Residual current device and method for operating a residual current device

Abstract

A residual current device (1) has two operation states and comprises a residual current detection unit (2) configured to detect a residual current signal (20), a calculation unit (3) configured to calculate a corresponding charge (30) from the residual current signal (20), a threshold unit (4) configured to detect whether the charge (30) exceeds a predetermined threshold (40), and a tripping unit (5) configured to trip the residual current device (1) if an exceedance of the threshold (40) is detected by the threshold unit (4). In a first operation state (11) the tripping unit (5) is configured to be activated if a residual current is detected. In a second operation state (12) the tripping unit (5) is configured to be activated if an exceedance of the predetermined threshold (40) of charge (30) is detected by the threshold unit (4). The residual current device (1) comprises a state selector (8) configured to determine the operation state (11, 12). Furthermore, a method for operating a residual current device (1) is specified.

Description

[0001] Description

[0002] RES IDUAL CURRENT DEVICE AND METHOD FOR OPERATING A RES IDUAL CURRENT DEVICE

[0003] The present disclosure relates to a residual current device . The disclosure further relates to a method for operating a residual current device .

[0004] One obj ect to be achieved, inter alia, is to speci fy an improved residual current device that is in particular capable of tripping i f a charge exceeding a threshold is detected . A further obj ect to be achieved is to speci fy an improved method by which such a residual current device can be operated .

[0005] These obj ects are achieved, inter alia, by a residual current device comprising the features of independent claim 1 and by a method comprising the features of claim 12 , respectively . Advantageous embodiments and further developments are the subj ect of the dependent patent claims .

[0006] In at least one embodiment the residual current device comprises a residual current detection unit configured to detect a residual current signal . The residual current device further comprises a calculation unit configured to calculate a corresponding charge from the residual current signal . The residual current device further comprises a threshold unit configured to detect whether the charge corresponding to the residual current signal exceeds a predetermined threshold .

[0007] The residual current device further comprises a tripping unit configured to trip the residual current device i f an exceedance of the threshold is detected by the threshold unit . The residual current device comprises two operation states . In a first operation state the tripping unit is configured to be activated i f a residual current is detected . In a second operation state the tripping unit is configured to be activated i f an exceedance of the predetermined threshold of charge is detected by the threshold unit . The residual current device comprises a state selector configured to determine the operation state .

[0008] The residual current device may be configured to interrupt at least one powerline of an electrical system such as a circuit configuration i f a failure or another safety-relevant event is detected . For this purpose , the residual current device may comprise a switch that is opened in the case of a tripping event . The switch may be connected to the tripping unit and may be tripped by the tripping unit .

[0009] The residual current detection unit may comprise a current measurement device such as an amperemeter or preferably a current trans former, a fluxgate-magnetometer, one or more shunt devices , one or more Hall elements . Furthermore , the residual current detection unit may comprise a current trans former . The residual current detection unit is arranged in an electrical system such as a circuit configuration so that a residual current can be detected . The residual current detection unit is configured to provide the residual current signal as an output . Thus , the residual current detection unit functions as a data acquisition system .

[0010] The residual current signal may be provided as a digital signal or an analog signal , depending on the components following in a signal chain of the residual current device . Accordingly, the residual current detection unit may optionally comprise an analog-to-digital converter (AD converter ) .

[0011] The calculation unit may comprise an integrator to calculate the charge from the residual current signal by integration . Alternatively, the calculation unit may comprise a multiplicator to calculate the charge by multiplying the residual current signal by time . Here and in the following the term "time" in particular refers to a certain period of time characteristic of the residual current signal . I f , for example , the residual current signal comprises current pulses , the time is preferably a pulse duration .

[0012] The calculation unit comprises a microprocessor, for example . Additionally or alternatively, the calculation unit may comprise at least one analog circuit component . For example , the integrator may be implemented by a suitable capacitor or by an integration circuit using an operational ampli fier .

[0013] The calculation unit is configured to provide the charge corresponding to the residual current signal . Depending on the components of the calculation unit and the components following in the signal chain, the charge may be output as an analog or digital signal . Accordingly, the calculation unit may comprise an AD converter .

[0014] The threshold unit may comprise at least one comparator and at least one memory space . In the memory space the predetermined threshold is stored, preferably . The comparator is in particular configured to compare the charge provided by the calculation unit with the predetermined threshold . I f the charge exceeds the threshold, the threshold unit may provide a tripping signal for the tripping unit . The tripping unit is in particular configured to trip the residual current device upon receiving the tripping signal .

