SWITCHING CONTACT AND A SECOND NON-LATCHED SWITCHING CONTACT

TECHNICAL FIELD

The invention relates to an arrangement with a circuit breaker and a contactor or relay. The circuit breaker comprises a first switching contact, a trigger unit, which is designed to open the first switching contact in case that a current flowing over the first switching contact exceeds a first current threshold, and a latch, which is designed to keep the first switching contact open until on-site manual intervention. The contactor or relay comprises a second switching contact, which is connected in series with the first switching contact of the circuit breaker, and an actuating unit acting on the second switching contact.

Moreover, the invention relates to an over current protection device with a first switching contact, a trigger unit, which is designed to open the first switching contact in case that a load current flowing over the first switching contact exceeds a first load current threshold, and a latch, which is designed to keep the first switching contact open until on-site manual intervention.

Finally, the invention relates to a residual current circuit breaker with overcurrent protection, which comprises an over current protection device of the above kind and an additional trigger unit, which is designed to open the first switching contact also in case that a residual current flowing over the first switching contact exceeds a first residual current threshold.

BACKGROUND ART

An arrangement, an over current protection device and a residual current circuit breaker with overcurrent protection of the above kind are generally known in prior art. The devices trigger the first switching contact in case of an excessive load current (e.g. > 15 A) and/or in case of a residual current (e.g. > 30 mA). In the first case, an exceptional high load causes triggering of the first switching contact. In the second case, insulation faults are the reason for the triggered first switching contact. The first switching contact is latched what means that the first switching contact is kept open until on-site manual intervention, for example until somebody operates a handle of the switching device which is coupled with the latch and the first switching contact.

Basically, this is standard in most electrical appliances and guarantees for a high safety level. However, the necessity of an on-site manual intervention for switching the switching device on again is also a drawback in some cases. For example, a socket or an access point to the electric grid in the public space may be used for a variety of devices, of which at least some can cause excessive load currents and/or can have insultation faults. One example for this situation is a battery charging station for electric cars. Electric cars can cause quite high load currents and they can also have insulation faults. Even in case that the load current and/or the residual current stays below the first current threshold it could be useful to keep them away from the socket to avoid that minor changes or fluctuations of the load current and/or the residual current cause triggering of the first switching contact and in turn require onsite manual intervention. A comparably long down time of the grid access point is the consequence then because responsible personnel must move to the site to operate the handle on the switching device. In this example, that means that no cars can be charged during a comparably long time what is a major drawback given the number of electric cars in relation to the number of charging stations.

DISCLOSURE OF INVENTION

Accordingly, an object of the invention is the provision of an improved arrangement, an improved over current protection device and an improved residual current circuit breaker with overcurrent protection. In particular, a solution shall be provided, which overcomes the drawbacks mentioned hereinbefore and provides substantially uninterrupted power at public grid access points.

The object of the invention is solved by an arrangement as disclosed in the opening paragraph which additionally comprises a current sensor, which is designed to sense the current flowing over the first switching contact (which equals the current flowing over the second switching contact because of the series connection of the first and the second switching contact), an electronic threshold switch with an input and an output, wherein the input is connected to the current sensor and wherein the output is functionally coupled to the actuating unit of the contactor or relay, and an external on terminal, which is functionally coupled to the actuating unit of the contactor or relay.

The electronic threshold switch is designed to provide at its output a current exceedance signal in case that the current sensed by the current sensor exceeds a second current threshold, which is below the first current threshold, and a normal current signal in case that the current sensed by the current sensor drops below the second current threshold or drops below a third current threshold, which is below the second current threshold.

A transition from the normal current signal to the current exceedance signal causes the actuating unit opening the second switching contact and a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

Moreover, the object of the invention is solved by an over current protection device (e.g. embodied as a “miniature circuit breaker” or “MCB” for short or as a “molded case circuit breaker” or “MCCB” for short) as disclosed in the opening paragraph which additionally comprises a current sensor, which is designed to sense the load current flowing over the first switching contact (which equals the current flowing over the second switching contact because of the series connection of the first and the second switching contact), an electronic threshold switch with an input and an output, wherein the input is connected to the current sensor and wherein the output is connected to a terminal of the over current protection device.

The electronic threshold switch is designed to provide at its output a current exceedance signal in case that the load current sensed by the current sensor exceeds a second load current threshold, which is below the first load current threshold, and a normal current signal in case that the load current sensed by the current sensor drops below the second load current threshold or drops below a third load current threshold, which is below the second load current threshold. Finally, the object of the invention is solved by a residual current circuit breaker with overcurrent protection (“RCBO” for short) as disclosed in the opening paragraph which comprises an over current protection device as described above and an additional trigger unit, which is designed to open the first switching contact also in case that a residual current flowing over the first switching contact exceeds a first residual current threshold.

