CN113168980A

CN113168980A - Device for protecting an electric circuit, and electric circuit comprising such a device

Info

Publication number: CN113168980A
Application number: CN201980076699.0A
Authority: CN
Inventors: T·柴尔劳克斯; A·格劳得; J-F·欧弗拉德
Original assignee: Mersen France SB SAS
Current assignee: Mersen France SB SAS
Priority date: 2018-11-28
Filing date: 2019-11-27
Publication date: 2021-07-23
Also published as: WO2020109375A1; EP3888111A1; FR3089052A1; EP3888111B1; FR3089052B1

Abstract

An apparatus (2) for protecting a circuit (1) configured to transmit a current (I). In order to improve reliability, a protection device according to the present invention includes: a first conductor (4) and a second conductor (6); a first fuse (8) connected to the output conductor; at least one circuit breaker (12) for the current connected in parallel with the first fuse, the circuit breaker (12) comprising a control area (16) able to receive a trip signal (S) and a power supply area (18) for the passage of the current; a diagnostic system (30) comprises at least one sensor (32,34) for measuring the current flowing in a fuse (8) and an electronic processing unit (36,38) programmed to detect a fault of a protection device (2) according to the measured current value.

Description

Device for protecting an electric circuit, and electric circuit comprising such a device

Technical Field

The present invention relates to a protection device for an electrical circuit, and to an electrical circuit comprising such a protection device.

Background

In the field of protection of electric circuits, FR-3041143-B1 describes a hybrid protection device comprising a fuse and a pyrotechnic circuit breaker, also known as "pyroelectric switch" or "pyrotechnic switch", or even "pyroelectric switch", connected in parallel with each other. In the case of an electrical fault, an additional fuse connected in series with the power supply zone of the pyrotechnic circuit breaker generates a voltage when blown. This voltage is used as a signal to activate the pyrotechnic circuit breaker. Thus, the protection device may operate autonomously. Patent US2008137253, cited by FR-3041143-B1, describes a hybrid protection device comprising a fuse and a pyrotechnic circuit breaker connected in parallel to each other. However, in case of a fault there is a risk that the parallel fuse will not fulfil its function of assisting the opening of the circuit breaker, which may result in a complete loss of the required function.

These drawbacks are that the present invention more particularly aims to remedy by proposing a new protection device for electric circuits with improved reliability.

Disclosure of Invention

With this spirit in mind, the present invention relates to a protection device for a circuit configured to transmit current. According to the invention, the protection device comprises:

-a first conductor and a second conductor,

-a first fuse connected to the output conductor,

-at least one component for interrupting a current connected in parallel with said first fuse, said interrupting component comprising a control area capable of receiving a trip signal and a power supply area for the passage of current,

-a diagnostic system comprising at least one sensor for measuring the current flowing in said fuse and an electronic processing unit programmed to detect a fault of the protection device as a function of the measured current value.

By means of the invention, the diagnostic system makes it possible to detect, when necessary, a fault of a protection device that may prevent the tripping current of a pyrotechnic circuit breaker.

According to an advantageous but not compulsory aspect of the invention, such protection means comprise one or more of the following features, in any technically allowable combination:

-the protection device further comprises: a control circuit configured to generate and transmit a trip signal to a control zone of the circuit breaker; and a second fuse connected in series between the first conductor and the first fuse and capable of supplying a power supply voltage to a control circuit connected between the second fuse and a control region of the circuit breaker.

The diagnostic system comprises an additional sensor arranged to measure the current flowing in the circuit breaker supply area.

The diagnostic system comprises an additional sensor arranged to measure the current flowing through the second fuse.

The diagnostic system comprises an additional sensor arranged to measure the current flowing through the control zone of the circuit breaker.

The protection device comprises at least two circuit breakers, the respective power supply zones of which are connected in series with a second fuse between the first conductor and the second conductor, the diagnostic system comprising at least two sensors, each sensor being arranged to measure the current flowing through the control zone of one of the circuit breakers.

The protection device comprises at least two circuit breakers connected in parallel with the first fuse between the first conductor and the second conductor, the diagnostic system comprising at least two sensors, each sensor being arranged to measure the current flowing in the control zone of one of the circuit breakers.

The diagnostic system further comprises a temperature sensor and the electronic processing unit is programmed to correct the current measurement provided by the or each sensor according to the measured temperature.

The electronic processing unit of the diagnostic system is connected to the control circuit and is also programmed to generate a signal for tripping the circuit breaker when a fault of the protection device is detected.

The circuit breaker is a pyrotechnic circuit breaker.

The invention also relates to a circuit configured to be supplied with current, which circuit is equipped with a protection device according to the invention.

Drawings

The invention will be better understood and other advantages will become clearer from the following description of a protection device, a circuit and a method according to the invention, given purely by way of non-limiting example and with reference to the accompanying drawings. Wherein:

fig. 1 is a schematic diagram of a protection device and a circuit including the protection device according to the present invention.

Fig. 2 is a schematic view of the protection device of fig. 1 when the second fuse is blown.

Figure 3 is a schematic view similar to figure 2 when the pyrotechnic circuit breaker is open.

Fig. 4 is a schematic diagram similar to fig. 3 when the first fuse is blown.

Fig. 5 is a block diagram of a protection method according to the present invention. And

fig. 6 is a schematic diagram similar to fig. 1 for a protection device and circuit according to a second embodiment of the invention.

