching device1according to the invention, and a coupling device12for at least electrically and additionally particularly mechanically connecting two fault current circuit breakers with the switching device.

FIGS. 1 to 3each show, inter alia, a schematic circuit diagram of a different preferred embodiment of a switching device1with at least one first electrical switching device input2, and at least one first electrical switching device output3and at least one second electrical switching device output4, wherein in a first operating state of the switching device1the first switching device input2is electrically connected with the first switching device output3, wherein in a second operating state of the switching device1the first switching device input2is electrically connected with the second switching device output4, wherein the switching device1is configured for an uninterrupted transition from the first operating state into the second operating state and/or from the second operating state into the first operating state.

With this type of switching device1, two fault current circuit breakers22,23can be connected in parallel and a load current can be switched from one of the two fault current circuit breakers22,23to the other fault current circuit breaker23,22, without triggering one of the two fault current circuit breakers22,23, which would cause disconnection from the power grid. The functional test of fault current circuit breakers22,23can then be performed without a loss of settings on electrical devices or causing safety risks due to an unplanned disconnection of important electrical devices. A fault current circuit breaker22identified as being defective can also be interchanged without necessitating disconnection of the electrical partial grid connected downstream of the fault current circuit breaker22,23, because the respective other fault current circuit breaker23protects during the switchover the downstream connected electrical grid and the connected users.

The term “uninterrupted” preferably indicates a switchover of a load current from one switching device, in the present example from the first fault current circuit breaker22, to another switching device, in the present example to the second fault current circuit breaker23, without causing interruptions of the power supplied to downstream components, either due to brief disruptions of the grid during the switching process itself or due to accidental triggering of at least one of the fault current circuit breakers22,23.

According to the invention, the switching device1can assume a first and a second operating state. Preferably, the switching device1has only these two stable operating states, and the transition from one of these operating states to the respective other operating state is implemented as a brief switching process, which itself is not viewed as a stable operating state.

In a modification of the invention, the switching device1may further have a third operating state, where the first switching device input2is electrically connected with the first switching device output3and with a second switching device output4, and the transitions from the first or second operating state to the third operating state and from the third operating state to the first or second operating state are also implemented to be uninterrupted. This approach not only allows a load current to be switched uninterruptedly from a first fault current circuit breaker22to a second fault current circuit breaker23and vice versa, but also enables a stable parallel operation of the to fault current circuit breakers22,23.

The switching device1has, as mentioned above, at least one first electrical switching device input2and at least one first electrical switching device output3and at least one second electrical switching device output4. The terms input and output should be interpreted so that the terms which are used in the singular preferably include all functionally required connections of an input and output2,3,4. In the illustrated preferred embodiments, the first switching device input2has two terminals, and the first end second switching device outputs3,4likewise have two terminals. Preferably, a switching device output2has the same number of terminals as each of the switching device outputs3,4, commensurate with the number of conductors, such as the phases and the neutral conductor, of the electrical grid to be protected or to be switched.

The switching device1has preferably at least one switch5,7which is electrically connected with the first control device input2, the first control device output3and the second control device output4, wherein in a first switch position of the switch5,7the first control device input2is electrically connected with the first control device output3, and wherein in a second switch position of the switch5,7the first control device input3is electrically connected with the second control device output4. The respective switch5,7is hereby constructed so that the transition from the first switch position into the second switch position is made without interruption. The switch5,7may only have the two aforedescribed stable switching states. In addition—if the switching device1is designed with the aforedescribed third operating state—a corresponding third switch position, for example in form of a center position of the switch5,7, can be implemented.

According to the embodiments illustrated inFIGS. 1 and 2, the switching device1preferably has at least one mechanical switch5with at least partially overlapping switching contacts6. This is indicated in the corresponding Figures by the symbolic diagram of the mechanical switch5. A switching device1which is unaffected by electrical disturbances and which can be easily maintained even under severe conditions can be implemented with such mechanical switch5.

Preferably, the contacts also mechanical switch5are connected to and guided by a switch shaft. Moreover, the mechanical switch can preferably be connected with a switch lock. The switching process of the respective mechanical switch5can then be predefined and force-actuated.

According to the embodiment illustrated inFIG. 3, the switching device1preferably includes an electronic switch7. In this way, a switching device1can be constructed which is substantially unaffected by mechanical vibrations and allows fast switching processes.

As illustrated inFIG. 3, the respective electronic switch7is preferably formed as a switching arrangement having a predetermined number of triacs8. Triac8is here an abbreviation for “triode alternating current switch.” However, the switching arrangement may include any type of switch, such as semiconductors, whereby the switching element may be implemented particularly in form of a transistor or include a transistor.