By the proposed measures, the grid is switched off by means of the contactor or relay well before the load current and/or residual current reach dangerous levels. On the one hand, this means that the power is switched off even in cases which are actually not yet dangerous, for example if an electric car needs comparably much charging power or causes some residual current. On the other hand, situations are avoided where minor changes or fluctuations of the load current and/or the residual current cause triggering of the first switching contact and in turn require on-site manual intervention. Instead, just the contactor or relay is switched off, which can be switched on again remotely or automatically after a short safety time period. Accordingly, long down time of the grid access point is avoided because no personnel must move to the site to operate the handle on the switching device.

The arrangement can be built up in different ways. In one embodiment, the circuit breaker has a circuit breaker housing and the contactor or relay has a separate contactor or relay housing. So, devices may be combined in a very flexible way. In an alternative embodiment, the circuit breaker and the contactor or relay have a common housing. In this case, the arrangement is very compact.

One should note that the term “load current” may refer to “AC load current”, “DC load current” or to both “AC and DC load current”. The same counts fort the term “residual current”, which may refer to “AC residual current”, “DC residual current” or to both “AC and DC residual current”. It should also be noted at this point that the term “residual current” may be replaced by “fault current” throughout the application, wherein the above definition equally applies. Hence, the term “fault current” may refer to “AC fault current”, “DC fault current” or to both “AC and DC fault current”.

In this context, one should also note that current sensor may be embodied in different ways, i.e. as an AC load current sensor, a DC load current sensor, a combined AC/DC load current sensor, an AC residual current sensor, a DC residual current sensor, a combined AC/DC residual current sensor or as any combination of this sensors. In particular, the term “current sensor” may also denote a group of sub sensors of the above kind.

Wherever reference is made to “current thresholds” one should note that a current threshold is linked to a load current or to a residual current. A residual current threshold usually is 30 mA or less, whereas a load current threshold is much higher and may even reach several kA for example.

Further advantageous embodiments are disclosed in the claims and in the description as well as in the figures.

In one embodiment, the contactor or relay is a bi-stable one and the output of the electronic threshold switch and the external on terminal are fed to the actuating unit of the bi-stable contactor or relay (case a). In this case, actuating pulses are directly feed to the actuating unit which then holds the second switching contact in the given position. Bi-stable contactors or relays may have one coil or two coils for actuating the second switching contact.

In an alternative embodiment, the contactor or relay is a monostable one and the arrangement comprises a RS-flip-flop, wherein the external on terminal is fed to a set input of the RS-flip-flop and the output of the electronic threshold switch is fed to a reset input of the RS-flip-flop or vice versa and wherein an output of the RS-flip-flop is fed to the actuating unit of the monostable contactor or relay (case b). Monostable contactors or relays usually have one coil for actuating the second switching contact and have one switching position, in which the coil is energized, and another one, in which it is non-energized. To hold the second switching contact in a desired position, the use of an RS-flip-flop is proposed. If the second switching contact is closed in the energized state, the electronic threshold switch is fed to the reset input of the RS-flip- flop and the external on terminal is fed to the set input of the RS-flip-flop. So, an overcurrent event toggles the second switching contact to its open position, whereas an external switch-on pulse toggles the second switching contact to its closed position. If the second switching contact is open in the energized state, the electronic threshold switch is fed to the set input of the RS-flip-flop and the external on terminal is fed to the reset input of the RS-fl ip-flop. So, again an overcurrent event toggles the second switching contact to its open position, whereas an external switch-on pulse toggles the second switching contact to its closed position. Generally, the RS-flip-flop may be part of the circuit breaker or may be part of the contactor or relay.

Advantageously, the arrangement comprises an external off terminal and a logical OR-function, wherein the output of the electronic threshold switch and the external off terminal are fed to inputs of the logical OR-function and an output of the logical OR- function is fed to the actuating unit of the bi-stable contactor or relay in case a) or to the reset input of the RS-flip-flop (if the second switching contact is closed in the energized state) or to the set input of the RS-flip-flop respectively (if the second switching contact is open in the energized state) in case b). In this way, the contactor or relay may also be switched off by an external switch-off pulse. For this reason, the arrangement in particular may comprise an additional external off terminal, which is connected to the input of the OR-function. Generally, the OR-function may be part of the circuit breaker or may be part of the contactor or relay. For example, the OR- function may be embodied as OR-gate.

In one embodiment of the arrangement, the circuit breaker can be designed as a residual current device (“ROD” for short - alternatively “residual current circuit breaker” or “RCCB” for short or “ground fault circuit interrupter” or “GFCI” for short), wherein the current flowing over the first switching contact is a residual current, the first current threshold is a first residual current threshold, the second current threshold is a second residual current threshold, the current exceedance signal is a residual current exceedance signal, the normal current signal is a normal residual current signal, the trigger unit is designed to open the first switching contact in case that the residual current flowing over the first switching contact exceeds the first residual current threshold, the current sensor is designed as a residual current sensor for sensing the residual current flowing over the first switching contact, the electronic threshold switch is designed to provide at its output the residual current exceedance signal in case that the residual current sensed by the current sensor exceeds the second residual current threshold, wherein the electronic threshold switch is designed to provide the normal residual current signal in case that the residual current sensed by the current sensor drops below the second residual current threshold or drops below a third residual current threshold, which is below the second residual current threshold, wherein a transition from the normal residual current signal to the residual current exceedance signal causes the actuating unit opening the second switching contact and wherein a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

In this embodiment, the arrangement comprises a residual current device. Accordingly, the arrangement triggers the first switching contact in case of residual currents or fault currents.