[0015] The threshold unit may comprise analog components . For example , the threshold unit comprises at least one operational ampli fier used as a comparator configured to compare the charge to the predetermined threshold .

[0016] Depending on the components of the threshold unit and / or the tripping unit , the tripping signal may be provided as a digital or analog signal . Accordingly, the threshold unit and / or the tripping unit may comprise an AD converter .

[0017] The calculation unit and the threshold unit may be integrated in a processing unit . The processing unit includes , for example , an integrated circuit , a micro integrated circuit (pIC ) , a microcontroller, a field programmable gate array ( FPGA) or a digital signal processor ( DSP ) . The processing unit is preferably configured to process digital signals . Therefore , the processing unit may be provided with digital data during operation or comprise an AD converter located at an input of the processing unit .

[0018] The residual current device described herein is based on the following technical considerations . In modern applications , where a lot of power electronics are used in electrical systems , residual currents may occur that are not sinusoidal . In contrast , residual current signals and residual currents comprising pulses , pulse trains and capacitor discharges may occur .

[0019] Common residual circuit devices use current based approaches to detect residual currents and potential safety-relevant situations . However, for short pulses , i . e . pulses of up to 10 ms pulse duration, the charge carried by the pulse is a convenient measure for biological cell stimulation . In particular, this concerns the stimulation of cells i f a human heart is not only responsible for the correct activation of the heart but also for pathological stimulation which leads to ventricular fibrillation . Thus , for safety purposes it is advantageous to use the charge as a dominating unit for short residual pulses .

[0020] The residual current device described herein makes use of the idea to provide a calculation unit , by which a charge corresponding to a residual current signal can be obtained . This charge may be used for comparing to a threshold to decide whether a safety-relevant event is present . The residual current device can then be tripped accordingly .

[0021] According to at least one embodiment of the residual current device , the calculation unit comprises an integrator configured to calculate the corresponding charge from the residual current signal by integration . In particular, the residual current signal is integrated over time . The time is preferably a certain period of time characteristic of the residual current signal . For example , i f the residual current signal comprises pulses , the time may be a pulse duration .

[0022] The integrator may be part of the processing unit and may be configured to carry out integration by using software . In this case , the integrator in particular processes digital data . Hence , the residual current signal is preferably a digital signal or is converted to a digital signal before integration . Alternatively, the integrator comprises an analog integration circuit configured to integrate the residual current signal . For example , the analog circuit comprises a capacitor, whose charge is increased during a certain time by the residual current signal . Preferably, the analog circuit component comprises an operational ampli fier configured as an integrator . Preferably, the analog circuit component receives the residual current signal as an analog signal .

[0023] According to at least one embodiment , the threshold unit comprises an analog threshold circuit component configured to generate the tripping signal for the tripping unit . For example , the analog circuit component comprises an operational ampli fier configured as a comparator . The operational ampli fier configured as the comparator is in particular configured to compare the charge received from the calculation unit with the predetermined threshold and provide the tripping signal accordingly . Preferably, the analog circuit component receives the charge as an analog signal .

[0024] According to at least one embodiment of the switching device , the residual current detection unit comprises a current trans former . Furthermore , the calculation unit is configured to classi fy the residual current signal . The calculation unit is further configured to assign a class value to the residual current signal according to the class of the residual current signal . The calculation unit is further configured to determine the corresponding charge by multiplying the class value by time .

[0025] For example , the residual current signal includes isolated peak pulses , pulse trains , rectangular pulses , a pulse-width modulation, capacitor discharges and other signal types . The calculation unit may be calibrated with di f ferent sorts of signal types of the residual current signal . The calibration can be carried out using an arti ficial intelligence (AT ) method . After calibration, the calculation unit may classi fy the signal types of the residual current signal and assign a class value to each class accordingly .

[0026] The class value is in particular multiplied by time to determine the corresponding charge . The multiplication by time may be necessary since certain signal types may only be safety relevant i f the residual current signal shows this signal type over a certain period of time . The time multiplication is carried out by a multiplicator , for example . The multiplicator is a software executed on the calculation unit , for example .

[0027] Hence , an integration of the residual current signal can be omitted by classi fying the residual current signal and assigning class values accordingly .