Preferably, the switching device1includes at least one control device9for controlling the transitions from one operating state to another operating state. With such control device9, the switching process can be actively performed and monitored. For example, it can be monitored that the full grid voltage is already present at the second fault current circuit breaker23, before the first fault current circuit breaker22is switched off, i.e. having its input disconnected from the power grid.

The control device9is preferably constructed as or includes a programmable logic circuit and/or a microprocessor. Additionally, the switching device1may preferably include a power supply, which is not illustrated in the figures, for supplying electrical energy to the control device9.

According to the illustrated preferred embodiments of a switching device according to the invention, which all include a control device9, the mechanical or electronic switch5,7may be controlled by the control device9and operationally connected with the control device9. For example, the control device may act on the switch lock, at least indirectly, by way of an electromechanical actuator; or the switch5,7may be implemented as an electronic switch7controlling the gate terminal of the illustrated triac. Alternatively, the mechanical switch5may be part of a relay arranged in the switching device and controlled by the control device.

According to another illustrated preferred embodiment, the switching device1may include at least one voltage measuring device for measuring a voltage on the first switching device output3and/or the second switching device output4. In this way, it can be ensured that the full grid voltage is present at the second fault current circuit breaker23before the first fault current circuit breaker22is switched off. In this context, the voltage measuring device is preferably constructed as part of the control device9, and the control device9is electrically connected with the first switching device output3and/or the second switching device output4.

Preferably, the switching device has at least one actuating element25which is operatively connected with the control device9(if a control device is provided), wherein—for example, when simple switching devices1are used—the actuating element25may be implemented as a manual actuating element of the switch5embodied as a mechanical switch5. Preferably, and as illustrated, the actuating element25may be connected with and acting upon the control device9.

In addition, according to a preferred embodiment of a switching device1according to the invention, the switching device1may include at least one, in particular optical, signaling means11which is controlled in particular by the control device9. In this way, the operating state of the switching device1and/or of the fault current circuit breakers22,23connected with the switching device1can be indicated. In this way, a command for unblocking or operating the testing device of one of the two fault current circuit breakers22,23can be communicated to a user. In the illustrated embodiment, the switching device1includes two signaling means11implemented as LEDs. It should be mentioned that the electrical connections between the control device9and the signaling means are not shown inFIGS. 1 to 3.

FIG. 1shows a first preferred embodiment composed of a switching device1according to the invention, a first and a second fault current circuit breaker22,23. An unillustrated power grid is connected to the first electrical switching device input2. An input of the first fault current circuit breaker22is electrically connected with the first switching device output3, and an input of the second fault current circuit breaker23is connected with the second switching device output4.

The switching device1has a mechanical switch which is controlled by the control device5.

According toFIG. 1, the first and the second fault current circuit breakers22,23are constructed as grid-voltage-independent fault current circuit breakers, with each including a sum current converter32, a permanent magnet trigger31, and a trigger circuit19and a switch lock26controlling a switch shaft on which break contacts20are arranged.FIGS. 1 to 3do not show the details of the trigger circuit19and hence also not the details of the components or assemblies of this trigger circuit19. Furthermore, the two fault current circuit breakers22,23each have a test circuit30with a test button27and a test resistor28. When the context of the test button27are closed, the test circuit connects the two conductors of the grid to be protected, which is routed through the fault current circuit breaker22,23, bypassing the sum current converter32, and thereby stimulating a fault current. Other embodiments different from the illustrated embodiments may also be contemplated.

The two fault current circuit breakers22,23illustrated inFIG. 1are preferably equipped with a delayed fault current trigger. In the event of a fault current, such fault current circuit breakers22,23are not immediately triggered, but are triggered only when the fault current is still present after a predetermined time. Such fault current circuit breakers22,23are also referred to as G-type or S-type.

In an arrangement according toFIG. 1, uninterrupted switching of the load current from the first to the second fault current circuit breaker22,23is possible without causing triggering, as long as the switching process takes place in a shorter time duration than the planned duration of the trigger delay of the two fault current circuit breakers22,23. Any asymmetric potentials occurring during the switching process are not misinterpreted as a fault current, because they occur only during a very brief time during which fault current triggering does not occur.

FIGS. 2 and 3show additional embodiments of arrangements according to the invention.

The basic structure of an arrangement according toFIG. 2is mostly identical to a structure according toFIG. 1, with the arrangement ofFIG. 2having additional assemblies.

