DE19850397A1 - Electrical residual current circuit breaker - Google Patents

Abstract

The invention relates to a novel residual-current protective switching device. The switch or switches (1, 1') have at least one respective microrelay (3) for the interruption of current or currents in monitored current paths (8, 8').

Description

This invention relates to an electrical switching device for residual current protection.

Conventional two-pole residual current circuit breakers ("FI switches") exist in the essentially from an induction coil for detecting a current asymmetry between z. B. a phase conductor and a neutral conductor of a household power supply care. The currents in the conductors are taken into account Direction added. If the sum is clearly different from zero, i. H. about a certain threshold is a conventional electromagnetic Relay switch triggered. In this case it must be assumed be that the fault current above the threshold is caused by an un permissible short circuit, earth contact or leakage current.

The invention is based on the technical problem, a new improved Residual current switchgear to be specified.

According to the invention, this problem is solved on the one hand by an electrical one Residual current protection switching device with a first micro relay switch in egg nem first current path and an evaluation device for receiving and off evaluating signals from a sensor that detects the current through the first current path first current sensor and a current through a second current path second current sensor by comparison with each other and opening the first micro relay switch in response to a result of the evaluation, and on the other hand by an electrical residual current protection switching device with egg a first micro relay switch in a first circuit and a Ge total current through the first current path and at least a second adjacent the first total current sensor and an evaluation direction for receiving and evaluating a signal of the first total current  sensors and opening the first micro relay switch in response to a result the evaluation.

Embodiments of the invention are the various dependent claims refer to.

The invention is based on the basic idea that the use of microrelay scarf tern in a residual current circuit breaker various essential Vor brings with it. A micro relay as such is state of the art. Here han it is an electrically operated miniature switch, but in the opposite Set a transistor with a mechanical switch with at least one moving union contact. The mechanical movement of this contact caused by an electrical signal. Come for implementation different mechanisms in question. Electrics are particularly preferred here trostatically operated microrelay cells. However, it can also be electromagnetic Devices are used which generally have planar spiral coils can be used with ferromagnetic movable contact pieces. Pie too zoelectric micro relays are possible, but require high control voltages gene.

As a concrete example of a possible technology for electrostatic actuation Microrelay cell is referenced to one published by Siemens Si microrelays (H.F. Schlaak, F. Arndt, J. Schimkat, M. Hanke, Proc. Micro System Technology 96, 1996, pages 463-468). Please also refer to R. Allen: "Simplified Process is Used to Make Micromachined FET-like Four-Terminal Microswitches and Microrelays "in Electronic Design, 8 July, 1996, page 31 as well on "Micromechanic Membrane Switches on Silicon" by K.E. Petersen, IBM J. RES. DEVELOP., Vol. 23, No. 4, July 1979, pages 376-385. The revelation content of this and the sources cited below is in this application included.

In this invention, the term microrelay switch now denotes both a single micro relay existing switching devices as well as switching devices  directions that contain two or more microrelays. This will be followed in the following referred to again.

Going back to the advantages of micro relay switches mentioned are first significantly faster switching times in the range of, for example, 100-200 µs possible instead of the reaction times of conventional residual current circuit breakers of over 25 ms. Especially considering the safety function of errors Current protection switching devices, this aspect is of great importance.

Furthermore, the microrelay switches can be compared to conventional ones Electromagnetically operated relays with extremely low component weight realizing volumes and volumes. In this respect, they are suitable for installation in techni environments where a conventional residual current circuit breaker either lead to a significant increase in weight or volume would or could not be used in principle. An example are smaller elec tronic devices, connectors z. B. on cables, standard housing for Connector sockets z. B. for wall mounting etc.

In this connection it should finally be mentioned that micro relay switches due to the usable mass production technologies from the Be a large series production with very low unit cost Allow.

The first of the above two definitions of the invention now uses at least a microrelay switch which is responsive to the signals of at least two Current sensors is operated. Each current sensor detects the current through a respective current path, such as a cable or a conductor track. The evaluations device compares the signals with each other and can be checked by one Mismatch between the individual signals the occurrence of a fault current to capture. Accordingly, the result of this evaluation is crucial bend for controlling the micro relay switch.  

