Residual Current Circuit Breaker

Abstract

The present invention relates to a residual current circuit breaker (RCCB) (100) for an electric circuit (300). The RCCB comprises a first switching device (106) and a second switching device (140) connected in series between a power source (302) and a load (304). The first switching device (106) is configured such that the value of the current i supplied to the load (304) is equal to the switching current i of the first switching device (106). s The first switching device (140) is configured to switch to an OFF mode, in which no current is supplied to the load (304), when it detects that the residual current i is greater than 1 / 2. The second switching device (140) is configured to switch to an ON mode, in which the load (304) is short-circuited, when it detects a leakage of the current i supplied to the load (304). This provides a new RCCB architecture. When a leakage current is detected, a short circuit is introduced, i.e., the voltage at the load becomes zero and no person is harmed by the current in the circuit. However, when the load is short-circuited, a current rush occurs in the circuit, which triggers the first switching device to interrupt the circuit, and thereafter no current flows in the circuit. The present invention also relates to a circuit including such a residual current circuit breaker and a corresponding method.

Description

[Technical Field]

[0001] The present invention relates to a residual current circuit breaker for an electric circuit. The present invention also relates to a circuit comprising such a residual current circuit breaker and a corresponding method. [Background technology]

[0002] Residual current circuit breakers (RCCBs) or residual current devices (RCDs) are well known in the art. Other terms for devices with corresponding functions are earth fault circuit interrupters, earth fault interrupters, appliance leakage current interrupters, and leakage current detection interrupters.

[0003] The purpose of devices such as RCCBs and RCDs is to quickly interrupt or disconnect an electrical circuit to prevent harm to personnel from electric shock when there is an imbalance in current between the supply and return conductors. Any difference in current between the supply and return conductors indicates a leakage current which creates a risk of electric shock.

[0004] RCCBs and RCDs are typically testable and resettable devices: a mechanical input such as a test button creates a small leakage condition, and a reset button reconnects the conductors after the fault condition has been cleared. Summary of the Invention [Means for solving the problem]

[0005] It is an object of embodiments of the present invention to provide a solution that mitigates or overcomes the drawbacks and problems of conventional solutions.

[0006] These and further objects are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

[0007] According to a first aspect of the present invention, the above and other objects are achieved by providing a residual current circuit breaker (RCCB) for an electric circuit, the circuit being configured to be coupled between a power source and a load of the circuit, the circuit comprising a first switching device and a second switching device coupled in series with each other between the power source and the load; The first switching device is configured to supply a current i to the load at a value equal to the switching current i of the first switching device. s and when it detects that the load voltage is greater than The second switching device is configured to switch to an ON mode in which the load is short-circuited when a leakage of the current i supplied to the load is detected. This is achieved by the RCCB.

[0008] The switching current of the first switching device, i s is the current at which the first switching device switches from ON mode to OFF mode. The switching current may be, for example, a threshold current value. In one implementation, the switching current may be dynamically changed to an appropriate value depending on the application. The dynamic change in the switching current may be controlled by a software solution, a hardware solution, or a combination of software and hardware, for example, through one or more control devices. In an embodiment, the first switching device may be a transistor, such as a field effect transistor (FET), which means that the switching time is much faster than the switching time of a mechanical switch.

[0009] The RCCB according to the first aspect provides a new RCCB architecture. When a fault current is detected, a short circuit is introduced into the circuit by the second switching device, thus short-circuiting the load. This means that the voltage at the load becomes zero and no people are harmed by the current in the circuit. However, when the load is short-circuited, a current rush occurs in the circuit, which triggers the first switching device to interrupt the circuit, after which no current flows in the circuit. The current during the current rush is higher than the switching current of the first switching device, so the first switching device interrupts the circuit. The interruption of the circuit also means that no people are harmed because no current flows in the circuit after the circuit is interrupted.

[0010] In one implementation of the RCCB according to the first aspect, the second switching device is coupled in parallel with the load.

[0011] In one implementation of the RCCB according to the first aspect, the second switching device comprises an electronic switch coupled in parallel with the mechanical switch.

[0012] The electronic switch may be a transistor, for example a field effect transistor (FET), which means that the switching time is much faster than that of a mechanical switch.

[0013] This allows the electronic switch to switch quickly enough to prevent harm to personnel, whereas the mechanical switch meets regulatory requirements set by, for example, national laws and government agencies.

[0014] In one implementation of the RCCB according to the first aspect, The electronic switch is configured to switch to an ON mode in which the load is short-circuited when it detects a leakage of the current i supplied to the load, and at the same time The mechanical switch is configured to switch to an ON mode in which the load is short-circuited upon detecting a leakage of the current i supplied to the load.

[0015] In one implementation of the RCCB according to the first aspect, the electronic switch is configured to switch back to the OFF mode after a period of time T in which the load is not shorted.