The two fault current circuit breakers22,23according toFIG. 2are—although not directly evident from FIG.2—constructed without a trigger delay or delay-free, and therefore trigger as quickly as possible when a fault current is detected. To allow an uninterrupted switchover with such fault current circuit breakers22,23, the switching device1has preferably a first control output10for affecting the trigger characteristic of a fault current circuit breaker22,23in a predetermined manner.

The trigger current circuit19of the first and the second fault current circuit breaker22,23according toFIG. 2has furthermore a first circuit arrangement21, for prolonging a trigger time of the trigger current circuit19by a predetermined time.

The first switching arrangement21may be configured differently, depending on the design of the trigger circuit. In the present example, the first switching arrangement21may be configured for short-circuiting the connection between a secondary winding of the sum current converter32and the permanent magnet trigger31. However, other actuating mechanisms and circuit arrangements may also be contemplated.

According to the illustrated embodiment of a fault current circuit breaker22,23, the fault current circuit breaker22,23has at least one first control input24for controlling the first switching arrangement21.

Depending on the type of control of the first switching arrangement21, a control may be separate from the switching device1according to the invention, wherein the switching device1preferably has at least one first control output10for affecting the trigger characteristic of a fault current circuit breaker22,23, which is preferably electrically connected with the control device9, in a predetermined manner.

As illustrated inFIG. 2, the switching device1has a first control output10and a second control output, wherein the first control output10is electrically connected with the first control input24of the first fault current circuit breaker22, and the second control output is connected with the first control input24of the second fault current circuit breaker23.FIG. 6shows a structural embodiment of such arrangement in an exploded view.

Alternatively, one of the fault current circuit breakers22,23may be constructed as fault current circuit breaker with delayed fault current triggering, while the other fault current circuit breaker23,22may be constructed as fault current circuit breaker22,23according to the invention without a delay.

FIG. 3shows a third preferred embodiment of an arrangement of a switching device1according to the invention and two fault current circuit breakers22,23, wherein the two fault current circuit breakers22,23are constructed as fault current circuit breakers with delayed fault current triggering, and wherein the switch of the switching device1is implemented as an electronic switch7including four triacs, which are each controlled by the control device9.

Preferably, the switching device1, like the fault current circuit breakers22,23, has a housing made of an insulating material.

The two fault current circuit breakers22,23and the switching device may be electrically connected, for example, with wire jumpers. Because this is complicated and error-prone, the respective components may be more particularly connected by a coupling device12for electrical switching devices. Such coupling devices12for electrical switching devices1are illustrated, for example inFIGS. 4 to 6, which illustrate preferred embodiments of arrangements according to the invention.

A preferred coupling device12for electrical switching devices has at least one first input13and at least one first output14, wherein the first input13is electrically connected with the first output14, wherein the coupling device12has at least one second input15and at least one second output16, wherein the second input15is electrically connected with the second output16, wherein the coupling device12has at least one third input17and at least one third output18, wherein the third input17is electrically connected with the third output18.

Preferably, the at least one first input13is constructed to include at least one screw terminal, and/or the at least one second and/or third input15,17and/or the at least one first and/or second and/or third output14,16,18are constructed as plug contacts.

The embodiment of a coupling device12according toFIGS. 5 and 6is implemented in the aforedescribed manner, wherein the respective embodiment further includes the corresponding contacts and connecting lines for connecting the first control outputs of the switching device1with the corresponding24of the first and second fault current circuit breaker22,23.

The arrangement according toFIG. 4has a structure which is different from the other structural embodiments of the invention. This arrangement does not include a switching device1, but only a control device40. Preferably, such control device40is constructed according to the preferred embodiments of a switching device1according to the invention, wherein the control device40itself does not include a switch, but rather only the electrical interfaces required for controlling an external switch.

The arrangement according toFIG. 4has furthermore a specially designed coupling/switching device41which includes a switch. This coupling/switching device41includes the corresponding feed lines for the wiring of the electrical power grid, as well as corresponding outputs for controlling the first and/or second fault current circuit breakers22,23. The coupling/switching device41also includes a switch which is formed according to the preceding description of switches in a switching device1according to the invention and which therefore allows an uninterrupted switchover of the load current from one of the two fault current circuit breakers to the other. In addition, the coupling/switching device41includes an interface for receiving switching commands from the control device40.

The present invention furthermore relates to a method for uninterrupted functional testing of a first fault current circuit breaker22, wherein a load current flows through the first fault current circuit breaker22, wherein the input side of a second fault current circuit breaker23is connected in parallel with the first fault current circuit breaker22to the load current, wherein the load current is uninterruptedly switched from the first fault current circuit breaker22to the second fault current breaker23, wherein a functional test of the first fault current circuit breaker22is performed, wherein after the first fault current circuit breaker22has been successfully functionally tested, the first fault current circuit breaker22is switched on, wherein the input side of the first fault current circuit breaker22is connected in parallel with the second fault current circuit breaker23to the load current, wherein the load current is switched without interruption from the second fault current circuit breaker23to the first fault current circuit breaker22, and wherein the second fault current circuit breaker23is switched off.