[0028] According to an alternative embodiment , the residual current device comprises a signal analyzing unit connected to the residual current detection unit and connected to an assignment unit . The assignment unit may be included in the calculation unit . The signal analyzing unit is configured to classi fy the residual current signal . The assignment unit is configured to assign a class value to the residual current signal according to a class of the residual current signal , and the calculation unit is configured to determine the corresponding charge by multiplying the class value by time . The signal analyzing unit may be distinct from the calculation unit . The signal analyzing unit is part of the processing unit , for example .

[0029] For example , the residual current signal includes isolated peak pulses , pulse trains , rectangular pulses , a pulse-width modulation, capacitor discharges and other signal types .

[0030] The signal analyzing unit is configured to identi fy the signal type and classi fy the residual current signal accordingly . In particular, classi fication is carried out by classi fication filters , a Fast Fourier Trans formation method, an Al method, or other suitable methods .

[0031] The assignment unit assigns the class value to the residual current signal according to the class provided by the signal analyzing unit . For example , the assignment unit receives the residual current signal and the class of the residual current signal as an input and provides the assigned class value as an output .

[0032] The class value is in particular multiplied by time to determine the corresponding charge . The multiplication by time may be necessary since certain signal types may only be safety relevant i f the residual current signal shows this signal type over a certain period of time . The time multiplication is carried out by a multiplicator , for example . The multiplicator is a software executed on the calculation unit , for example .

[0033] According to at least one embodiment of the residual current device comprising a signal analyzing unit , the residual current detection unit further comprises a shunt device . The shunt device is connected to the signal analyzing unit . Between the shunt device and the signal analyzing unit an adaptive ampli fier may be arranged .

[0034] The shunt device is preferably placed in a current-carrying conductor of a powerline of the electrical system . For example , each power line and a neutral line of the electrical system are provided with a shunt that is preferably part of the shunt device . The shunt device in particular provides the residual current signal to the signal analyzing unit .

[0035] The adaptive ampli fier is configured to ampli fy the residual current signal from the shunt device such that the signal analyzing unit is not overdriven .

[0036] The residual current device comprises two operation states . In a first operation state the tripping unit is configured to be activated i f a residual current is detected . In a second operation state the tripping unit is configured to be activated i f an exceedance of the predetermined threshold of charge is detected by the threshold unit . The residual current device comprises a state selector configured to determine the operation state .

[0037] The state selector may be integrated in the processing unit or may be an individual unit . For example , the state selector is a pIC, an FGPA or a microcontroller .

[0038] The state selector is in particular configured to analyze the residual current signal . I f the residual current signal has a signal type for which a charge-based operation principle of the residual current device is preferable , the second operation state is selected . This can be the case i f the signal type of the residual current signal signi ficantly deviates from a sinusoidal signal. For example, the signal type may be current pulses, pulse trains, rectangular pulses or the like.

[0039] If, in contrast, the signal type is sinusoidal, essentially sinusoidal, sinusoidal-like or similar to sinusoidal, the state selector may select the first operation state during operation. In this case the residual current device in particular works as a common residual current device.

[0040] Hence, a common current-based operation mode, i.e. first operation state, of the residual current device can be combined with a charge-based operation mode, i.e. second operation state, by providing the state selector. Thus, it is possible to have a voltage independent system as a backup.

[0041] According to at least one embodiment of the residual current device comprising a state selector, the residual current device comprises a first circuit configured to be operated in the first operation state. The residual current device comprises a second circuit configured to be operated in the second state. Preferably, the first circuit and the second circuit are separate at least in parts. For example, the first circuit corresponds to a common residual current device, and the second circuit corresponds to a circuit which can be operated in a charge-based operation mode, i.e. the second operation state. Advantageously, this allows to easily extend a common current-based residual current device by functionality of a charge-based operation mode.

[0042] It is possible that the first circuit and the second circuit are implemented in software, for example on individual microcontrollers. Alternatively, it is possible that the first circuit is formed by an electronic circuit and the second circuit is implemented in software , for example executed by the processing unit or the calculation unit together with the threshold unit .

[0043] According to at least one embodiment of the residual current device comprising a state selector, a common circuit is operated in a first and second operation state . The common circuit in particular comprises the processing unit including at least the calculation unit and the threshold unit . In particular, the processing unit is configured to operate in the first operation state or in the second operation state depending on a selection signal provided by the selector . The selector may be included in the processing unit .

