Overcurrent protection device, electric circuit assembly, and method for operating an electric circuit assembly

Abstract

The invention relates to an overcurrent protection device (10) comprising a first connection (12) for connecting to an electric energy source (14), a second connection (18) for connecting to a power converter (20), a melting element (22) which is arranged between the first and second connection (12, 18), a thermal conductor element (24), and a third connection (26) for connecting to the energy source (14), wherein the third connection (26) is electrically connected to the thermal conductor element (24). The invention additionally relates to an electric circuit assembly (36) and a method for operating an electric circuit assembly (36).

Description

[0001] Title : Overcurrent protection device, electrical

[0002] Circuit arrangement and a method for operating an electrical circuit arrangement

[0003] Description

[0004] The invention relates to an overcurrent protection device for protecting a power converter, an electrical circuit arrangement and a method for operating an electrical circuit arrangement.

[0005] In a circuit arrangement with a battery arrangement, a power converter can be provided. This can be used to charge or discharge the battery arrangement. The battery arrangement can in particular be a flow battery arrangement, also called a ‘flow battery arrangement’. Such a flow battery arrangement has special properties, as described further below. In the event of a short circuit within the power converter, a large overcurrent can flow, which can damage and possibly burn out the power converter and the peripheral electrical installation. It is therefore desirable to provide a fuse element as overcurrent protection, for example in the event of a short circuit.

[0006] DE 10 2009 017 518 A1 discloses an electrical circuit arrangement with such a fuse element.

[0007] Depending on the magnitude of the short-circuit current and the time it takes for a fuse element to blow, a short-circuit current may flow through a power converter, at least temporarily, and damage it.

[0008] The heat generated can cause a fire, which can result in major consequential damage.

[0009] WO2016 / 202844 A1, for example, describes a flow battery system with fault detection in the event of a short circuit in a DC / DC converter. However, this type of fault detection does not always work completely reliably. This document shows that several DC / DC converters, also called "converters", work in parallel for charging and / or discharging. These converters are often housed in a control cabinet and are all air-cooled, among other things, by fans. If a fire breaks out in just one of these converters, the spread of soot and smoke can damage all the converters before the short circuit is reliably detected. This can lead to very high levels of damage, which must be avoided at all costs.

[0010] It is therefore an object of the present invention to provide an overcurrent protection device for protecting a power converter, an electrical circuit arrangement and a method for operating an electrical circuit arrangement, wherein the above disadvantages are eliminated.

[0011] The above object is achieved by an overcurrent protection device for protecting a power converter having the features of claim 1. The overcurrent protection device can be a fuse. The overcurrent protection device can serve to protect an electrical circuit arrangement.

[0012] The overcurrent protection device comprises a first terminal for connection to an electrical energy source. The first terminal can be configured for connection to a first pole, in particular the positive pole, of the energy source.

[0013] The energy source can be a battery arrangement, in particular a flow battery arrangement. The overcurrent protection device is particularly suitable if the battery arrangement is a redox flow battery system. One such system is described by way of example in WO2016 / 202844 A1. WO2016 / 202844 A1 is hereby incorporated in its entirety into this application by reference.

[0014] The overcurrent protection device comprises a second terminal for connection to the power converter. The power converter can be configured as a bidirectional voltage converter. The power converter can be configured to charge and / or discharge the energy source. The power converter can be configured to connect the energy source and / or an electrical circuit arrangement to a supply network. The power converter can be configured like the battery inverter in WO2016 / 202844 A1.

[0015] The overcurrent protection device comprises a fusible element. The fusible element is arranged between the first and second terminals. The fusible element electrically connects the first and second terminals. The fusible element can heat up depending on the electrical current flowing through the fusible element. The fusible element can be designed with low resistance. The fusible element can have an electrical resistance of less than or equal to 0.1 ohms.

[0016] The overcurrent protection device comprises a thermal conductor element. The thermal conductor element can be a semiconductor element. The thermal conductor element is arranged at or on the fusible element so that heat can be transferred from the fusible element to the thermal conductor element. The thermal conductor element has an electrical connection to the first and / or second terminal, in particular via the fusible element. The thermal conductor element has a temperature-dependent conductivity for electrical current. The electrical resistance of the thermal conductor element decreases as the temperature of the thermal conductor element increases. In other words, the warmer or hotter the thermal conductor element is, the better or higher its conductivity for electrical current. This property can be realized particularly well with a semiconductor. In addition, semiconductors are widely used and well-tested in electronics in various designs.