[0016] In one implementation of the RCCB according to the first aspect, the period T is greater than the ON switching time of the mechanical switch, the ON switching time being the period for the mechanical switch to switch to ON mode.

[0017] This allows the mechanical switch time to switch to the ON mode before the electronic switch switches back to the OFF mode.

[0018] In one implementation of the RCCB according to the first aspect, the mechanical switch is configured to switch back to an OFF mode in which the load is not shorted upon receiving a user input.

[0019] The user may be the person operating the RCCB, which may meet regulatory requirements.

[0020] In one implementation of the RCCB according to the first aspect, the RCCB comprises: measuring a first current i1 at a first node of the circuit; measuring a second current i2 at a second node in the circuit; Detecting leakage of current i supplied to a load based on first current i1 and second current i2 The present invention is provided with a ground fault detector configured as follows.

[0021] In one implementation of the RCCB according to the first aspect, when detecting leakage of the current i supplied to the load, it is detected that the first current i1 and the second current i2 have different values.

[0022] The first current i1 and the second current i2 having different values may mean that the difference is less than a threshold. It should also be noted that time aspects may have to be taken into account when detecting a ground fault. For example, the measured current value used to detect a current leak may be integrated over a suitable period of time, such as an average value over that period.

[0023] In one implementation of the RCCB according to the first aspect, the first node is provided at the supply connector of the load and the second node is provided at the return connector of the load.

[0024] In one implementation of the RCCB according to the first aspect, the earth leakage detector is configured to detect DC and / or AC leakage.

[0025] In one implementation of the RCCB according to the first aspect, the earth leakage detector is a Hall sensor.

[0026] In one implementation of the RCCB according to the first aspect, the RCCB comprises at least one control device configured to control at least one of the first switching device and the second switching device.

[0027] The at least one control device may be either a software solution, a hardware solution or a combination of software and hardware. For example, as a software solution the control means may be implemented in a microcontroller, while in a hardware solution the control means may be implemented in a physical logic circuit. The at least one control device may be coupled to a leakage detector to receive an indication of leakage and / or absence of leakage of current in the circuit.

[0028] In one implementation of the RCCB according to the first aspect, the first switching device comprises: a) After a first time interval T1, the load switches from OFF mode back to ON mode, where current i is supplied to the load. It is configured as follows.

[0029] The switching time of the first switching device can be considered, for example, as the time from when a switching current of the transistor is detected until the transistor is set to OFF mode (no longer conducting). The switching time can be the sum of the detection time of the overcurrent (reaching a hardware limit) plus the switching time of the transistor to OFF mode. For example, the switching time of the first switching device can be 250 ns or less. The switching time of a conventional circuit breaker can be greater than 1 ms. Therefore, the switching time of the first switching device is always shorter than the switching time of a conventional circuit breaker, which also means that this circuit breaker is faster than a conventional circuit breaker.

[0030] The advantage of this implementation is that the switching means switches back from OFF mode to ON mode after the first time interval T1, so that in the event of a short duration overcurrent condition, e.g. inrush current, the circuit automatically operates in normal mode, i.e. the load operates properly.

[0031] In one implementation of the RCCB according to the first aspect, the first switching device comprises: b) The value of the current i supplied to the load is the switching current i s When it detects that the power is greater than Repeat steps a) and b) N times, where N is a positive integer. It is configured as follows.

[0032] This allows it to handle a number of consecutive inrush current instances in the AC case, and capacitive loads in the DC case.

[0033] In one implementation of the RCCB according to the first aspect, the first switching device comprises: Steps a) and b) are repeated N times, and then remain in the OFF mode during a second time interval T2. It is configured as follows.

[0034] In one implementation of the RCCB according to the first aspect, the second time interval T2 is greater than the first time interval T1.

[0035] According to a second aspect of the present invention, the above and other objects are achieved by an electric circuit comprising a power supply arranged to supply current to at least one load, and an RCCB according to any one of the preceding claims, the RCCB being coupled between the power supply and the at least one load.

[0036] According to a third aspect of the present invention, the above and other objects are achieved by a method for a RCCB, the RCCB being configured to be coupled between a power source and a load of a circuit, the RCCB comprising a first switching device and a second switching device coupled in series with each other between the power source and the load, the method comprising: The value of the current i supplied to the load is the switching current i of the first switching device. s switching the first switching device to an OFF mode in which no current is supplied to the load when detecting that the load is greater than when detecting a leakage of the current i supplied to the load, switching the second switching device to an ON mode in which the load is short-circuited; This is achieved by a method comprising:

[0037] The method according to the third aspect can be extended to a corresponding implementation of the RCCB embodiment according to the first aspect, whereby the implementation of the method comprises one or more features of the corresponding implementation of the RCCB.

[0038] The advantages of the method according to the third aspect are the same as those of the corresponding implementation of the RCCB according to the first aspect.

[0039] In one implementation of the method according to the third aspect, the method comprises: continuously measuring or monitoring the current delivered by the power supply to the load; Includes.