In a very advantageous embodiment of the aforementioned arrangement, the first current threshold is a first DC residual current threshold, the second current threshold is a second DC residual current threshold, the current exceedance signal is a DC residual current exceedance signal, the normal current signal is a normal DC residual current signal, the trigger unit is designed to open the first switching contact in case that a DC residual current flowing over the first switching contact exceeds the first DC residual current threshold, the circuit breaker comprises an additional trigger unit, which is designed to open the first switching contact in case that an AC residual current flowing over the first switching contact exceeds a first AC residual current threshold, the current sensor is designed as a DC residual current sensor designed for sensing a DC residual current flowing over the first switching contact, the electronic threshold switch is designed to provide at its output the DC residual current exceedance signal in case that the DC residual current sensed by the current sensor exceeds the second DC residual current threshold, wherein the electronic threshold switch is designed to provide the normal DC residual current signal in case that the DC residual current sensed by the current sensor drops below the second DC residual current threshold or drops below a third DC residual current threshold, which is below the second DC residual current threshold, wherein a transition from the normal DC residual current signal to the DC residual current exceedance signal causes the actuating unit opening the second switching contact and wherein a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

In this embodiment, the additional trigger unit for the first switching contact is sensitive to an AC residual current, whereas the current sensor senses the DC residual current. Thus the electronic threshold switch and the second switching contact are sensitive to an DC residual current. This embodiment is particularly useful for charging stations for electric vehicles because electric vehicles primarily cause DC fault currents. As the cars move away again, also the reason for the DC fault current disappears. Hence, it is beneficial to clear such situations remotely. However, in an alternative embodiment, the AC residual current and the DC residual current may change their roles in the above definition.

Advantageously, the aforementioned residual current device of the arrangement can comprise an additional over current protection switch in series with the first switching contact and is then designed as a residual current circuit breaker with overcurrent protection (“RCBO” for short). Accordingly, the arrangement triggers the first switching contact both in case of residual currents and in case of excessive load currents. However, one should note that the electronic threshold switch does not sense load currents in this embodiment but is only sensitive to residual currents. Accordingly, the second switching contact is triggered only in case of residual currents.

In another embodiment of the arrangement, the circuit breaker can be designed as an over current protection device (e.g. as a “miniature circuit breaker” or “MCB” for short or as a “molded case circuit breaker” or “MCCB” for short), wherein the current flowing over the first switching contact is a load current, the first current threshold is a first load current threshold, the second current threshold is a second load current threshold, the current exceedance signal is a load current exceedance signal, the normal current signal is a normal load current signal, the trigger unit is designed to open the first switching contact in case that the load current flowing over the first switching contact exceeds the first load current threshold, the current sensor is designed as a load current sensor designed for sensing the load current flowing over the first switching contact, the electronic threshold switch is designed to provide at its output the load current exceedance signal in case that the load current sensed by the current sensor exceeds the second load current threshold, wherein the electronic threshold switch is designed to provide the normal load current signal in case that the load current sensed by the current sensor drops below the second load current threshold or drops below a third load current threshold, which is below the second load current threshold, wherein a transition from the normal load current signal to the load current exceedance signal causes the actuating unit opening the second switching contact and wherein a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

In this embodiment, the arrangement comprises an over current protection device. Accordingly, the arrangement triggers in case of excessive load currents.

In a very advantageous embodiment of the aforementioned arrangement, the first current threshold is a first DC load current threshold, the second current threshold is a second DC load current threshold, the current exceedance signal is a DC load current exceedance signal, the normal load current signal is a normal DC load current signal, the trigger unit is designed to open the first switching contact in case that a DC load current flowing over the first switching contact exceeds the first DC load current threshold, the circuit breaker comprises an additional trigger unit, which is designed to open the first switching contact in case that an AC load current flowing over the first switching contact exceeds a first AC load current threshold, the current sensor is designed as a DC load current sensor designed for sensing a DC load current flowing over the first switching contact, the electronic threshold switch is designed to provide at its output the DC load current exceedance signal in case that the load current sensed by the current sensor exceeds the second DC load current threshold, wherein the electronic threshold switch is designed to provide the normal DC load current signal in case that the DC load current sensed by the current sensor drops below the second DC load current threshold or drops below a third DC load current threshold, which is below the second DC load current threshold, wherein a transition from the normal DC load current signal to the DC load current exceedance signal causes the actuating unit opening the second switching contact and wherein a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

In this embodiment, the additional trigger unit for the first switching contact is sensitive to an AC load current, whereas the current sensor senses the DC load current. Thus the electronic threshold switch and the second switching contact are sensitive to an DC load current. This embodiment is particularly useful for charging stations for electric vehicles because electric vehicles, if at all, primarily can cause excessive DC load currents. As the cars move away again, also the reason for the DC overload disappears. Hence, it is beneficial to clear such situations remotely. However, in an alternative embodiment, the AC load current and the DC load current may change their roles in the above definition.