[0017] The overcurrent protection device comprises a third terminal for connection to the energy source. The third terminal can be designed for connection to a second pole, in particular the negative pole, of the energy source. The third terminal is electrically connected to the thermal conductor element. The third terminal can be arranged on or at the thermal conductor element. The third terminal can be arranged on or at the thermal conductor element, in particular in such a way that the thermal conductor element is electrically connected between the fusible element and the third terminal and can thus influence the current flow between the third terminal and optionally the first and / or second terminal.

[0018] As soon as an increased electric current flows through the melting element, for example due to a short circuit in the power converter, the melting element heats up. The heating of the melting element leads to heating of the thermally induced conductivity ...

[0019] In this way, in the event of a short circuit in the power converter, the electrical energy or the electrical current (short-circuit current or overcurrent) can be diverted via the third connection of the overcurrent protection device (in particular back to the energy source). The power converter can thus be bridged, so to speak. This keeps the short-circuit current or overcurrent away from the power converter and prevents corresponding damage to the power converter. According to a development of the overcurrent protection device, the overcurrent protection device is designed such that in a first state the thermal conductor element is electrically insulating. This allows the electrical current to flow from the first connection via the fusible element to the second connection. This means that no electrical current can flow between the first connection and the third connection. In the first state, the thermal conductor element can have a temperature of less than or equal to 70 °C (Celsius).

[0020] In the first state, the overcurrent protection device does not divert the electrical current. This ensures proper operation of the electrical energy source and / or power converter.

[0021] According to a further development, the overcurrent protection device can be configured such that, in a second state, the thermal conductor element is electrically conductive. Thus, the electrical current can flow from the first terminal, at least partially, to the third terminal via the thermal conductor element. In particular, the electrical current can flow from the first terminal, at least partially, to the third terminal via the thermal conductor element and also at least partially, via the fusible element. In the second state, the thermal conductor element can have a temperature greater than 70°C.

[0022] In the second state, the overcurrent protection device diverts the electrical current. In particular, the overcurrent protection device triggers in the second state. This can prevent a short-circuit current or overcurrent from flowing through the power converter in the event of a short circuit in the power converter. What is interesting and unexpected about this overcurrent protection device is the effect that the overcurrent is not interrupted, but simply diverted to another path. This keeps the overcurrent away from the power converter. The overcurrent protection device can be arranged in such a way that no destructive fire occurs in the control cabinet of the power converter(s). Of course, the fusible element can still burn through as a result, leading to an interruption in the current flow.But the primary goal here is to keep the destructively high current away from the power converter(s).

[0023] According to a further development, the overcurrent protection device can be configured such that the overcurrent protection device is in the first state when an electrical current that is less than a predetermined overcurrent value flows through the overcurrent protection device. In particular, the overcurrent protection device can be in the first state when an electrical current that is less than a predetermined overcurrent value flows through the first and second terminals and / or the fusible element.

[0024] The overcurrent value can be selected so that it corresponds to an overcurrent or a short-circuit current. The overcurrent protection device can be set to a predetermined overcurrent value. The thermally conductive element and / or the fusible element can be configured such that the thermally conductive element is electrically insulating when an electrical current flowing through the overcurrent protection device is less than the predetermined overcurrent value. In this way, the proper operation of the energy source and / or the power converter can be guaranteed as long as the electrical current does not exceed the predetermined overcurrent value, i.e. as long as there is no fault, e.g. a short circuit in the power converter.

[0025] According to a further development, the overcurrent protection device can be in the second state if an electrical current greater than the predetermined overcurrent value flows through the overcurrent protection device. In particular, the overcurrent protection device can be in the second state if an electrical current greater than the predetermined overcurrent value flows through the first terminal and / or at least partially through the fusible element.

[0026] The overcurrent value can be selected to correspond to an overcurrent or a short-circuit current. The overcurrent protection device can be set to a predetermined overcurrent value. The thermally conductive element and / or the melting element can be configured such that the thermally conductive element is electrically conductive when the electrical current flowing through the overcurrent protection device is greater than the predetermined overcurrent value.