[0040] In an embodiment of the present invention, the current is monitored using a current monitoring means.

[0041] In one implementation of the method according to the third aspect, the method comprises: checking whether the measured current is higher than the threshold current of the first switching device, i.e. the switching current of the first switching device; Includes.

[0042] In one implementation of the method according to the third aspect, the method comprises: when determining that the measured current is higher than the threshold current of the first switching device, checking whether a maximum number n of consecutive overcurrent (e.g., inrush current) detections has been reached, where n is a counter value indicating the number of consecutive overcurrent detections. Includes.

[0043] In one implementation of the method according to the third aspect, the method comprises: interrupting the circuit by the first switching device for a first time interval T1 when it is determined that the maximum number of consecutive overcurrent detections has not been reached, and then switching back to the ON mode. Includes.

[0044] In one implementation of the method according to the third aspect, the method comprises: interrupting the circuit by the first switching device for a second time interval T2 when it is determined that the maximum number of consecutive overcurrent detections has been reached, where T2 is greater than T1, i.e., T2>T1; Includes.

[0045] In one implementation of the method according to the third aspect, the value of T2 depends on the application of the RCCB.

[0046] In one implementation of the method according to the third aspect, T2 is 5 s or less.

[0047] Further applications and advantages of embodiments of the present invention will become apparent from the following detailed description.

[0048] The accompanying drawings are intended to clarify and explain various embodiments of the present invention. [Brief explanation of the drawings]

[0049] [Figure 1] 1 illustrates an RCCB according to one embodiment of the present invention. [Figure 2] 1 illustrates a method according to one embodiment of the present invention. [Figure 3a] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 3b] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 4a] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 4b] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 5a] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 5b] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 6a] 1 illustrates a second switching device according to an embodiment of the present invention. [Figure 6b] Indicates the OFF and ON modes of the switch. [Figure 7] 1 shows an RCCB according to a further embodiment of the present invention. [Figure 8] 1 shows the relationship between switching time and rated current. [Figure 9] 10 shows a flowchart of a method for a first switching device. DETAILED DESCRIPTION OF THE INVENTION

[0050] 1 shows an RCCB 100 according to one embodiment of the present invention. According to this embodiment, the RCCB 100 is configured to be coupled between a power source 302 and a load 304 of a circuit 300, see for example FIGS. 3a, 3b, 4a, 4b, 5a and 5b. The RCCB 100 comprises a first switching device 106 and a second switching device 140 coupled in series with each other between the power source 302 and the load 304. The first switching device 106 is configured to have a switching current i of the first switching device 106 such that the value of the current i supplied to the load 304 is equal to the value of the switching current i of the first switching device 106. s The second switching device 140 is configured to switch to an OFF mode in which no current is supplied to the load 304 when it detects that the current i supplied to the load 304 is greater than 1. The second switching device 140 is configured to switch to an ON mode in which the load 304 is short-circuited when it detects that the current i supplied to the load 304 is leaking.

[0051] 2 illustrates a corresponding method according to one embodiment of the present invention that may be implemented in an RCCB 100 such as the one shown in FIG. 1. The method 200 is configured such that the first switching device 106 detects a value of the current i supplied to the load 304 as the switching current i of the first switching device 106. s The method 200 includes step 202 of switching the first switching device 106 to an OFF mode in which no current is supplied to the load 304 upon detecting a leakage of the current i supplied to the load 304, wherein the second switching device 140 is switched to an ON mode in which the load 304 is shorted upon detecting a leakage of the current i supplied to the load 304.

[0052] In general, in the present disclosure, a switch or switching means or device may be understood as being capable of having an ON mode and an OFF mode, as shown in Figure 6b. In the ON mode, the switch is closed so that current can flow / pass through the switch, and thus the switch is conducting. In the OFF mode, the switch is open so that current cannot flow / pass through the switch.

[0053] Figures 3a and 3b show an RCCB 100 according to a further embodiment of the present invention. Figure 3a shows a non-shorting mode of operation of the RCCB 100, and Figure 3b shows a short-circuit mode of operation of the RCCB 100. In the non-shorting mode of operation, the load 304 is not short-circuited, whereas in the short-circuit mode of operation, the load 304 is short-circuited.

[0054] Referring to FIG. 3a, an RCCB 100 according to the present invention is coupled between a power source 302 and a load 304 and is part of a circuit 300. The power source 302 may supply or deliver alternating current (AC) or direct current (DC) to the load 304, depending on the application. While only one load 304 is shown, it is understood that one or more loads may be part of the circuit 300 and may be supplied with either AC or DC current. Also shown are a first switching device 106 and a second switching device 140 coupled in series with each other between the power source 302 and the load 304 as shown. Also shown are a supply conductor SC and a return conductor RC of the load 304. The supply conductor SC and return conductor RC relate to the flow and direction of current in the circuit to and from the load 304. In an embodiment, the second switching device 140 is coupled in parallel with the load 304 as shown.