Advantageously, the aforementioned over current protection device of the arrangement can comprise an additional residual current switch in series with the first switching contact and is then designed as a residual current circuit breaker with overcurrent protection (RCBO). Accordingly, the arrangement triggers the first switching contact both in case of residual currents and in case of excessive load currents, too. However, one should note that the electronic threshold switch does not sense residual currents in this embodiment but is only sensitive to load currents.

Accordingly, the second switching contact is triggered only in case of high load currents.

In one further embodiment of the proposed arrangement, the circuit breaker can be designed as a residual current circuit breaker with overcurrent protection (RCBO) and in addition to the features of the aforementioned over current protection device can comprise an additional trigger unit, which is designed to open the first switching contact also in case that a residual current flowing over the first switching contact exceeds a first residual current threshold, and an additional current sensor, which is designed as a residual current sensor designed for sensing the residual current flowing over the first switching contact and which is connected to an input of the electronic threshold switch.

The electronic threshold switch additionally is designed to provide at its output a residual current exceedance signal in case that the residual current sensed by the additional current sensor exceeds a second residual current threshold, and a normal residual current signal in case that the residual current sensed by the additional current sensor drops below the second residual current threshold or drops below a third residual current threshold, which is below the second residual current threshold.

Opening the second switching contact by the actuating unit is caused if either a transition from the normal load current signal to the load current exceedance signal or a transition from the normal residual current signal to the residual current exceedance signal is output by the electronic threshold switch and a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

This is another embodiment of an arrangement triggering the first switching contact both in case of residual currents and in case of excessive load currents. In contrast to other versions disclosed hereinbefore, the electronic threshold switch senses both the residual current and the load current in this embodiment. Accordingly, the second switching contact is triggered both in case of residual currents and in case of high load currents. It should also be noted that the electronic threshold switch outputs dedicated current exceedance signals and normal current signals for both the residual current and the load current.

In another embodiment of the proposed arrangement, the circuit breaker can be designed as a residual current circuit breaker with overcurrent protection (RCBO) and in addition to the features of the aforementioned over current protection device can comprise an additional trigger unit, which is designed to open the first switching contact also in case that a residual current flowing over the first switching contact exceeds a first residual current threshold, and an additional current sensor, which is designed as a residual current sensor designed for sensing the residual current flowing over the first switching contact and which is connected to an input of the electronic threshold switch.

The electronic threshold switch additionally is designed to provide at its output a current exceedance signal in case that the load current sensed by the current sensor exceeds the second load current threshold or in case that the residual current sensed by the additional current sensor exceeds a second residual current threshold, and a normal current signal in case that the load current sensed by the current sensor drops below the second load current threshold or drops below a third load current threshold, which is below the second load current threshold, and the residual current sensed by the additional current sensor drops below the second residual current threshold or drops below a third residual current threshold, which is below the second residual current threshold.

A transition from the normal current signal to the current exceedance signal causes the actuating unit opening the second switching contact and a switch-on pulse fed to the external on terminal causes the actuating unit closing the second switching contact.

This is yet another embodiment of an arrangement triggering the first switching contact both in case of residual currents and in case of excessive load currents. Again, the electronic threshold switch senses both the residual current and the load current in this embodiment. Accordingly, the second switching contact is triggered both in case of residual currents and in case of high load currents. However, in this embodiment, the electronic threshold switch outputs a common current exceedance signal and a common normal current signal for the residual current and the load current.

In one embodiment, the residual current circuit breaker with overcurrent protection (RCBO) in addition to the features of the aforementioned over current protection device can comprise an additional trigger unit, which is designed to open the first switching contact also in case that a residual current flowing over the first switching contact exceeds a first residual current threshold, and an additional current sensor, which is designed as a residual current sensor designed for sensing the residual current flowing over the first switching contact and which is connected to an input of the electronic threshold switch.

The electronic threshold switch additionally is designed to provide at its output a residual current exceedance signal in case that the residual current sensed by the additional current sensor exceeds a second residual current threshold, and a normal residual current signal in case that the residual current sensed by the additional current sensor drops below the second residual current threshold or drops below a third residual current threshold, which is below the second residual current threshold.

This is an embodiment of a residual current circuit breaker with overcurrent protection, which triggers the first switching contact both in case of residual currents and in case of excessive load currents. The electronic threshold switch senses both the residual current and the load current in this embodiment and outputs dedicated current exceedance signals and normal current signals for both the residual current and the load current, for example to an external terminal.