[0044] The selector is in particular configured to provide the selection signal based on a signal analyzation of the residual current signal , for example as described above .

[0045] The two operation states are preferably implemented in software executed by the processing unit controlling the tripping unit . Hence , a relatively compact residual current device capable of operating in both operation states can advantageously be provided .

[0046] According to at least one embodiment , the residual current device further comprises a pulse analyzing unit configured to determine an intermediate time between adj acent pulses of the residual current signal as well as a height of the pulses . In particular, the pulse analyzing unit is configured to analyze residual current signals at least partially comprising pulses . Preferably, the pulse analyzing unit receives the residual current signal as an input . In particular, the residual current signal is received digitally processed by the pulse analyzing unit . The pulse analyzing unit is integrated in the processing unit , for example . It is possible that the pulse analyzing unit is implemented as software .

[0047] The residual current device preferably further comprises a weight unit configured to adapt the threshold according to the intermediate time and / or the height of the pulses by applying at least one weight factor . The weight unit is preferably connected to the pulse analyzing unit and receives signals from the pulse analyzing unit as an input . In particular, the weight unit is connected to the threshold unit , providing the weight factor to the threshold unit for adapting the threshold . In particular, the weight factor may be a multiplication factor . The weight factor may be frequency dependent , i . e . in particular dependent on a frequency of the residual current signal .

[0048] Since di f ferent signal types lead to di f ferent intensity of a stimulation of a human heart , certain signal type of the residual current signal can be particular safety relevant compared to other signal types . By applying weight factors to threshold, the threshold can be adapted to certain signal types . Thus , it can be ensured that particularly safetyrelevant signal types reliably trip the residual current device , increasing overall safety of the electrical system .

[0049] Furthermore , a method for operating a residual current device is speci fied . In particular a residual current device in accordance with one or more embodiments described herein can be operated by the method . Thus , all features disclosed for the method are also disclosed for the residual current device and vice versa .

[0050] In at least one embodiment the method for operating a residual current device comprises a step of detecting a residual current signal by the residual current detection unit . In a further step of the method a corresponding charge is calculated from the residual current signal by means of the calculation unit . In a further step of the method an exceedance of the corresponding charge above a predetermined threshold is detected by a threshold unit . In particular, the threshold unit determines whether the corresponding charge exceeds the predetermined threshold . In a further step of the method the residual current device is tripped by a tripping unit i f an exceedance of the predetermined threshold is detected .

[0051] In particular, the steps of the method are carried out in the recited order .

[0052] According to at least one embodiment of the method, the residual current signal is at least one converted from an analog signal to a digital signal or vice versa . For example , conversion is carried out by an AD converter or a digitalanalog converter ( DA converter ) . For example , certain units of the residual current device are configured to process digital or analog signals . Thus , the signals may be converted to carry out the method .

[0053] According to at least one embodiment of the method, the residual current signal is classi fied by assigning a class value to the residual current signal . In particular, the corresponding charge is calculated by multiplying the class value by time . The time is in particular a characteristic time of the residual current signal . For example , i f the residual current signal comprises pulses , the characteristic time may a pulse duration . Multiplying the class value by time is preferably carried out by a multiplicator . For example , the multiplicator is included in the calculation unit .

[0054] The calculation unit may comprise the assignment unit , by which the class value is assigned to the residual current signal according to the classi fication . The classi fication is in particular carried out by the signal analyzing unit connected to the assignment unit .

[0055] According to at least one embodiment of the method, the residual current device comprises two operation states . In the first operation state the tripping unit is activated i f a residual current is detected . In the second operation state the tripping unit is activated i f an exceedance of the predetermined threshold of charge is detected by the threshold unit . The operation state is in particular detected by the selector .

[0056] Further advantages and advantageous embodiments and further developments of the residual current device and the method described herein will become apparent from the following exemplary embodiments shown in connection with schematic drawings . Identical elements , elements of the same kind or elements having the same ef fect are provided with the same reference signs in the figures . The figures and the proportions of the elements shown in the figures are not to be regarded as true to scale . Rather, individual elements may be shown exaggeratedly large for better representability and / or for better comprehensibility .