[0055] 3a, the RCCB 100 further includes a control device 104 configured to control the first switching device 106 and the second switching device 140 via control lines 162, indicated by dashed arrows, from the control device 104 to the first switching device 106 and the second switching device 140, respectively. Furthermore, a ground fault detector 150 is included in or is part of the RCCB 100. The ground fault detector 150 is configured to measure a first current i1 at a first node N1 of the circuit 300 and is further configured to measure a second current i2 at a second node N2 of the circuit 300. The ground fault detector 150 can detect leakage of the current i supplied to the load 304 based on the first current i1 and the second current i2. The first node N1 and the second node N2 may be located on opposite sides of the load 304 in relation to the direction of flow of the current i, as shown.

[0056] In an embodiment, detecting leakage of the current i supplied to the load 304 includes detecting that the first current i1 and the second current i2 have substantially different values. A very small difference between the first current i1 and the first current i2 may be due to, for example, measurement failure, hardware limitations, etc., without concluding that there is current leakage. The reason for such an error may be due to, for example, measurement error, hardware limitations, etc. Therefore, a detection interval and / or threshold may be used in this regard. For example, if the measured difference is less than the threshold, it is determined that there is no current leakage, while if the measured difference is greater than the threshold, it is determined that there is current leakage. Also, since the value may vary over time, the time aspect may have to be taken into account. In this case, an integration over an appropriate period may be performed to obtain a value used to determine whether there is current leakage in the circuit.

[0057] The ground fault detector 150 may be configured to detect both DC and AC leakage, and thus in an embodiment, the ground fault detector 150 is a Hall sensor.

[0058] Furthermore, the ground fault detector 150 is coupled to the control device 104 via a communication line 164, as indicated by the arrow from the ground fault detector 150 to the control device 104. When the ground fault detector 150 detects a current leakage, the ground fault detector 150 indicates this to the control device 104 via the communication line 164. For example, a control signal may be transmitted to the control device 104. It is further noted that the ground fault detector 150 may also be configured to indicate when there is no current leakage, for example, when the first current i1 and the first current i2 have substantially the same value. Also, in this case, an interval and / or a threshold and / or an integration may be used to determine whether there is currently no current leakage.

[0059] When no current leakage is detected, the circuit 300 functions in normal operation, with current i being supplied from the power supply 302 to the load 304 as shown in Figure 3a. Thus, no current passes through the second switching device 140, as indicated by the dashed lines into and out of the second switching device 140.

[0060] However, referring to FIG. 3b, when a leakage current is detected in circuit 300 by leakage current detector 150, an indication of the leakage current is sent to control device 104. Upon receiving the indication of a leakage current in circuit 300, control device 104 appropriately controls first switching device 106 and second switching device 140 via control coupling 162. Thus, control device 104 switches first switching device 106 to a first switching device 106 OFF mode, in which no current is supplied to load 304. Furthermore, control device 104 switches second switching device 140 to a second switching device 140 ON mode, in which load 304 is shorted. This means that current i in circuit 300 flows directly through second switching device 140 instead of through load 304, as shown in FIG. 3b. Thus, in this case, no current flows through load 304.

[0061] Figures 4a and 4b show an RCCB 100 according to a further embodiment of the present invention. Figure 4a shows the non-shorting mode, and Figure 4b shows the short-circuit mode, respectively. The main difference between the embodiment shown in Figures 3a and 3b and the embodiment shown in Figures 4a and 4b is that in the latter embodiment, the RCCB 100 comprises two independent control devices, namely 104 and 104', instead of one control device. The first control device 104 is coupled to and configured to control the first switching device 106, and the second control device 104' is coupled to and configured to control the second switching device 140. As shown in Figures 4a and 4b, the second control device 104' is also coupled to the ground fault detector 150 via a communication line 164. Thus, the interaction between the second control device 104' and the ground fault detector 150 may be as described above with reference to Figures 3a and 3b.

[0062] The first controlling device 104, in turn, may be coupled to an overcurrent detection device (see FIG. 7) via suitable communication lines 166 indicated by arrows. When an overcurrent is detected and indicated to the first controlling device 104, the first switching device 106 is controlled to interrupt the circuit 300. Further details regarding this embodiment are disclosed with reference to FIG. 7 below, in which the first controlling device 104 is an integral part of the first switching device 106.

[0063] 5a and 5b show an RCCB 100 according to a further embodiment of the present invention. FIG. 5a shows the non-shorting mode, and FIG. 5b shows the shorting mode, respectively. The difference between the embodiment shown in FIGS. 5a and 5b and the previous embodiments of FIGS. 3a, 3b, 4a and 4b is that the first switching device 106 in this case is a mechanical switch and / or a fuse. Therefore, no control device is required to control the first switching device 106. In the case of a mechanical switch, said mechanical switch may function and be configured as the mechanical switch of the second switching device 140 described with reference to FIG. 6a in the following disclosure, i.e., partially operated by a user 500.