In another alternative embodiment, the residual current circuit breaker with overcurrent protection (RCBO) in addition to the features of the aforementioned over current protection device can comprise an additional trigger unit, which is designed to open the first switching contact also in case that a residual current flowing over the first switching contact exceeds a first residual current threshold, an additional current sensor, which is designed as a residual current sensor designed for sensing the residual current flowing over the first switching contact and which is connected to an input of the electronic threshold switch.

The electronic threshold switch additionally is designed to provide at its output a current exceedance signal in case that the load current sensed by the current sensor exceeds the second load current threshold or in case that the residual current sensed by the additional current sensor exceeds a second residual current threshold, and a normal current signal in case that the load current sensed by the current sensor drops below the second load current threshold or drops below a third load current threshold, which is below the second load current threshold, and the residual current sensed by the additional current sensor drops below the second residual current threshold or drops below a third residual current threshold, which is below the second residual current threshold.

This is an embodiment of a residual current circuit breaker with overcurrent protection, which triggers the first switching contact both in case of residual currents and in case of excessive load currents. The electronic threshold switch senses both the residual current and the load current in this embodiment but in contrast to the aforementioned embodiment outputs a common current exceedance signal for the residual current and the load current, for example to an external terminal.

BRIEF DESCRIPTION OF DRAWINGS

The invention now is described in more detail hereinafter with reference to particular embodiments, which the invention however is not limited to.

Fig. 1 shows a schematic view of an inventive arrangement acting as a residual current device;

Fig. 2 shows an exemplary timing diagram of the current over the switching contacts, the output of the electronic threshold switch and the state of the switching contacts;

Fig. 3 shows a schematic view of an inventive arrangement acting as an over current protection device;

Fig. 4 shows a schematic view of an inventive arrangement acting as a residual current circuit breaker with overcurrent protection;

Fig. 5 like Fig. 4 but with the electronic threshold switch being connected to the load current sensor;

Fig. 6 like Fig. 4 but with the electronic threshold switch being connected to both the load current sensor and the residual current sensor;

Fig. 7 shows a schematic view of an inventive arrangement with an additional external switch off terminal; Fig. 8 shows a schematic view of an inventive arrangement with a RS-fl ip-flop coupled to the second switching contact;

Fig. 9 like Fig. 8 but with a common housing for the circuit breaker and the contactor or relay;

Fig. 10 shows a schematic view of an inventive arrangement with a DC residual current sensor and an AC residual current sensor and

Fig. 11 shows a schematic view of an inventive arrangement with a DC load current sensor and an AC load current sensor.

DETAILED DESCRIPTION

Generally, same parts or similar parts are denoted with the same/similar names and reference signs. The features disclosed in the description apply to parts with the same/similar names respectively reference signs. Indicating the orientation and relative position is related to the associated figure, and indication of the orientation and/or relative position has to be amended in different figures accordingly as the case may be.

Fig. 1 shows a schematic view of an arrangement 1a, which comprises a circuit breaker 2a and a contactor or relay 3a.

The circuit breaker 2a comprises a circuit breaker housing 4, a first switching contact S1 , a trigger unit 5, a latch 6, a handle 7, a current sensor 8a, an electronic threshold switch 9 and five terminals T1..T5. In the example of Fig. 1 , a neutral line N is connected to the terminals T1 , T2, and one phase or more phases L1..L3 are connected to the terminals T3, T4. In Fig. 1 , symbolically only one conductor is depicted for the phases L1 ,.L3 but in reality, there is a separate conductor for each phase L1 ,.L3. Similar considerations can be made for the first switching contact S1 . In Fig. 1 , symbolically just one first switching contact S1 is depicted for the phases L1 ,.L3 but in reality, there can be a separate first switching contact S1 for each phase L1 ,.L3.

A current ILI ..L3 flows from the phases L1 ,.L3 into the terminal T3, and a current IN flows back to the neutral line N through the terminal T1 . The current sensor 8a is embodied as residual current sensor in this embodiment and senses the residual or fault current, which is the sum of the currents ILI ..L3 and the current IN. Both the trigger unit 5 and the electronic threshold switch 9 are connected to the current sensor 8a.

The trigger unit 5 is designed to open the first switching contact S1 , in case that a current flowing over the circuit breaker 2a exceeds a first current threshold TH1 . In this concrete embodiment, said current is a residual current and said first current threshold TH1 is a first residual current threshold TH1 .

The latch 6 keeps the first switching contact S1 open until on-site manual intervention, i.e. until someone closes the first switching contact S1 by operating the handle 7. Commonly, a circuit breaker 2a also comprises a test circuit and a test push button which are however not shown in Fig. 1 for the sake of brevity.