[0057] In the figures :

[0058] Figure 1 shows a schematic representation of a residual current device described here according to a first exemplary embodiment ;

[0059] Figure 2 shows a schematic representation of an integrator used in the residual current device according to the first exemplary embodiment ;

[0060] Figures 3 and 4 show schematic representations of a residual current device described here according to a second exemplary embodiment ;

[0061] Figures 5 to 7 show schematic representations of a residual current device described here according to a further exemplary embodiment .

[0062] Figure 1 illustrates a residual current device 1 described herein according to a first exemplary embodiment . The residual current device 1 comprises a residual current detection unit 2 configured to detect a residual current signal 20 , in particular of an electrical system in which the residual current device 1 may be arranged . The residual current detection unit 2 comprises a current measurement device such as a current trans former, a fluxgatemagnetometer, a shunt device and / or a Hall element . The residual current detection unit 2 is arranged at a powerline of the electrical system such that a residual current flowing in the electrical system can be detected . The residual current device 1 further comprises a calculation unit 3 . The calculation unit 3 is configured to calculate a charge 30 corresponding to the residual current signal 20 . In the present embodiment the charge 30 is calculated by integrating the residual current signal 20 .

[0063] The residual current device 1 further comprises a threshold unit 4 configured to compare the charge 30 to a predetermined threshold 40 . I f the charge 30 is larger than the threshold 40 , the threshold unit 4 provides a tripping signal 50 to a tripping unit 5 . Upon receiving the tripping signal 50 the tripping unit 5 trips the residual current device 1 , for example by activating a switch 91 interrupting the powerline .

[0064] The calculation unit 3 and the threshold unit 4 may be integrated in a processing unit 10 . The processing unit 10 includes , for example , an integrated circuit , a micro integrated circuit (pIC ) , a microcontroller, a field programmable gate array ( FPGA) or a digital signal processor ( DSP ) .

[0065] I f the residual current signal 20 comprises short pulses , common residual current devices may not ensure suf ficient safety since for such pulses a charge carried by the pulse is a convenient measure for biological cell stimulation . The residual current device 1 provides a calculation unit 3 , by which a charge 30 corresponding to the residual current signal 20 can be obtained . This charge 30 is the property by which it is determined whether the residual current device 1 is tripped or not .

[0066] The calculation unit 3 comprises an analog integration circuit component 32 that includes an integrator 31 . The integrator comprises an operational ampli fier 33 with a negative input port and a positive input port . Parallel to the operational ampli fier 33 a second capacitor 36 and a resistor 37 are arranged that are connected to the negative input port and an output port of the operational ampli fier 33 . The positive input port of the operational ampli fier 33 is connected to ground .

[0067] Parallel to the operational ampli fier 33 a first capacitor 35 is arranged such that it is connected to the negative input port and the ground . The output port of the operational ampli fier 33 is connected to an analog-digital converter (AD converter ) 34 .

[0068] The analog integration circuit component 32 acts as an integrator . Thus , the residual current signal 20 can be integrated by using an analog circuit component . The integrated residual current signal is digiti zed by the AD converter 34 and output as a digital signal .

[0069] In contrast to the first exemplary embodiment , the residual current device 1 shown in Figures 3 and 4 comprises a signal analyzing unit 6 . The signal analyzing unit 6 is configured to classi fy the residual current signal 20 and is thus connected to the residual current detection unit 2 .

[0070] The residual current detection unit 2 comprises a shunt device 24 ( cf . Figure 4 ) which is connected to the signal analyzing unit 6 . The shunt device 24 is arranged in a current-carrying powerline 90 that may be interrupted by activating a switch 91 in a tripping event . The switch 91 can be activated by the tripping unit 5 . Between the shunt device 24 and the signal analyzing unit 6 an adaptive ampli fier 25 may optionally be arranged, by which an overdrive of the signal analyzing unit 6 can be prevented .

[0071] The signal analyzing unit 6 is a microcontroller or the like . The signal analyzing unit 6 is configured to classi fy the residual current signal 20 according to a signal type of the residual current signal 20 . For example , the residual current signal 20 includes isolated peak pulses , pulse trains , rectangular pulses , a pulse-width modulation, capacitor discharges and other signal types .

[0072] The signal analyzing unit 6 is connected to an assignment unit 7 of the processing unit 10 . It is also possible that the signal analyzing unit 6 is included in the processing unit 10 .

[0073] The assignment unit 7 assigns a class value 71...7N to the residual current signal 20 according to the class of the residual current signal 20 . This means that one class value 71...7N corresponds to each signal type known to the signal analyzing unit 6 .