A total current sensor was mentioned in the second definition of the invention, which the current through a first current path together with the current through the second current path detected. It is thought of a current sensor due to of the spatial conditions, the sum suitable for residual current detection from both streams taking into account their directions. For example You can use two conductor tracks as current paths to compare the currents in lead opposite directions, the total current sensor the total current is recorded, in the case of an equal amount, a zero current. Accordingly, the signal of the total current sensor has to go through the evaluations device only compared with a correspondingly small threshold to control the micro relay switch.

It is of course also possible that the total current sensor the currents through the both (or more) current paths do not have the same sensitivity recorded, but for example due to certain spatial conditions Amount identity of the currents does not provide a zero signal. Then the evaluation can be direction can of course also be designed to signal the total current sensor to relate to a certain target range that is not related to the value Is centered zero.

Of course, the two variants of the invention can also be used in different ways be combined.

One embodiment of the invention relates to a residual current circuit breaker device for three-phase lines with neutral, in which a fault current is to be determined with reference to the adjustment in four current paths. You can do this According to the invention, four current sensors are provided for each current path be, whose signals are evaluated by the evaluation device.

Also in addition to a Ge measuring the currents through two current paths The total current sensor can be a third and a fourth current sensor or a second Total current sensor can be provided for the third and fourth current path.  

The evaluation device is preferably implemented in a microelectronic manner Circuit that the expert with regard to the task without further ado it's clear.

With the current sensors, it should first be noted that they are not necessarily Be part of the residual current protection switching device according to the invention have to. It can also be conventional current sensors, for example act wise induction coils. In view of the possible with the invention Advantages relates to the most advantageous choice, however, Hall sensors that work as a half lead terelemente also be comparatively small, light and inexpensive can. In particular, Hall sensors also have very low detection limits zen realizable, for example in the range of about 1 mA compared to one conventional detection limit of about 10 mA or above.

So far, the invention in connection with a micro relay switch in described one of the current paths. Of course, two or more can also be used Microrelay switches can be used to allow some or all of the detection affected current paths can be switched. In the case of he already mentioned three-phase lines with neutral conductor, it is of interest, for example, switch off all four poles when detecting a fault current. Even in the case of one Line with one phase and one neutral can be beneficial, both lei interruptions. For example, this frees you from the need for Installation to ensure that the phase and neutral conductor do not come together at any point swap. This is particularly advantageous in the area of plug connections, because they are often symmetrical and, in this respect, they are mixed up of neutral conductor and phase can be inserted. In particular, exist also safety regulations for RCDs, which require all poles to be switched off gene.

It has already been pointed out that the term microrelay switch in a general sense is used that includes both a single microrelay and  also includes a switching device consisting of two or more microrelays. In order to the fact that microrelays are technology-related is taken into account certain limits with regard to their current carrying capacity and dielectric strength are subject. If the current carrying capacity or the dielectric strength of the individual micro relay envisaged for the intended application not sufficient, it is provided according to the invention, voltage-dividing series Circuit consisting of two or more microrelay cells and / or current-dividing par to use allel circuits. Panels in the sense of span power-sharing series circuits of current in each stage of the series circuit dividing parallel circuits are used. That aspect becomes referred to the pre-registration filed on 10/10/1998 "New electrical Switching device "from the same applicant with the file number 198 46 639.0, de revelation content is in process here.

However, there are technological trends at the time of filing this invention zen for the execution of individual micro relays with quite high voltage and current tolerances known. This means that there will be further improvements in the future foreseeable. For example, a research project of the manufacturer is concerned Bosch with the University of Bremen with the development of micro relay with 24 V maximum switching voltage and 25 A maximum switching current. Out the numerical values mentioned can be seen that especially with one The current carrying capacity of the microrelay for many applications, for example is to be expected with household electricity networks. Then an appropriate Seri is sufficient Circuit for adaptation to the respective voltage specification.

It is particularly advantageous to have different micro relay switches in one established standard technology and accordingly unchanged Standard micro relay cell in different sizes of parallel connection, Seri circuit or the control panel. All that is required is the geome the layout can be changed, for example by exchanging the masks sentence. Otherwise, the manufacturing process is practically unchanged. Here This results in the cost advantages of a large size being largely retained  Series production Different ways of covering a large area most electrical specifications. This also applies to the case of individuals Micro relay switch as well as in an integrated combination with other electronics facilities.