The electronic threshold switch 9 has an input and an output, wherein the input is connected to the current sensor 8a and wherein the output is connected to the terminal T5. The electronic threshold switch 9 is designed to provide at its output a current exceedance signal in case that the current sensed by the current sensor 8a exceeds a second current threshold TH2, wherein the second current threshold TH2 is below the first current threshold TH1 . Further on, the electronic threshold switch 9 is designed to provide a normal current signal in case that the current sensed by the current sensor 8a drops below the second current threshold TH2 or drops below a third current threshold TH3, which is below the second current threshold TH2. The latter provides a hysteresis if this is needed.

The contactor or relay 3a in this embodiment comprises a contactor or relay housing 10, a second switching contact S2, an actuating unit 11 acting on the second switching contact S2 and six terminals T6..T11. In the example of Fig. 1 , the neutral line N is connected to the terminals T6, T7, and the phase or more phases L1..L3 are connected to the terminals T8, T9. The second switching contact S2 is connected in series with the first switching contact S1 of the circuit breaker 2a. Like this is the case for the first switching contact S1 , in Fig. 1 , symbolically just one second switching contact S2 is depicted for the phases L1 ,.L3 but in reality, there can be a separate second switching contact S2 for each phase L1 ,.L3. The output of the electronic threshold switch 9 is functionally coupled to the actuating unit 11 of the contactor or relay 3a. Concretely, the terminal T10 is connected to the actuating unit 11 , and the output of the electronic threshold switch 9 is connected to the actuating unit 11 via a connection between the terminals T5 and T10. Further on, the terminal T11 forms an external on terminal, which is functionally coupled to the actuating unit 11 of the contactor or relay 7, too. Concretely, the terminal T11 is connected to the actuating unit 11.

The actuating unit 11 is designed in a way that a transition from the normal current signal to the current exceedance signal causes the actuating unit 11 opening the second switching contact S2 and a switch-on pulse fed to the external on terminal T11 causes the actuating unit 11 closing the second switching contact S2. For example, the contactor or relay 7 can be a bi-stable one for that reason.

The function of the arrangement 1a is now explained by additional use of Fig. 2, which shows a current time diagram of the current I, which is the residual current in this example, at the very bottom, above a diagram of the current signal CS, a diagram of the switching state Ss2 of the second switching contact S2 and a diagram of the switching state Ssi of the first switching contact S1 at the very top.

In normal operation, both the first switching contact S1 and the second switching contact S2 are closed and conductively connect a load (not shown in Fig. 1 ) to the grid formed by the phases L1 ,.L3 and the neutral line N. As long as the residual current, which is monitored by the residual current sensor 8a and which is the sum of the currents ILI ..L3 and the current IN, is below the second current threshold TH2, both switching contacts S1 , S2 stay closed. The electronic threshold switch 9 outputs the normal current signal NCS in this state. If the residual current I exceeds the second current threshold TH2 because of an insulation fault on the load side which is the case at ti , the electronic threshold switch 9 changes its output from the normal current signal NCS to the current exceedance signal CES. This transition causes the actuating unit 11 opening the second switching contact S2 thus disconnecting the load from the grid. Because the second switching contact S2 cannot be opened in an infinitely short time, there is some delay until the currents ILI ..L3 are indeed cut off at t2. The electronic threshold switch 9 then changes back to the normal current signal NCS because the insulation fault is no longer effective because of the open second switching contact S2. One should note that at this first event of this functional description, the first switching contact S1 stays closed because the fault or residual current I, which causes opening the second switching contact S2, does not reach the first current threshold TH1 . So the trigger unit 5 does not get active.

The second switching contact S2 stays open until a switch-on pulse is fed to the external on terminal T11 which is the case at ts and which causes the actuating unit 11 closing the second switching contact S2. Because the first switching contact S1 is still closed, the load is then connected to the grid again. If the insulation fault is no longer present, the second switching contact S2 stays closed and the electronic threshold switch 9 outputs the normal current signal NCS. Accordingly, the load stays connected to the grid in this case.

If the insulation fault is still present and causes the residual current I to exceed the second current threshold TH2, the electronic threshold switch 9 immediately changes its output from the normal current signal NCS to the current exceedance signal CES thus causing the second switching contact S2 being opened again at. However, in Fig. 2, the residual current stays low for a while and the quickly rises starting from t4. At ts the residual current I exceeds the second current threshold TH2 and the electronic threshold switch 9 changes its output from the normal current signal NCS to the current exceedance signal CES again. This transition causes the actuating unit 11 opening the second switching contact S2 thus disconnecting the load from the grid. As can be seen in the diagram of the switching state Ss2, the second switching contact S2 cannot immediately change its state and so the residual current I also rises up to the first current threshold TH1 at te thus causing opening of the first switching contact S1 .