[0027] This ensures that in the event of an overcurrent or short-circuit current, the electrical current is diverted by the overcurrent protection device and does not enter the power converter. According to a further development, the overcurrent protection device can have a housing. The melting element and the thermal conductor element can be arranged at least partially, in particular entirely, within the housing.

[0028] This allows for optimized handling of the overcurrent protection device. Furthermore, the housing can prevent or at least minimize potential sparks emanating from the fuse element and / or the thermal element (particularly in the event of a short circuit or if the overcurrent protection device is triggered).

[0029] According to a further development, the overcurrent protection device can have a measuring terminal for connecting a voltage measuring device. The measuring terminal can be electrically connected to the third terminal. The voltage measuring device can be an electrical voltmeter or an electrical voltmeter.

[0030] This makes it possible to monitor with simple means whether an electrical current is flowing through the third connection and thus whether the overcurrent protection device is triggered or not.

[0031] According to a further development, the melting element and / or the thermal conductor element can be arranged and designed in such a way that the electrical current flowing through the third terminal in the second state leads to a burning through, also called 'melting', of the melting element and thus to an interruption of current both between the first and the second terminal and between the first and the third

[0032] connection. Such a design of the thermal conductor element can be implemented, for example, by adjusting the thermally induced electrical conductivity. This can be adjusted, for example, in the case of a thermal conductor element designed as a semiconductor element by varying a doping. Such a design of the fusible element can be implemented, for example, by adjusting the electrical resistance of the fusible element. This can be adjusted, for example, by choosing the material from which the fusible element is made, e.g. low-resistance or high-resistance material. Furthermore, the size, shape and / or dimensioning of the thermal conductor element, the fusible element and / or a contact surface between the thermal conductor element and the fusible element can be varied in order to design the thermal conductor element and / or the fusible element as required.

[0033] This allows for a simple physical separation of the electrical connection between the energy source and the power converter. Furthermore, a simple physical separation of the electrical connection between the first, second, and third terminals can be achieved. This further reduces the risk of damage to the energy source and / or the power converter.

[0034] The above object is further achieved by an electrical circuit arrangement having the features of claim 9.

[0035] The electrical circuit arrangement comprises at least one energy source. The energy source can be a battery arrangement, in particular a flow battery arrangement. The overcurrent protection device is particularly suitable if the battery arrangement is a redox flow battery system, as described by way of example in WO2016 / 202844 A1.

[0036] The electrical circuit arrangement comprises at least one power converter. The power converter can be designed as a bidirectional voltage converter. The power converter can be configured to charge and / or discharge the energy source. The power converter can be configured to connect the energy source and / or an electrical circuit arrangement to a (power) supply network. The power converter can, in particular, be designed like the battery inverter in WO2016 / 202844 A1.

[0037] The electrical circuit arrangement comprises at least one overcurrent protection device according to the above embodiments. The first terminal of the overcurrent protection device is electrically connected to the energy source. The first terminal of the overcurrent protection device can be electrically connected to a first pole, in particular the positive pole, of the energy source. The second terminal of the overcurrent protection device is electrically connected to the power converter. The third terminal of the overcurrent protection device is electrically connected to the energy source. The third terminal of the overcurrent protection device can be electrically connected to a second pole, in particular the negative pole, of the energy source.

[0038] With regard to the advantages achievable with the electrical circuit arrangement, reference is made to the relevant explanations regarding the overcurrent protection device. The measures described in connection with the overcurrent protection device and / or those explained below can be used to further refine the electrical circuit arrangement.

[0039] According to a further development, the electrical circuit arrangement can have a voltage measuring device for measuring an electrical voltage between the first terminal and the third terminal. The voltage measuring device can be configured to measure an electrical voltage between the first terminal and the measuring terminal.

[0040] This makes it easy to monitor whether an electrical current is flowing through the third terminal and thus whether the overcurrent protection device is triggered or not.

[0041] The above object is further achieved by a method for operating an electrical circuit arrangement having the features of claim 11.

[0042] The procedure includes the following steps:

[0043] - Providing the electrical circuit arrangement with at least one energy source, at least one power converter, and at least one overcurrent protection device. The overcurrent protection device is arranged between the energy source and the power converter.