[0064] FIG. 6a also illustrates a second switching device 140 according to an embodiment of the present invention. In this embodiment, the second switching device 140 comprises an electronic switch 142 coupled in parallel with a mechanical switch 144. During operation, the electronic switch 142 is configured to switch to an ON mode in which the load 304 is shorted by the electronic switch 142 upon detecting a leakage of the current i supplied to the load 304. Concurrently, the mechanical switch 144 is configured to switch to an ON mode in which the load 304 is shorted by the mechanical switch 144 upon detecting a leakage of the current i supplied to the load 304. In an embodiment, the ON switching of the electronic switch 142 and / or the mechanical switch 144 may be controlled by the control device 104, 104′ as described above. The operation of the electronic switch 142 and the mechanical switch 144 in the OFF mode and ON mode is illustrated in FIG. 6b.

[0065] Because the electronic switch 142 has a much shorter switching time than the mechanical switch 144, the electronic switch 142 is configured in an embodiment to switch back to the OFF mode after a period T in which the load 304 is not shorted by the electronic switch 142. The mentioned period T is designed to be greater than the ON switching time of the mechanical switch 144. The ON switching time of the mechanical switch 144 is the period for the mechanical switch 144 to switch from the OFF mode to the ON mode.

[0066] 6a, the mechanical switch 144 is configured in an embodiment to switch back to an OFF mode in which the load 304 is no longer shorted by the mechanical switch 144 upon receiving an input from a user 500, for example a person operating the RCCB 100. The input can be by a mechanical input means 400, for example a lever, button or switch, that resets the mechanical switch 144 from the ON mode back to the OFF mode. Thus, according to this embodiment, the mechanical switch 144 must be reset by the user 500 of the RCCB 100.

[0067] Meanwhile, the electronic switch 142 of the second switching device 140 may continue to be controlled by the control device 104, 104′ such that whenever the control device 104, 104′ gets an indication of a leakage current in the circuit, the electronic switch 142 is switched to the ON mode, and consequently, whenever the control device 104, 104′ gets an indication of no leakage current in the circuit 300, the electronic switch 142 is switched back to the OFF mode, i.e., the load 304 is no longer shorted by the electronic switch 142. However, the load 304 continues to be shorted by the mechanical switch 144 unless the mechanical switch 144 is reset.

[0068] FIG. 7 illustrates an embodiment of the present invention in which the first switching device 106 is part of a circuit breaker that is part of the RCCB 100 when operating in a non-shorting mode. The circuit breaker is configured to interrupt the electrical circuit 300 so that current cannot reach the electrical load 304. Thus, as previously described, the electrical circuit 300 includes at least one power source 302 configured to provide a current i (or a corresponding voltage) to at least one load 304, i.e., the power source 302 is electrically coupled to the load 304. Examples of loads 304 include, but are not limited to, household appliances. Thus, a load in this context refers to an electrical device configured to consume power for its operation. The power source 302 may be configured to provide AC or DC power, depending on the application. The provided current may be, for example, a mains current with a nominal voltage of 110V or 220V and a frequency of 50Hz. However, the present invention is not limited thereto, and thus embodiments of the present invention may be applied to all types of voltage systems, from low-voltage systems to high-voltage systems.

[0069] When the circuit breaker interrupts the circuit 300, the current i cannot reach the load 304. In this respect, the circuit breaker comprises a first switching device 106 arranged to be controlled by a control means 104. The first switching device 106 is arranged to switch between an ON mode, in which the current i from the power source 302 is supplied to the load 304, and an OFF mode, in which no current is supplied to the load 304. The first switching device 106 thus acts as a switch to open or close the circuit. The control means 104 can be, for example, but not limited to, the digital microcontroller mentioned above.

[0070] The control means 104 may be configured to obtain a value of the current provided by the power source and supplied to the load 304, and based on the obtained value of the current the control means 104 controls the first switching device 106 accordingly. In particular, the control means 104 herein may be configured to: a) determine whether the value of the current i is equal to the switching current i of the circuit breaker; sand a) switching the first switching device 106 from the OFF mode back to the ON mode after a first time interval T1 if the first switching device 106 is greater than T1 within a switching time of the circuit breaker.

[0071] The control means 104 may be further configured to repeat steps a) and b) N times, where N is a positive integer, such that the current i supplied to the load 304 during one of the repetitions is equal to the switching current i of the circuit breaker. s If the switching means is kept in ON mode,

[0072] 7 , the circuit breaker comprises a current monitoring means 108 configured to continuously monitor the current i supplied from the power source 302 to the load 304 and to provide the value of the monitored current i to the control means 104 via the threshold detector 110 through signal couplings 120 and 122. The monitoring may be performed by the current monitoring means 108 configured to continuously measure the current supplied by the power source and to provide the current measurement to the threshold detector 110. In the threshold detector 110, both the switching current and the breaking current may be checked. If the measurement value is greater than the switching current threshold, the threshold detector 110 triggers the control means 104 through the signal coupling 128, which in turn switches the first switching device 106 from the ON mode to the OFF mode through the control interface 118. Thus, the threshold detector 110 is configured to trigger the control means 104 if the current measurement value is greater than the switching current of the circuit breaker 100. However, if the measured current is greater than the interrupting current of the circuit breaker, the control means 104 immediately switches the first switching device 106 to the OFF mode to prevent harm to components within the circuit breaker.