The already mentioned advantage of the very fast response speed of the one individual microrelay cells works when several microrelay cells are connected advantageously without scaling directly in the entire microrelay scarf ter a. This means that even with large specification values, Realize quickly responding residual current circuit breakers. Ver comparable conventional residual current circuit breakers are due to the inertia of the moving masses, on the other hand, are considerably restricted.

A further embodiment of the invention consists of a double function of Evaluation device that the residual current protection switch according to the invention direction to a second function as an overcurrent protection switching device. The invention is an equivalent to a conventional electromagnetic contactor. For this purpose, the evaluation device compares the signals of the currents sensors with a threshold value defining an overcurrent and opens the or the affected micro relay switch in response to the result of this Comparative. Again, the disclosure content of the previously cited message "New electrical switching device" referenced.

The invention can be implemented in various integration variants. To the one or the micro-relay switch, the evaluation device and opp possibly also the Hall sensors are each designed as semiconductor chips that are mounted together on a circuit board. Here the invention already shows we considerable advantages because of the design of the semiconductor technology Micro relay switch for the components involved using the same assembly technology or at least very similar assembly technologies with small size and ge light weight can be used. In this context, Special to point out that Hall sensors also on a chip, for example  executed on a silicon chip, or another substrate material could be. As an example of a design very related to microelectronics reference is made to "Cylindrical Hall Device" by H. Blanchard, L. Chiesi, R. Racz and R. S. Popovic, Proceedings IEDM 96, pages 541-544, IEEE 1996.

However, the invention is also very well suited to different components to combine a chip with each other. For example, the evaluations can be direction and the micro-relay switch can be integrated. With a suitable Hall sensor technology can also be integrated. Other On the one hand, it may be useful to only close the evaluation device and the Hall sensors integrate while the micro relay switch as a separate chip or separate Chips are running. This allows the combination of a standard component for the evaluation device and the Hall sensors with different levels for different electrical designs of the micro relay switch with regard to their current and voltage load. The integration of additional electronics shear components, e.g. B. of temperature sensors for a temperature-controlled Reading of the micro relay switch, timer circuits etc. is possible.

Devices for displaying the response can also be integrated the residual current protection switching device to a residual current (or also to an overcurrent or an elevated temperature) in optical or acoustic Wise.

In the following, a specific embodiment of the Invention described. Features disclosed can also be used individually or in combinations other than those shown are essential to the invention.

Fig. 1 is a schematic circuit diagram showing a micro-relay switch of an inventive fault current protective switch means, and

FIG. 2 shows the complete residual current protection switching device with two micro relay switches according to FIG. 1.

Fig. 1 shows a consisting of 17 series-connected stages 2 , each with 45 parallel ge microrelay cells 3 existing microrelay switches 1 . Technically, each microrelay cell 3 corresponds to the Siemens silicon microrelay already mentioned and is electrically connected to a microrelay cell 3 of the preceding and one of the subsequent stages 2 . In the last and in the first of the stages 2 , the connections to the outer side are brought together and connected to a common connection of the microrelay switch 1 .

One can also see in a highly schematic representation a movable contact piece 4 , which here corresponds to an electrostatically bendable or deflectable spring tongue. It is essential in the switching device according to the invention that all these movable contact pieces 4 work synchronously, ie are opened and closed by a single common signal, insofar as parts of a jointly constructed uniform switch act.

Each individual microrelay cell 3 can interrupt a voltage of approximately 24 V, so that a turn-off voltage of 400 V results for the microrelay switch 1 . This is a value that is favorable for many applications; values above 200 or 300 V are particularly preferred.

The switchable load current for each microrelay cell 3 is approximately 200 mA and thus gives a total current of 9 A for the microrelay switch 1 .

This microrelay switch 1 requires a total activation power of only 5 mW and shows in the conductive state a power loss in the order of 0.6-6 W. The latter value can, however, be improved by further improving the contacts and possibly increasing the closing force of the microrex cells lower further. Particularly in view of the extraordinarily low activation performance, there is evidently scope for the closing force.