This method can be used to test the functionality of a fault current circuit breaker22,23without interruption.

The process flow of a particular embodiment of a method according to the invention will now be described, wherein not all the described preferred process steps must be necessarily executed.

After the load current preferably flows through the coupling device12, the load current flows through the switching device1, as well as through the first fault current circuit breaker22to a consumer. The second fault current circuit breaker23is electrically connected in parallel to the first fault current circuit breaker22, wherein the second fault current circuit breaker23is switched on at this time, with the disconnect contacts20closed, but is on the input side not connected to the power grid. Accordingly, no current flows at this time via the second fault current circuit breaker23to the consumer.

However, the output or load side of the second fault current circuit breaker23is connected with the corresponding terminals of the first fault current circuit breaker22, causing its testing device to be essentially at the same electrical potential as the corresponding devices of the first fault current circuit breaker22. According to a preferred embodiment of the method of the invention, a corresponding functional test of the second fault current circuit breaker23is performed, preferably by operating the test button27of the second fault current circuit breaker23, before the functionality of the fault current triggering of the first fault current circuit breaker22is further tested.

For uninterrupted testing, the input side of the second fault current circuit breaker23is connected by the switching device1in parallel with the first fault current circuit breaker22to the power supply grid. In this situation, the load current flows to a load via both the first and the second fault current circuit breakers22,23, if such load is operated at that time.

Preferably, before the uninterrupted switchover from the first fault current circuit breaker22to the second fault current circuit breaker23, it is checked if the second fault current circuit breaker23is switched on. In this way, the first fault current circuit breaker23can be prevented from switching off, as long as the second fault current circuit breaker23is not yet ready to carry the load current.

Optionally, the trigger circuits19of the first and the second fault current circuit breaker22,23may be inhibited, or a first trigger time of the first fault current circuit breaker22and a second trigger time of the second fault current circuit breaker23may be extended for a predetermined time during the uninterrupted switchover from the first fault current circuit breaker22to the second fault current circuit breaker23. Completely inhibiting triggering may also represent an extension of the trigger time.

Thereafter, the load current is switched without interruption from the first to the second fault current circuit breaker and the first fault current circuit breaker22is then disconnected from the load current, wherein this switchover process is preferably performed with the switching device according to the invention. The first fault current circuit breaker22is still connected on the load side with the second fault current circuit breaker23.

If the trigger circuits of the first and the second fault current circuit breakers22,23were inhibited, this inhibit is canceled.

Preferably, a first signal, in particular an optical signal, is outputted after the uninterrupted switchover from the first fault current circuit breaker22to the second fault current circuit breaker23. This signal informs the user that the first fault current circuit breaker22can be checked to test the functionality of the fault current triggering. Preferably, other operating states or instructions, for example relating to the actuation of the testing device of a particular fault current circuit breaker, may be displayed to the user.

The functionality of the fault current triggering of the first fault current circuit breaker22can then be tested. To this end, the test button27of the first fault current circuit breaker22is actuated, which can be done manually, or—if implemented as an electrical circuit—with a remote signal control of the test button27, for example by the switching device1. Because of the first fault current circuit breaker22is connected on the load side with a second fault current circuit breaker23, a conventional test circuit30continues to function.

After successful testing the functionality of the fault current triggering of the first fault current circuit breaker22, i.e., if the first fault current circuit breaker22was triggered successfully, a switchover occurs from the second fault current circuit breaker23to the first fault current circuit breaker22. The first fault current circuit breaker22is then again switched on, at a first step. The input side of the first fault current circuit breaker22is then once more connected in parallel with the second fault current circuit breaker23to the load current, and the input side of the second fault current circuit breaker23is then disconnected from the load current.

In this state, testing of the fault current triggering of the second fault current circuit breaker23is planned, unless not previously performed, for example by actuating the corresponding test current circuit30of the second fault current circuit breaker23.

When testing or using fault current circuit breakers22,23having delayed fault current triggering, only the aforedescribed method steps are preferably implemented.

When testing or using fault current circuit breakers22,23which do not have a corresponding delay of the fault current triggering, then the trigger time of the corresponding fault current circuit breakers22,23is preferably extended and/or the triggering is completely inhibited during switchover from one fault current circuit breaker22,23to the other fault current circuit breaker23,22—as already described above.