[0074] The corresponding class value 71...7N is multiplied by time by a multiplicator 70 included in the calculation unit 3 . The time is a characteristic time of the residual current signal . The output of the multiplicator 70 is the corresponding charge 30 which is processed by the threshold unit 4 similar to the first exemplary embodiment . Hence , integrating the residual current signal 20 can be omitted .

[0075] In contrast to the residual current device 1 according to Figure 1 , the residual current device 1 shown in Figure 5 comprises two operational states 11 , 12 . In the first operation state 11 a first circuit 13 is operated . The first circuit 13 is configured to generate a tripping signal 50 for the tripping unit 5 i f a residual current is detected . Thus , the first circuit 13 operates similar to a common residual current device . In particular, in the first operation state 11 , the residual current device 1 operates in a current-based operation mode .

[0076] In the second operation state 12 a second circuit 14 is operated . The second circuit 14 comprises the processing unit

[0077] 10 , as for example described in connection with Figure 1 . However, it is also possible that the second circuit 14 functions similar to the residual current device 1 described in connection with Figure 2 . In particular, in the second operation state 12 , the residual current device 1 operates in a charge-based operation mode .

[0078] The first circuit 13 and the second circuit 14 are separated from each other and can be operated independently of each other . Thus , the first circuit 13 may form a backup for the second circuit 14 and vice versa .

[0079] In other aspects the exemplary embodiment according to Figure 5 is in particular similar in its features , ef fects and functionalities to the first exemplary embodiment .

[0080] In contrast to the residual current device 1 shown in Figure 5 , the residual current device 1 shown in Figure 6 comprises a common circuit 15 for both operation states 11 , 12 . The common circuit 15 comprises the processing unit 10 . The processing unit 10 is configured to be operated in both operation states . This means that the two operation states

[0081] 11 , 12 are in particular implemented as software executed on the processing unit 10 . In addition to the calculation unit 3 and the threshold unit 4 , which are operated in the second state 12 , the processing unit 10 comprises a residual current threshold unit 43 configured to provide a tripping signal 50 i f a residual current is detected to exceed a certain threshold .

[0082] In other aspects the exemplary embodiment according to Figure

[0083] 6 is in particular similar in its features , ef fects and functionalities to the first exemplary embodiment .

[0084] In contrast to the first exemplary embodiment , the residual current device 1 according to Figure 7 comprises a pulse analyzing unit 9 included in the processing unit 10 . I f the residual current signal 20 comprises pulses , the pulse analyzing unit 9 is configured to determine an intermediate time between adj acent pulses of the residual current signal 20 as well as a height of the pulses . Thus , the pulse analyzing unit 9 receives the residual current signal 20 as an input .

[0085] The pulse analyzing unit 9 is connected to a weight unit 41 that is configured to adapt the threshold 40 according to the intermediate time and / or the height of the pulses by applying at least one weight factor 42 .

[0086] In other aspects the exemplary embodiment according to Figure

[0087] 7 is in particular similar in its features , ef fects and functionalities to the first exemplary embodiment .

[0088] The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features , which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itsel f is not explicitly speci fied in the patent claims or exemplary embodiments .