The arrangement of individual microrelay cells 3 shown in FIG. 1 overall forms a microrelay switch 1 in the sense of the invention. It is essential that the microrelay switch 1 is opened and closed uniformly, ie all movable contact pieces 4 of the individual microrelay cells 3 are opened or closed simultaneously. Therefore, the control panel from the micro relay cells 3 behaves like a single switch 1 .

Fig. 2 shows two of the microrelay switch 1 shown in Fig. 1 in an inventive residual current protection switching device. The first micro relay switch is designated by the reference number 1 and the second micro-relay switch, which is constructed identically, by the reference number 1 '. The first micro switch 1 and the second micro switch 1 'are each in a first current path 8 and a second current path 8' is connected, the two current paths 8, 8 'of two in the upper part of FIG. 2 discernible lines are branched off and in the lower region of Fig. 2 terführen to a consumer knows. For example, the first current path 8 corresponds to a phase line and the second current path 8 'corresponds to the associated neutral conductor. An earth line is not shown because it plays no role in the invention.

The two microrelay switches 1 , 1 ', more precisely their respective contact pieces 4 , are controlled via a control line 9 . This control line 9 is identical for both microrelay switches 1 , 1 'because the microrelay switches 1 , 1 ' are switched together and at the same time. Merely because of the galvanic isolation between the phase-conducting first current path 8 and the second neutral conductor path 8 ', two separate microrelay switches 1 , 1 ' are provided. A common microrelay switch could also be used if it has galvanically isolated connections for the current paths, which show sufficient dielectric strength in relation to one another.

The common control line 9 leads to an evaluation device 7 , which has two parts 7 a and 7 b with regard to their function. Both parts 7 a and 7 b of the evaluation device 7 are supplied with a respective output signal of a first Hall sensor 5 and a second Hall sensor 5 '. The first Hall sensor 5 detects the current through the first current path 8 and the Hall sensor 5 'detects the current through the second current path 8 '. (Each of the Hall sensors 5 , 5 'requires a drive power of approximately 60 to 360 mW). The part 7 a of the evaluation device 7 determines from the signals of the Hall sensors 5 , 5 'the sum of the currents through the current paths 8 , 8 ' taking into account their direction, that is to say the difference in the amounts. If this sum or difference to a concentration relative small-sized threshold of about 5 mA, 7 a the evaluation device 7 is the part of a drive signal via the drive 9 from which the two micro-relay switches 1, 1 'within about 150 microseconds after the Detection of the fault current, ie the excessive current sum or difference opens. This means that both current paths 8 , 8 'are interrupted, and the defect to be assumed due to the fault current in the consumer supplied by the current paths 8 , 8 ' can be remedied.

On the other hand, the part 7 b of the evaluation device 7 monitors the signals of the Hall sensors 5 , 5 'for themselves, ie compares the detected current quantities individually with a threshold value, which represents the maximum permissible current in the current paths. If an upper stream, so the threshold value is ten überschrit, the part 7 makes b the evaluation device 7 in the same manner for a so diate opening the microrelay switch 1 and 1 '.

The residual current protection switching device according to the invention thus simultaneously has the function of an overcurrent protection switching device. It is clear that here the same micro relay switch 1 , 1 ', Hall sensors 5 , 5 ' and the same control line 9 can be used. In addition, the representation of the evaluation device 7 as consisting of two parts 7 a and 7 b is based only on the function of the evaluation device 7 . The same circuit units can be used to a large extent within the evaluation device 7 for the two functions 7 a and 7 b, for example the same input stages for the signals from the Hall sensors 5 , 5 ', the same control stage for the micro relay switch 1 , 1 'etc. The difference between the two parts only exists in the signal processing itself, ie between the comparison between two current signals with a tolerance specified by the fault current threshold on the one hand and the comparison of the respective individual current signal with the overcurrent threshold value on the other.

The evaluation device 7 is designed as an integrated Si analog circuit. The Hall sensors 5 , 5 'are designed on a Si substrate in accordance with the previously cited publication "Cy lindrical Hall Device". In the variant shown here in FIG. 2, the evaluation device 7 , the Hall sensors 5 , 5 'and the two microrelay switches 1 , 1 ' are also integrated on the same Si chip 6 . In this embodiment, the residual current protection switching device according to the invention corresponds to a single Si chip 6 , which is provided with a suitable housing with corresponding connections for a conventional household power line, which correspond to the two current paths 8 , 8 'outside the housing. The housing is only symboically shown in Fig. 2 with the frame 10 and can for example correspond to a conventional connector housing.