[0073] The current monitoring means 108 may be an inductor, such as a coil as shown in FIG. 7. The function of this coil is to delay an overcurrent so that the switching means can be set to OFF mode before the electrical components are damaged. The coil has two measurement nodes 134 and 136 provided on different sides of the inductive section of the coil. Thus, in this embodiment, both a zero-crossing detector 116 and a threshold detector 110 are provided to measure the current at the measurement nodes 134 and 136 of the coil. In other words, the current monitoring means 108, or in this case the coil, is connected to the zero-crossing detector 116 via a coupling 120 to the measurement node 134 and a coupling 122 to the measurement node 136. Herein, the zero-crossing detector 116 is configured to detect zero-crossings when the current supplied from the power supply 302 is AC. Thus, the zero-crossing detector 116 indicates zero-crossings to the control means 104 via a signaling means 126 so that the control means 104 can switch the switching means back to ON mode at the zero-crossings. This means that the zero crossing detector 116 is only relevant in the AC case.

[0074] 7 also shows a delay block 114 provided to provide the correct time delay to the control means 104 through the signaling means 132. For example, in the case of DC, the first time interval T1 is longer than the threshold time interval which defines when the current monitoring means 108 has lost substantially all of its stored energy in an embodiment of the present invention. Thus, in this case, the first time interval T1 may be provided as a delay to the control means by the delay block 114. Thus, the threshold detector 110 may trigger or inform the delay block 114 through the signaling means 130.

[0075] As also shown in FIG. 7 , the circuit breaker 100 is coupled in series with another, second circuit breaker 112, and the circuit breaker 100 and the second circuit breaker 112 are coupled together between the power source 302 and the load 304. In embodiments, the second circuit breaker 112 is a so-called standardized circuit breaker, such as a fuse, a two-pole or four-pole miniature circuit breaker, or any other suitable standardized circuit breaker. An example of a circuit breaker standard is IEC 60898-1. A standardized second circuit breaker allows the circuit breaker to meet safety requirements for electrical safety set by national, regional, and international governmental agencies and organizations. According to these embodiments, the switching time of the first switching device 106 is shorter than the switching time of the second circuit breaker 112.

[0076] In a further embodiment of the present invention, the breaking or switching current of the first switching device 106 is greater than the breaking current of the second circuit breaker 112. The breaking or switching current of the first switching device 106 is, in embodiments, at least three times higher than the breaking current of the second circuit breaker 112. In a digital circuit breaker, the ability of the transistor (the switch of the circuit breaker, i.e., switching 106 in this case) to handle the peak current sets a hardware limit for the breaking current. The breaking current of the first switching device 106 may be considered a hardware limit set to protect the switching means, such as the transistor acting as a switch, from overcurrent. The breaking current of the second circuit breaker 112 may be the rated current of the second circuit breaker 112.

[0077] Additionally, the second circuit breaker 112 may be integrated with the RCCB, for example, in the same housing and / or on a common PCB. In one case, a metal strip corresponding to a fuse is provided in the common PCB and serves as the second circuit breaker 112. The metal strip may correspond to a thermal trigger of a miniature circuit breaker (MCB).

[0078] Figure 8 illustrates the relationship between switching time and rated current. The x-axis shows the rated current ('x' x a given nominal value) and the y-axis shows the switching time in seconds. The magnetic trigger zones, marked B, C and D in Figure 8, relate to different normalized rated overcurrents of the MCB, while the thermal trigger zones relate to the heat generated by the energy generated in the MCB (i.e., current * time).

[0079] The vertical lines labeled "Switching Current Threshold" demarcate Zones I and II in FIG. 8. Zone I in FIG. 8 relates to a software-defined current limit associated with the switching current threshold (SCT), while Zone II relates to a software-defined overcurrent limit associated with the switching current threshold. In embodiments of the present invention, the SCT can be changed or set and controlled by software. This is indicated by the right R and left L arrows in FIG. 8. This means that when the measured current exceeds the current SCT, for example, the microcontroller software may decide to increase the SCT so that switching does not occur if the measured current is determined to be harmless to the circuit breaker itself or the load. Thus, this situation occurs when the measured current exceeds the current SCT but is below the circuit breaker's interrupting current. The opposite case, i.e., the SCT is reduced, can also occur. For example, to save costs (lower tariffs), the maximum rated current can be reduced by reducing the SCT. On the other hand, Zone III in FIG. 8 relates to a hardware-defined overcurrent limit, which is the same as the interrupting current.