[0089] References

[0090] 1 residual current device

[0091] 2 residual current detection unit

[0092] 3 calculation unit

[0093] 4 threshold unit

[0094] 5 tripping unit

[0095] 6 signal analyzing unit

[0096] 7 assignment unit

[0097] 8 selector

[0098] 9 pulse analyzing unit

[0099] 10 processing unit

[0100] 11 first operation state

[0101] 12 second operation state

[0102] 13 first circuit

[0103] 14 second circuit

[0104] 15 common circuit

[0105] 20 residual current signal

[0106] 23 class value

[0107] 24 shunt device

[0108] 25 adaptive ampli fier

[0109] 30 charge

[0110] 31 integrator

[0111] 32 analog integration circuit component

[0112] 33 operational ampli fier

[0113] 34 AD converter

[0114] 35 first capacitor

[0115] 36 second capacitor

[0116] 37 resistor

[0117] 40 threshold

[0118] 41 weight unit

[0119] 42 weight factor

[0120] 43 residual current threshold unit 50 tripping signal

[0121] 70 multiplicator

[0122] 71...7N class value

[0123] 80 selection signal 90 powerline

[0124] 91 switch

Claims

Claims1. Residual current device (1) comprising- a residual current detection unit (2) configured to detect a residual current signal (20) ,- a calculation unit (3) configured to calculate a corresponding charge (30) from the residual current signal (20) ,- a threshold unit (4) configured to detect whether the charge (30) exceeds a predetermined threshold (40) , and- a tripping unit (5) configured to trip the residual current device (1) if an exceedance of the threshold (40) is detected by the threshold unit (4) , wherein the residual current device (1) comprises two operation states (11, 12) , and- in a first operation state (11) the tripping unit (5) is configured to be activated if a residual current is detected,- in a second operation state (12) the tripping unit (5) is configured to be activated if an exceedance of the predetermined threshold (40) of charge (30) is detected by the threshold unit (4) , and- the residual current device (1) comprises a state selector (8) configured to determine the operation state (11, 12) .

2. Residual current device (1) according to claim 1, wherein the calculation unit (3) comprises an integrator (31) configured to calculate the corresponding charge (30) from the residual current signal (20) by means of integration.

3. Residual current device (1) according to claim 2, wherein the integrator (31) comprises an analog integration circuit (32) configured to integrate the residual current signal (20) .

4. Residual current device (1) according to one of the preceding claims, wherein the threshold unit (4) comprises an analog threshold circuit component configured to generate a tripping signal (50) for the tripping unit (5) .

5. Residual current device (1) according to one of the preceding claims, wherein the residual current detection unit (2) comprises a current transformer, and the calculation unit (3) is configured- to classify the residual current signal (20) ,- to assign a class value (71...7N) to the residual current signal (20) according to the class of the residual current signal (20) , and- to determine the corresponding charge (30) by multiplying the class value (71...7N) by time.

6. Residual current device (1) according to one of claims 1 to 4, further comprising a signal analyzing unit (6) connected to the residual current detection unit (2) and an assignment unit (7) included in the calculation unit (3) , wherein- the signal analyzing unit (6) is configured to classify the residual current signal (20) ,- the assignment unit (7) is configured to assign a class value (71...7N) to the residual current signal (20) according to a class of the residual current signal (20) , and- the calculation unit (3) is configured to determine the corresponding charge (30) by multiplying the class value (71...7N) by time.

7. Residual current device (1) according to claim 6, wherein the residual current detection unit (2) comprises ashunt device (24) connected to the signal analyzing unit (6) , and an adaptive amplifier (25) is arranged between the shunt device (24) and the signal analyzing unit (6) .

8. Residual current device (1) according to one of the preceding claims, wherein a first circuit (13) is configured to be operated in the first operation state (11) and a second circuit (14) is configured to be operated in the second operation state (12) , wherein the first circuit (13) is separated from the second circuit (14) at least in parts.

9. Residual current device (1) according to one of the preceding claims, wherein in the first and second operation states (11, 12) a common circuit (15) is operated, wherein the common circuit (15) comprises a processing unit (10) including at least the calculation unit (3) and the threshold unit (4) , wherein the processing unit (10) is configured to operate in the first operation state (11) or in the second operation state (12) depending on a selection signal (80) provided by the selector (8) .

10. Residual current device (1) according to one of the preceding claims, further comprising- a pulse analyzing unit (9) configured to determine an intermediate time between adjacent pulses of the residual current signal (20) and a height of the pulses,- a weight unit (41) configured to adapt the threshold (40) according to the intermediate time and / or the height of the pulses by applying at least one weight factor (42) .

11. Method for operating a residual current device (1) comprising two operation states (12, 12) , the method comprising the steps of:- detecting a residual current signal (20) by a residual current detection unit (2) ;- obtaining a corresponding charge (30) from the residual current signal (20) by a calculation unit (3) ;- detecting whether the charge (30) exceeds a predetermined threshold (40) by a threshold unit (4) ;- tripping the residual current device by a tripping unit (5) if an exceedance of the predetermined threshold (40) is detected wherein- in a first operation state (11) the tripping unit (5) is activated if a residual current is detected,- in a second operation state (12) the tripping unit (5) is activated if an exceedance of the predetermined threshold (40) of charge (30) is detected by the threshold unit (4) , and- the operation state (11, 12) is determined by a selector(8) .

12. Method according to claim 11, wherein the residual current signal (20) is classified by assigning a class value (71...7N) , and the corresponding charge (30) is calculated by multiplying the class value (71...7N) by time.

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