Claims (16)

1. Electrical residual current protection switching device with a first micro relay switch ( 1 ) in a first current path ( 8 ) and a Auswerteinrich device ( 7 ) for receiving and evaluating signals of a current through the first current path ( 8 ) detecting the first current sensor ( 5 ) and a second current sensor ( 5 ') which detects a current through a second current path ( 8 ') by comparing them with one another and opening the first microrelay switch ( 1 ) in response to a result of the evaluation. 2. Electrical residual current protection switching device according to claim 1, wherein the evaluation device ( 7 ) for receiving and evaluating signals of the first and the second current sensor ( 5 , 5 ') as well as a third current sensor detecting a current through a third current path and a current is designed by a fourth current path detecting fourth Stromsen sors. 3. Electrical residual current protection switching device according to claim 1 or 2, wherein the current sensors ( 5 , 5 ') are part of the switching device and formed by Hall sensors. 4. Electrical residual current protection switching device with a first microrelay switch ( 1 ) in a first current path ( 8 ) and a total current through the first current path and at least one second current path detecting first neighboring current sensor and an evaluation device for receiving and evaluating a signal of the he first total current sensor and opening the first micro-relay switch ( 1 ) in response to a result of the comparison. 5. Electrical residual current protection switching device according to claim 4 with egg nem a second and a third current sensor or with a second Ge Velocity current sensor for detecting the currents or the total current  by a third and a fourth current path, the evaluations being is designed for receiving and evaluating signals from the first total current sensor and the second and third current sensors or the second total current sensor. 6. Electrical residual current protection switching device according to one of the vorste existing claims with a second microrelay switch ( 1 ') in the two-th current path ( 8 '), in which the evaluation device ( 7 ) and the second microrelay switch ( 1 ') in response to the result of Evaluation opens. 7. Electrical residual current protection switching device according to claim 6 in Ver binding with one of claims 2, 3, 5 with at least a third Mi krorelaisschalter in at least the third current path, in which the Auswer teeinrichtung also appealing to at least the third microrelay switch opens on the result of the evaluation. 8. Electrical residual current protection switching device according to claim 4 or 5, also in connection with claim 6 or 7, in which the current sensor or sensors ( 5 , 5 ') or total current sensors are formed by Hall sensors. 9. Electrical residual current protection switching device according to one of the preceding claims, in which the one or more microrelay switches ( 1 , 1 ') have a voltage-dividing series circuit of microrelay cells ( 3 ). 10. Electrical residual current protection switching device according to one of the preceding claims, in which the one or more microrelay switches ( 1 , 1 ') have a current-dividing parallel connection of microrelay cells ( 3 ). 11. Electrical residual current protection switching device according to one of the vorste existing claims, wherein the one or more microrelay switches ( 1 , 1 ') each have at least one microrelay ( 3 ) with an electrostatically mechanically moved contact piece ( 4 ). 12. Electrical residual current protection switching device according to one of the preceding claims, in which the evaluation device ( 7 ) compares the signals of the current sensor (s) ( 5 , 5 ') or the total current sensors also with an overcurrent threshold value and the micro relay switch (s) ( 1 , 1 ') opens in response to the result of this comparison. 13. Electrical residual current protection switching device according to one of the first existing claims, in which the or the micro relay switch, the evaluations device and possibly the Hall sensors as chips on egg ner board are integrated. 14. Electrical residual current protection switching device according to one of the preceding claims, in which the one or more microrelay switches ( 1 , 1 ') and the evaluation device ( 7 ) are integrated on a chip ( 6 ). 15. Electrical residual current protection switching device according to claim 3 or 8, also in connection with one of claims 9-13, in which the evaluation device ( 7 ) and the Hall sensors ( 5 , 5 ') are integrated on a chip ( 6 ) . 16. Electrical residual current protection switching device according to claim 3 or 8, also in connection with one of claims 9-13, in which the or the Mi krorelaisschalter ( 1 , 1 '), the evaluation device ( 7 ) and the Hall sensors ( 5 , 5 ') are integrated on a chip ( 6 ).