[0044] - Operating the electrical circuit arrangement in a first state of the overcurrent protection device. In the first state of the overcurrent protection device, an electrical current flows from the energy source to the power converter via the overcurrent protection device. The electrical current flowing through the overcurrent protection device is less than a predetermined overcurrent value.

[0045] - Changing the current flow of the electrical circuit arrangement in a second state of the overcurrent protection device. In the second state of the overcurrent protection device, an electrical current flows from the energy source back to the energy source via the overcurrent protection device. The electrical current flowing through the overcurrent protection device is greater than the predetermined overcurrent value.

[0046] This allows the electrical energy or current (short-circuit current or overcurrent greater than the overcurrent limit) to be diverted via the overcurrent protection device (back to the power source) in the event of a short circuit in the power converter. This effectively bypasses the power converter. This keeps the short-circuit current or overcurrent away from the power converter, preventing damage to the power converter.

[0047] According to a further development, the procedure may include the step :

[0048] - Measuring an electrical voltage applied to the overcurrent protection device. The applied electrical voltage can be measured at a measuring terminal of the overcurrent protection device, preferably using a voltage measuring device. If the magnitude of the measured electrical voltage decreases, it can be concluded that an overcurrent or a short circuit, e.g., in the power converter, is present and / or that the overcurrent protection device has been triggered.

[0049] This allows monitoring of the overcurrent protection device to be implemented using simple means.

[0050] According to a further development, the procedure may include the step :

[0051] - Implementation of at least one protective measure when a reduction in the magnitude of the measured electrical voltage, also called "voltage drop," is detected across the overcurrent protective device. In particular, a protective measure can be implemented when tripping of the overcurrent protective device is detected (by measuring the electrical voltage applied to the overcurrent protective device).

[0052] This makes it possible to link the execution of protective measures with the status (or triggering) of the overcurrent protection device using simple means.

[0053] According to a development of the method, a protective measure can be the output of an acoustic and / or optical alarm signal. This can alert the environment, for example an operator and / or maintenance person, to the triggering of the overcurrent protection device and the associated fault (e.g. short circuit). A protective measure can be the stopping of a pumping process of at least one energy source designed as a flow battery arrangement. This can stop or at least reduce the supply of energy by means of the energy source. The energy source can thus be switched off.

[0054] One protective measure could be to shut down at least one power converter. This could involve, for example, physically disconnecting an electrical connection to the power converter. This can further reduce the risk of damage to the power converter.

[0055] According to a further development of the method, an electrical circuit arrangement according to the above statements can be operated by means of the method.

[0056] With regard to the advantages achievable with the method, reference is made to the relevant explanations regarding the electrical circuit arrangement. The measures described in connection with the electrical circuit arrangement and / or those explained below may serve to further refine the method.

[0057] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show:

[0058] Fig. 1 is a schematic representation of an overcurrent protection device; Fig. 2 is a schematic representation of an electrical circuit arrangement with the overcurrent protection device according to Figure 1 in a first state and

[0059] Fig. 3 is a schematic representation of the electrical circuit arrangement according to Figure 2 with the overcurrent protection device according to Figure 1 in a second state.

[0060] In the following description and in the figures, corresponding components and elements bear the same reference symbols. For the sake of clarity, not all reference symbols are shown in all figures.

[0061] Figure 1 shows a schematic representation of an overcurrent protection device 10. The overcurrent protection device 10 is embodied as a fuse. The overcurrent protection device 10 is designed to protect a power converter 20 (see Figures 2 and 3).

[0062] The overcurrent protection device 10 includes a first terminal 12 for connection to an electrical energy source 14, as shown in Figures 2 and 3. The overcurrent protection device 10 includes a second terminal 18 for connection to the power converter 20, as shown in Figures 2 and 3.

[0063] The overcurrent protection device 10 comprises a melting element 22. The melting element 22 is arranged between the first and second terminals 12, 18. The melting element 22 electrically connects the first and second terminals 12, 18 to one another. The melting element 22 can heat up depending on the electrical current flowing through the melting element 22. In this case, the melting element 22 is designed to be low-ohm, i.e., to have a low electrical resistance, e.g., less than or equal to 0.1 Ω.