So, if the residual or fault current exceeds the first current threshold TH1 , generally not just the second switching contact S2 is opened but also the first switching contact S1 caused by the trigger unit 5. In this case, a switch-on pulse fed to the external on terminal T11 alone does not connect the load to the grid again, but additional on-site manual intervention is necessary because the latch 6 keeps the first switching contact open S1 until someone operates the handle 7 and in this way closes the first switching contact S1 again. In a nutshell, the arrangement 1a on the one hand provides normal functionality of a residual current breaker (RCD). Additionally, less critical insulation faults in fact also cause disconnecting the load from the grid but switch on does not require on-site manual intervention but can be initiated remotely by feeding a switch-on pulse to the external on terminal T11 . This can be done by wire but in principle also wirelessly if an appropriate wireless receiver is connected to the terminal T11 or even is part of the arrangement 1a and is connected to the actuating unit 11 .

Note that in Fig. 2 also a third current threshold TH3 is shown below the second current threshold TH2. To provide an optional hysteresis, the electronic threshold switch 9 can also be designed to provide a normal current signal NCS if the current I drops below the third current threshold TH3.

Fig. 3 now shows a schematic view of an arrangement 1 b, which is similar to the arrangement 1a of Fig. 1 . In contrast, the current sensor 8b of the circuit breaker 2b is embodied as load current sensor in this embodiment and senses the load current, which is the current ILI ..L3 (or alternatively the current IN). Accordingly, the circuit breaker 2b is designed as an over current protection device here (MCB or MCCB). The functional principle is pretty the same as for the arrangement 1a of Fig. 1 . However, the load current takes over the role of the residual current in the description of Figs. 1 and 2 then. Additionally, there may be an optional thermal overload sensor 12, which acts as a trigger unit for the first switching contact S1 , too. Commonly, such a thermal overload sensor 12 is used to detect a lower overload, which acts over a long time.

Fig. 4 now shows a schematic view of an arrangement 1c, which is similar to a combination of the arrangements 1a and 1 b of Figs. 1 and 3. Starting from the arrangement 1a of Fig. 1 , the arrangement 1c additionally has a thermal overload sensor 12 for the same reason as the arrangement 1b of Fig. 3. Moreover, the arrangement 1c additionally has load current sensor 8b like this is the case for the arrangement 1 b of Fig. 3, too. In addition, there is an additional trigger unit 13, which is connected to the load current sensor 8b. So, the first switching contact S1 is not only triggered if the residual current exceeds the first residual current threshold TH1 but also if the load current exceeds a load current threshold (or if the thermal overload sensor 12 gets too hot respectively). So, basically, the function of the arrangement 1 c of Fig. 4 equals the function of the arrangement 1 a of Fig. 1 plus the above load current and thermal protection. It should be noted at this point that the load current and thermal protection only act on the first switching contact S1 but not on the second switching contact S2 in this embodiment.

Fig. 5 shows a schematic view of an arrangement 1 d, which is similar to the arrangement 1 c of Fig. 4. In contrast, here the residual current sensor 8a is connected to the additional trigger unit 13 and the load current sensor 8b is connected to the trigger unit 5 and the electronic threshold switch 9. The function of the arrangement 1 d of Fig. 5 equals the function of the arrangement 1 c of Fig. 4, wherein however the roles of the residual current and the load current change. Nevertheless, the optional thermal overload sensor 12 still reacts on the load current and not on the residual current.

Fig. 6 shows a schematic view of an arrangement 1 e, which is similar to the arrangement 1 c of Fig. 3. In contrast, here both the residual current sensor 8a and the load current sensor 8b are connected to the trigger unit 5 and the electronic threshold switch 9. The function of the arrangement 1 e of Fig. 6 is similar the function of the arrangement 1 c of Fig. 4. However, both the residual current and the load current can trigger opening the first switching contact S1 and the second switching contact S2. Basically, there is logical OR between the residual current and the load current, meaning that either the residual current OR the load current can trigger opening the first switching contact S1 and the second switching contact S2. However, different first current thresholds TH1 and second current thresholds TH2 apply to the residual current and the load current (e.g. 30/20 mA for the residual current threshold and 100/90 A for the load current threshold). Also the functional description related to Fig. 2 similarly applies to the arrangement 1 e of Fig. 6. In this embodiment, the electronic threshold switch 9 outputs a common current exceedance signal and a common normal current signal for the residual current and the load current at the terminal T5. However, in an alternative embodiment, the electronic threshold switch 9 can also output dedicated current exceedance signals and normal current signals for both the residual current and the load current.

Fig. 7 shows a schematic view of an arrangement 1 f, which is similar to the arrangement 1 c of Fig. 4. In contrast, the contactor or relay 3f comprises an additional OR-function 14, which is embodied as OR-gate in this example, the output of which is connected to the actuating unit 11 and the inputs of which are connected to the terminals T10 and T12. So the second switching contact S2 cannot only be opened by the electronic threshold switch 9 but also by a pulse fed into terminal T12. Accordingly, the second switching contact S2 can also be switched off actively from remote. It should be noted that the contactor or relay 3f can also be used in combination with the circuit breakers 2a, 2b, 2d and 2e of Figs. 1 , 3, 5 and 6. Finally, it should also be noted that the OR-function 14 alternatively may be part of the circuit breaker 2f.