[0080] As previously mentioned, embodiments of the present invention may relate to circuits with AC power, DC power, or both AC and DC power sources. In the following disclosure, the different AC and DC cases are explained in more detail with reference to the flow chart of FIG.

[0081] FIG. 9 shows a flow chart of the method according to the invention for the first switching device 106 .

[0082] 9, step I continuously measures or monitors the current supplied by power supply 302 to load 304. In an embodiment of the present invention, the current is monitored using current monitoring means 108 as previously described.

[0083] 9, it is checked whether the measured current is higher than the threshold current of the first switching device 106, i.e., the switching current of the first switching device 106. If NO at step II, i.e., the measured current is below the threshold current, the method returns to step I to continue measuring the current supplied by the power supply 302. However, if YES at step II, i.e., the measured current is higher than the threshold current, the method continues to step III.

[0084] In step III of Figure 9, it is checked whether the maximum number of consecutive overcurrent (e.g., inrush current) detections, n, has been reached, where n is a counter value indicating the number of consecutive overcurrent detections. If YES in step III, this is equivalent to the measured current being higher than the threshold current N times. If NO in step III, the method continues with step IV, or if YES in step III, the method continues with step V. In an embodiment of the invention, N is 10 or less. In a further embodiment of the invention, N is 6 or less.

[0085] 9, i.e., if step III returns NO, the first switching device 106 shuts off the circuit 300 by switching to the OFF mode for a first time interval T1, and then switches back to the ON mode. The counter n is incremented by a value of 1, i.e., n=n+1, and the method returns to step I.

[0086] In the AC case when the power supply 302 supplies AC to the load, according to an embodiment of the present invention, T1 is designed so that the first switching device 106 switches back to the ON mode at a zero crossing. Thus, the first time interval T1 depends on the zero crossing of the AC current. The first time interval T1 is, for example, the time interval between two consecutive zero crossings of the AC current, and thus the next zero crossing after an overcurrent is detected. Note that the first time interval T1 may vary between consecutive detected overcurrents. Thus, the first time interval T1 can be designed for optimal performance.

[0087] In the DC case when the power source supplies DC to the load 304, according to an embodiment of the present invention, the first time interval T1 depends on the energy storage characteristics of the current monitoring means 108. As mentioned above, the current monitoring means 108 may be an inductor, such as a coil, having a specific resistance configured to provide a value of the monitored current i supplied from the power source 302 to the load 304. Thus, in an embodiment, in the DC case, the first time interval T1 is longer than a threshold time interval that defines when the current monitoring means 108 has lost substantially all of its stored energy.

[0088] 9, i.e., if YES in step III, the first switching device 106 interrupts the circuit by switching to the OFF mode for a second time interval T2, where T2 is greater than T1, i.e., T2>T1. The counter n is also reset to zero, i.e., n=0, and the method returns to step I.

[0089] In the AC case, T2 is designed such that the first switching device 106 switches back to ON mode at the zero crossing after a consecutive number of zero crossings according to an embodiment of the present invention.

[0090] In an embodiment of the present invention, T2 is designed to be 5 seconds or less for both AC and DC due to human perception of electrical fault conditions. However, it should be noted that the parameter T2 can be designed to other values. Thus, in an embodiment, the parameter T2 can be dynamically adapted to various applications.

[0091] Finally, it must be understood that the present invention is not limited to the embodiments described above, but also relates to and incorporates all embodiments within the scope of the appended independent claims.

Claims

1. A residual current circuit breaker (RCCB) (100) for an electric circuit (300), configured to be coupled between a power source (302) and a load (304) of the electric circuit (300), comprising: a first switching device (106) and a second switching device (140) coupled in series with each other between the power source (302) and the load (304); The first switching device (106) is configured to detect when the value of the current i supplied to the load (304) exceeds the switching current threshold i of the first switching device (106). ｓ and when it is detected that the load voltage is greater than 0 V, the load (304) is switched to an OFF mode in which no current is supplied to the load (304); the second switching device (140) is configured to switch to an ON mode in which the load (304) is short-circuited when a leakage of the current i supplied to the load (304) is detected; The second switching device (140) comprises an electronic switch (142) coupled in parallel with a mechanical switch (144); the electronic switch (142) is configured to switch to an ON mode in which the load (304) is short-circuited when the leakage of the current i supplied to the load (304) is detected; The RCCB (100) is configured such that, when the mechanical switch (144) detects the leakage of the current i supplied to the load (304), it switches to an ON mode in which the load (304) is short-circuited.

2. The RCCB (100) of claim 1, wherein the second switching device (140) is coupled in parallel with the load (304).

3. The RCCB (100) of claim 1, wherein the electronic switch (142) is configured to switch back to an OFF mode in which the load (304) is not shorted after a period of time T.