[0064] The overcurrent protection device 10 comprises a thermal conductor element 24. The thermal conductor element 24 is embodied as a semiconductor element. The thermal conductor element 24 is arranged on the melting element 22. In other words, the thermal conductor element 24 and the melting element 22 have a common contact surface. This allows heat to be transferred from the melting element 22 to the thermal conductor element 24.

[0065] In this case, the thermal conductor element 24 has an electrical connection to the first and second terminals 12, 18 via the melting element 22. In other words, the melting element 22 represents an electrical connection between the first terminal 12, the second terminal 18, and the thermal conductor element 24.

[0066] The thermal conductor element 24, which is designed as a semiconductor element in the present case, has a temperature-dependent conductivity for electrical current. The temperature-dependent conductivity can be adjusted as desired, for example, by doping the thermal conductor element 24, which is designed as a semiconductor element. The electrical resistance of the thermal conductor element 24 decreases with increasing temperature of the thermal conductor element 24. The overcurrent protection device 10 comprises a third

[0067] Terminal 26 for connection to the energy source 14, as shown, for example, in Figures 2 and 3. The third terminal 26 is electrically connected to the thermal conductor element 24. The third terminal 26 is arranged on the thermal conductor element 24.

[0068] The overcurrent protection device 10 is configured such that, in a first state, the thermal conductor element 24 is electrically insulating. This allows the electrical current to flow from the first terminal 12 via the fusible element 22 to the second terminal 18. No electrical current can flow between the first terminal 12 and the third terminal 26. In the first state, the thermal conductor element 24 has a temperature of less than or equal to 40°C.

[0069] The overcurrent protection device 10 is in the first state when an electrical current which is less than a predetermined overcurrent value flows through the overcurrent protection device 10, in this case via the first and second terminals 12, 18 and the melting element 22.

[0070] The overcurrent protection device 10 is configured in such a way that in a second state the thermal conductor element 24 is electrically conductive. This allows the electrical current to flow from the first terminal 12 via the fusible element 22 and the thermal conductor element 24 to the third terminal 26. In the second state, the thermal conductor element 24 has a temperature of greater than 70°C. The overcurrent protection device 10 is in the second state when an electrical current which is greater than the predetermined overcurrent value flows via the overcurrent protection device 10, in this case via the first terminal 12, at least partially via the fusible element 22, via the thermal conductor element 24 and the third terminal 26.

[0071] The melting element 22 and the thermal conductor element 24 are arranged and designed in such a way that the electrical current flowing through the third terminal 26 in the second state leads to a burning through, also called 'melting through,' of the melting element 22. This leads to a (physical) current interruption both between the first and second terminals 12, 18 and to a (physical) current interruption between the first and third terminals 12, 26.

[0072] The overcurrent protection device 10 comprises a housing 30. The melting element 22 and the thermal conductor element 24 are arranged entirely within the housing 30.

[0073] In this case, the overcurrent protection device 10 has a measuring terminal 32 for connecting a voltage measuring device 34. The measuring terminal 32 is electrically connected to the third terminal 26. The measuring terminal 32 is arranged at or on the third terminal 26.

[0074] Figure 2 shows a schematic representation of an electrical circuit arrangement 36 with the overcurrent protection device 10 according to Figure 1 in the first state. The electrical circuit arrangement 36 comprises an energy source 14. The energy source 14 is embodied as a flow battery arrangement. The electrical circuit arrangement 36 comprises a power converter 20, which is embodied as a bidirectional voltage converter.

[0075] The overcurrent protection device 10 is arranged between the energy source 14 and the power converter 20. The first terminal 12 of the overcurrent protection device 10 is electrically connected to a first pole 16 of the energy source 14. The first pole 16 can be the positive pole. The second terminal 18 of the overcurrent protection device 10 is electrically connected to the power converter 20. The third terminal 26 of the overcurrent protection device 10 is electrically connected to a second pole 28 of the energy source 14. The second pole 28 can be the negative pole.

[0076] The electrical circuit arrangement 36 in the present case comprises a voltage measuring device 34 for measuring an electrical voltage between the first terminal 12 and the measuring terminal 32 and / or the third terminal 26.