Fig. 8 shows a schematic view of an arrangement 1 g, which is similar to the arrangement 1f of Fig. 7. In contrast, the contactor or relay 3f is a monostable one and the arrangement 1g comprises a RS-flip-flop 15. The output of the RS-flip-flop 15 is fed to a control input of the monostable contactor or relay, i.e. to the actuating unit 11 . The external on terminal T11 is fed to a set input of the RS-flip-flop 15 and the output of the electronic threshold switch 9 is fed to a reset input of the RS-flip- flop 15 if the second switching contact S2 is closed in the energized state of the actuating unit 11 . If the second switching contact S2 is open in the energized state of the actuating unit 11 , the set input and the reset input change their roles. Accordingly, a pulse fed into T10 or T12 causes opening the monostable second switching contact S2, and a pulse fed into T11 causes closing the monostable second switching contact S2. It should be noted that the OR-gate 14 is just optional and may also be omitted. It should be noted that the contactor or relay 3g can also be used in combination with the circuit breakers 2a, 2b, 2d and 2e of Figs. 1 , 3, 5 and 6. Finally, it should also be noted that the RS-flip-flop 15 alternatively may be part of the circuit breaker 2g.

In the embodiments disclosed hereinbefore, the circuit breakers 2a..2g and the contactors or relays 3a..3g had separate housings 4 and 10. However, this is no necessary condition and Fig. 9 shows an arrangement 1 h, which equals the arrangement 1g of Fig. 8 but which has a common housing 16. Accordingly, the terminals T2, T4, T5, T6, T8 and T10 are omitted in this embodiment. The function of the arrangement 1 h however is the same as for the arrangement 1g. It should be noted that a common housing 16 may also be used for the arrangements 1 a..1 g of Figs. 1 to 7.

Fig. 10 shows a schematic view of an arrangement 1 i, which is similar to the arrangement 1 c of Fig. 4. In contrast, instead of the load current sensor 8b there is an additional residual current sensor 8a’. For example, the residual current sensor 8a may be embodied as a DC residual current sensor, and the additional residual current sensor 8a’ may be embodied as an AC residual current sensor. In this way, the first switching contact S1 is triggered by an AC residual current or a DC residual current, whereas the second switching contact S2 is triggered only by an DC residual current. This embodiment is particularly useful for charging stations for electric vehicles because electric vehicles primarily cause DC fault currents. As the cars move away again, also the reason for the DC fault current disappears. Hence, it is beneficial to clear such situations remotely. However, in an alternative embodiment, the AC residual current and the DC residual current may change their roles in the arrangement 1 i of Fig. 10.

Equivalently, Fig. 11 shows a schematic view of an arrangement 1 j, which is similar to the arrangement 1 d of Fig. 5. In contrast, instead of the residual current sensor 8a there is an additional load current sensor 8b’. For example, the load current sensor 8b may be embodied as a DC load current sensor, and the additional load current sensor 8b’ may be embodied as an AC load current sensor. In this way, the first switching contact S1 is triggered by an AC load current or a DC load current, whereas the second switching contact S2 only is triggered by an DC load current. This embodiment is particularly useful for charging stations for electric vehicles, too, because electric vehicles, if at all, primarily can cause excessive DC load currents. As the cars move away again, also the reason for the DC overload disappears. Hence, it is beneficial to clear such situations remotely. However, in an alternative embodiment, the AC load current and the DC load current may change their roles in the arrangement 1j of Fig. 11 .

It is noted that the invention is not limited to the embodiments disclosed hereinbefore, but combinations of the different variants are possible. In particular, additional and non-depicted variants of current sensors 8a..8b’ and their use are possible. Moreover, in reality, the system may have more or less parts than shown in the figures. Moreover, the description may comprise subject matter of further independent inventions.

It should also be noted that the term "comprising" does not exclude other elements and the use of articles "a" or "an" does not exclude a plurality. Also elements described in association with different embodiments may be combined. It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

LIST OF REFERENCE NUMERALS arrangement

2a..2j circuit breaker

3a..3j contactor or relay

4 circuit breaker housing

5 trigger unit

6 latch

7 handle

8a, 8a’ residual current sensor

8b, 8b’ load current sensor

9 electronic threshold switch

10 contactor or relay housing

11 actuating unit

12 thermal overload sensor

13 additional trigger unit

14 OR-function (OR-gate)

15 RS-flip-flop

16 common housing

CS current signal

CES current exceedance signal

NCS normal current signal

I current

ILI ..L3 current through phase

IN current through neutral line

L1..L3 phase

N neutral line

51 first switching contact

52 second switching contact

Ssi switching state of first switching contact

Ss2 switching state of second switching contact t time ti..te time points

T1..T12 terminal

TH1 first current threshold TH2 second current threshold

TH3 third current threshold