4. 4. The RCCB (100) of claim 3, wherein the period T is greater than an ON switching time of the mechanical switch (144), the ON switching time being a period for the mechanical switch (144) to switch to the ON mode.

5. 5. The RCCB (100) of claim 1, wherein the mechanical switch (144) is configured to switch back to an OFF mode in which the load (304) is not shorted upon receiving a user (500) input.

6. The RCCB (100) The first current i of the first node (N1) of the electric circuit (300) １ Measure The second current i of the second node (N2) of the electric circuit (300) ２ Measure The first current i １ and the second current i2, and detects leakage of the current i supplied to the load (304). The RCCB (100) of any one of claims 1 to 5, comprising an earth leakage detector (150) configured to:

7. A residual current circuit breaker (RCCB) (100) for an electric circuit (300), configured to be coupled between a power source (302) and a load (304) of the electric circuit (300), comprising: a first switching device (106) and a second switching device (140) coupled in series with each other between the power source (302) and the load (304); The first switching device (106) is configured to detect when the value of the current i supplied to the load (304) exceeds the switching current threshold i of the first switching device (106). ｓ and when it is detected that the load voltage is greater than 0 V, the load (304) is switched to an OFF mode in which no current is supplied to the load (304); the second switching device (140) is configured to switch to an ON mode in which the load (304) is short-circuited when a leakage of the current i supplied to the load (304) is detected; The second switching device (140) comprises an electronic switch (142) coupled in parallel with a mechanical switch (144); The RCCB (100) The first current i of the first node (N1) of the electric circuit (300) １ Measure The second current i of the second node (N2) of the electric circuit (300) ２ Measure The first current i １ and the second current i2, and detects leakage of the current i supplied to the load (304). The earth leakage detector (150) is configured as follows: When detecting the leakage of the current i supplied to the load (304), the first current i １ and the second current i ２ RCCB(100) detects that the and have different values.

8. 8. The RCCB (100) of claim 6 or 7, wherein the first node (N1) is provided at a supply connector of the load (304) and the second node (N2) is provided at a return connector of the load (304).

9. The RCCB (100) of any one of claims 6 to 8, wherein the earth leakage detector (150) is configured to detect DC and / or AC leakage.

10. The RCCB (100) of claim 9, wherein the ground fault detector (150) is a Hall sensor.

11. The RCCB (100) according to any one of claims 1 to 10, comprising at least one control device (104; 104') configured to control at least one of the first switching device (106) and the second switching device (140).

12. A residual current circuit breaker (RCCB) (100) for an electric circuit (300), configured to be coupled between a power source (302) and a load (304) of the electric circuit (300), comprising: a first switching device (106) and a second switching device (140) coupled in series with each other between the power source (302) and the load (304); The first switching device (106) is configured to detect when the value of the current i supplied to the load (304) exceeds the switching current threshold i of the first switching device (106). ｓ and when it is detected that the load voltage is greater than 0 V, the load (304) is switched to an OFF mode in which no current is supplied to the load (304); the second switching device (140) is configured to switch to an ON mode in which the load (304) is short-circuited when a leakage of the current i supplied to the load (304) is detected; The second switching device (140) comprises an electronic switch (142) coupled in parallel with a mechanical switch (144); The first switching device (106) a) a first time interval T １ After that, the load (304) switches from the OFF mode back to the ON mode where the current i is supplied to the load (304). The RCCB (100) is configured as follows.

13. The first switching device (106) b) the value of the current i supplied to the load (304) is equal to or exceeds the switching current threshold i ｓ and when it detects that the voltage is greater than Repeat steps a) and b) N times, where N is a positive integer.

13. The RCCB (100) of claim 12, configured to:

14. The first switching device (106) When steps a) and b) have been repeated N times, the second time interval T ２ It remains in the OFF mode during 14. The RCCB (100) of claim 13, configured to:

15. The second time interval T ２ is the first time interval T １ The RCCB (100) of claim 14, wherein the RCCB (100) is greater than

16. A method (200) for an RCCB (100), the RCCB (100) being configured to be coupled between a power source (302) and a load (304) of a circuit (300), the RCCB (100) including a first switching device (106) and a second switching device (140) coupled in series with each other between the power source (302) and the load (304); The second switching device (140) comprises an electronic switch (142) coupled in parallel with a mechanical switch (144); the electronic switch (142) is configured to switch to an ON mode in which the load (304) is short-circuited when a leakage of the current i supplied to the load (304) is detected; the mechanical switch (144) is configured to switch to an ON mode in which the load (304) is short-circuited when the leakage of the current i supplied to the load (304) is detected; The method (200) comprises: The value of the current i supplied to the load (304) is the switching current i of the first switching device (106). ｓ switching (202) the first switching device (106) to an OFF mode in which no current is supplied to the load (304) when detecting that the load voltage is greater than and upon detecting the leakage of the current i supplied to the load (304), switching (204) the second switching device (140) to an ON mode in which the load (304) is short-circuited.

Images