[0077] A method for operating the electrical circuit arrangement 36 is described below:

[0078] After the electrical circuit arrangement 36 has been provided, the electrical circuit arrangement 36 is operated in the first state of the overcurrent protection device 10. In the first state of the overcurrent protection device 10, an electrical current flows from the energy source 14 via the overcurrent protection device 10 to the power converter 20. This is indicated in Figure 2 by a dashed arrow. The electrical current flowing via the overcurrent protection device 10 is less than a predetermined overcurrent value. The first state therefore represents the proper operation of the electrical circuit arrangement 36.

[0079] Figure 3 shows a schematic representation of the electrical circuit arrangement 36 according to Figure 2 with the overcurrent protection device 10 according to Figure 1 in a second state.

[0080] If, for example, a short circuit occurs in the power converter 20, the electrical circuit arrangement 36 can be operated in the second state. In the second state of the overcurrent protection device 10, an electrical current flows from the energy source 14 via the overcurrent protection device 10 and back to the energy source 14 via the third connection 26. This is indicated in Figure 3 by means of a dashed arrow. The electrical current flowing via the overcurrent protection device 10 is greater than a predetermined overcurrent value. The second state therefore represents the fault case, in particular a short circuit in the power converter 20, in which the overcurrent protection device 10 triggers in order to protect the power converter 20 from overcurrent (or short-circuit current).

[0081] In the second state, the electrical current flowing from the energy source 14 via the overcurrent protection device 10 is diverted so that it does not reach the power converter 20 and thus corresponding damage in the power converter 20 due to the overcurrent can be avoided or at least reduced.

[0082] During operation of the electrical circuit arrangement 36, the applied electrical voltage is measured at the overcurrent protection device 10 by means of the voltage measuring device 34. Since, in the second state of the overcurrent protection device 10, the electrical current flows from the first terminal 12 to the third terminal 26 by means of the thermally conductive element 24, a reduction in the magnitude of the measured electrical voltage can be measured in the second state by means of the voltage measuring device 34.

[0083] Thus, the state of the overcurrent protection device 10 can be monitored via the voltage measurement by means of the voltage measuring device 34. If a reduction in the measured electrical voltage or its magnitude is detected, at least one protective measure can be implemented.

[0084] A protective measure can, for example, be the output of an acoustic and / or visual alarm signal to alert the surrounding area, in particular the operating personnel. A protective measure can also be stopping a pumping process of the energy source 14, which is designed as a flow battery arrangement, in order to switch off the energy source 14. A further protective measure can be switching off the power converter 20, wherein the power converter 20 can be physically separated from the energy source 14 and / or from the electrical circuit arrangement 36.

Claims

Patent claims 1. Overcurrent protection device (10), in particular a fuse, for protecting a power converter (20), comprising: a first terminal (12) for connection to an electrical energy source (14), in particular to a first pole (16), preferably the positive pole, of the energy source (14), wherein the energy source (14) is preferably a battery arrangement, particularly preferably a flow battery arrangement, a second terminal (18) for connection to the power converter (20), a fusible element (22) arranged between the first and the second terminal (12, 18) and electrically connecting them to one another, wherein the fusible element (22) heats up or can heat up depending on the electrical current flowing through the fusible element (22), a thermal conductor element (24), in particular a semiconductor element, wherein the thermal conductor element (24) is arranged on or on the fusible element (22),so that heat can be transferred from the melting element (22) to the thermal conductor element (24), wherein the thermal conductor element (24) has an electrical connection to the first and / or to the second terminal (12, 18), in particular via the melting element (22), wherein the thermal conductor element (24) has a temperature-dependent conductivity for electrical current, wherein the electrical resistance of the thermal conductor element (24) increases with increasing temperature of the, Heat conductor element (24), a third terminal (26) for connection to the energy source (14), in particular to a second pole (28), preferably negative pole, of the energy source (14), wherein the third terminal (26) is electrically connected to the heat conductor element (24).

2. Overcurrent protection device (10) according to claim 1, characterized in that the overcurrent protection device (10) is set up such that in a first state, in particular in which the thermal conductor element (24) has a temperature of less than or equal to 40° C, the thermal conductor element (24) is electrically insulating, so that the electrical current can flow from the first terminal (12) via the fusible element (22) to the second terminal (18) and no electrical current can flow between the first terminal (12) and the third terminal (26).

3. Overcurrent protection device (10) according to claim 1 or 2, characterized in that the overcurrent protection device (10) is designed such that in a second state, in particular in which the thermal conductor element (24) has a temperature of more than 40° C, in particular heated by the melting element (22), the thermal conductor element (24) is electrically conductive, so that the electrical current can flow from the first terminal (12) at least partially via the thermal conductor element (24) to the third terminal (26).

4. Overcurrent protection device (10) according to claim 2 or 3, characterized in that the Overcurrent protection device (10) is configured such that the overcurrent protection device (10) is in the first state when an electrical current which is less than a predetermined overcurrent value flows via the overcurrent protection device (10), in particular the first and second terminals (12, 18) and / or the fusible element (22).

5. Overcurrent protection device (10) according to claim 3 or 4, characterized in that the overcurrent protection device (10) is in the second state when an electric current which is greater than the predetermined overcurrent value flows via the overcurrent protection device (10), in particular the first terminal (12) and / or at least partially the fusible element (22).

6. Overcurrent protection device (10) according to one of the preceding claims, characterized in that the overcurrent protection device (10) has a housing (30), wherein the fusible element (22) and the thermal conductor element (24) are arranged at least partially, in particular completely, within the housing (30).

7. Overcurrent protection device (10) according to one of the preceding claims, characterized in that the overcurrent protection device (10) has a measuring connection (32) for connecting a voltage measuring device (34), wherein the measuring connection (32) is electrically conductively connected to the third connection (26).

8. Overcurrent protection device (10) according to one of the preceding claims, characterized in that the fusible element (22) and / or the thermal conductor element (24) are arranged and designed such that the electrical current flowing through the third terminal (26) in the second state leads to a burning through of the fusible element (22) and thus to an interruption of current both between the first and second terminals (12, 18) and between the first and third terminals (12, 26).

9. Electrical circuit arrangement (36) comprising at least one energy source (14), in particular a battery arrangement, preferably a flow battery arrangement, at least one power converter (20), in particular a bidirectional voltage converter, at least one overcurrent protection device (10) according to one of the preceding claims, wherein the first connection (12) of the overcurrent protection device (10) is electrically connected to the energy source (14), in particular to a first pole (16), preferably the positive pole, of the energy source (14), wherein the second connection (18) of the overcurrent protection device (10) is electrically connected to the power converter (20) and wherein the third connection (26) of the overcurrent protection device (10) is electrically connected to the energy source (14), in particular to a second pole (28), preferably the negative pole, of the energy source (14).

10. Electrical circuit arrangement (36) according to claim 9, characterized in that the electrical Circuit arrangement (36) has a voltage measuring device (34) for measuring an electrical voltage between the first terminal (12) and the third terminal (26), in particular between the first terminal (12) and the measuring terminal (32).

11. A method for operating an electrical circuit arrangement (36) comprising the steps of: providing the electrical circuit arrangement (36) with at least one energy source (14), at least one power converter (20) and at least one overcurrent protection device (10), wherein the overcurrent protection device (10) is arranged between the energy source (14) and the power converter (20), Operating the electrical circuit arrangement (36) in a first state of the overcurrent protection device (10), in which an electrical current flows from the energy source (14) via the overcurrent protection device (10) to the power converter (20), wherein the electrical current flowing via the overcurrent protection device (10) is less than a predetermined overcurrent value, Changing the current flow of the electrical circuit arrangement (36) in a second state of the overcurrent protection device (10), in which an electrical current flows from the energy source (14) via the overcurrent protection device (10) back to the energy source (14), wherein the electrical current flowing via the overcurrent protection device (10) is greater than the predetermined overcurrent value.

12. The method according to claim 11, characterized in that the method comprises the step: Measuring an electrical voltage applied to the overcurrent protection device (10), in particular at a measuring terminal (32) of the overcurrent protection device (10), preferably by means of a voltage measuring device (34).

13. The method according to claim 12, characterized in that the method comprises the step: Carrying out at least one protective measure when a reduction in the magnitude of the measured electrical voltage is measured at the overcurrent protection device (10).

14. The method according to claim 13, characterized in that a protective measure can be an output of an acoustic and / or optical alarm signal, a stopping of a pumping process of at least one energy source (14) designed as a flow battery arrangement and / or a switching off of at least one power converter (20).

15. Method according to one of claims 11 to 14, characterized in that an electrical circuit arrangement (36) according to one of claims 9 or 10 is operated by means of the method.

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