Detailed Description

In fig. 1, a circuit 1 is shown, the circuit 1 being configured to provide a current I and being equipped with a protection device 2. The circuit 1 comprises a load 3 and is intended to be connected to a source of direct or alternating current, not shown, depending on the load 3. The protection device 2 is able to open the electric circuit 1 when an electrical fault current flows through it. Electrical fault current is considered to have a value greater than or equal to nominal current value I_n(also called rated current I)_n) Any current I of intensity. The nominal current value I_nIs defined as the maximum current value to be flowed in the protection device 2 in normal operation. It is based on electricityThe properties of way 1 are predetermined. Thus, in the following description, the electrical fault current is defined as I_n+I_dIn which I_dIndicating an overload current. The maximum potential difference that can be applied between the terminals of the protection device 2 by supplying the load 3 without being tripped by the protection device 2 is called the nominal voltage value and is hereinafter denoted V_n. The nominal voltage value is also determined according to the nature of the circuit. Nominal current value I_nAnd a nominal voltage value V_nThe choice of (c) depends on the nature of the load 3 to be protected.

Electrical fault current I_dFor example an overload current or a short-circuit current, and constitutes a risk of the load 3 of the circuit 1. The protection device 2 comprises a first conductor 4 and a second conductor 6. In this example, the first conductor 4 forms an input conductor for electric current and the second conductor 6 forms an output conductor for electric current. A load 3 is connected to the output conductor. The

conductors

4 and 6 are configured to connect the protection device 2 to the rest of the circuit 1, thereby passing any current. In normal operation, i.e. in the absence of a fault current, the current I flowing between the

conductors

4 and 6 is less than or equal to the nominal current rating I_nAnd the voltage of the

conductors

4 and 6 is less than or equal to the nominal voltage rating V_n。

The protection device 2 further includes a first fuse 8 and a second fuse 10 electrically connected in series between the

conductors

4 and 6. The first fuse 8 is connected to the output conductor 6 and the second fuse 10 is connected in series between the input conductor 4 and the first fuse 8. Note that 5 is an intermediate conductor connecting the fuse 8 and the fuse 10 to each other, and thus it is interposed between the

conductors

4 and 6.

In a manner known per se, fuses are dipoles, the terminals of which are electrically connected to each other only by a conductive element which, when a current exceeding a threshold value flows through it, generally melts due to the joule effect and is thus destroyed. This threshold is referred to as the rated current. The rated voltage of the fuse is defined here as the value of the voltage at the fuse terminals above which the fuse cannot interrupt the current when the conductive element is broken. When the fuse has started to melt, if a voltage greater than this rated voltage is applied between its terminals, an arc is formed between these terminals and remains there, causing a current to flow.

In the following, the fuse is "melted" when the conductive element is broken and no arc can form given the value of the voltage in the circuit 1. It then forms an electrical open circuit, through which no current can flow. When the current flowing through the fuse exceeds the rated current, the fuse is "melted" causing the conductive element to begin to melt, but the voltage at its terminals to be higher than the rated voltage of the fuse, causing an arc to occur between its terminals. The arc continues as long as the fuse melts.

The first fuse 8 and the second fuse 10 have different ratings. In particular, the current rating I of the first fuse 8₈Significantly lower than the nominal value I_n. By "significant" is meant that the trip current is at least greater than the nominal value I_n4 times lower, e.g. ten or fifty times lower. Since the first fuse 8 is not normally used to carry the rated current I_nThis size is made possible. Tripping current I of second fuse 10₁₀Practically equal to the nominal value I_nWithin 1% or 3%. Thus, the tripping current I of the first fuse 8₈Significantly lower than the tripping current I of the second fuse 10₁₀。

Rated voltage V of first fuse 8₈Practically equal to the nominal value V_nWithin 1% or 3%. Rated voltage V of second fuse 10₁₀Significantly lower than the nominal value V_n. By "significant" is meant that the nominal voltage is at least greater than the nominal value V _n4 times lower, for example five or ten times lower. Therefore, the rated voltage V of the second fuse 10₁₀Significantly lower than the rated voltage V of the first fuse 8₈。

The protection device 2 further comprises a pyrotechnic circuit breaker 12 and a control circuit 14.

A pyrotechnic circuit breaker 12 is connected in parallel to the first fuse 8 between the intermediate conductor 5 and the output conductor 6. Pyrotechnic circuit breaker 12 includes a first zone 16 and a second zone 18.

The first zone 16 is referred to as the control zone and is adapted to receive a trip signal S. The second region 18 is referred to as a power region.

The power supply zone 18 is part of a pyrotechnic circuit breaker 12 electrically connected in parallel with the first fuse 8. It is configured for the passage of a current I supplied to the circuit 1. In particular, the power supply region 18 presents a resistance much lower than the resistance of the first fuse 8, for example at least ten times lower. Thus, when a current I flows through the protection device 2, it can be considered that such a current can be considered to flow through the second fuse 10 and the power zone 18 of the pyrotechnic circuit breaker 12, since only a negligible part of the current flows through the first fuse 8.

In practice, if it is greater than the rated current I_nFlows through the protection device 2, the second fuse 10 starts to melt and an arc a starts to appear between its terminals, as shown in fig. 2. The portion of the current flowing through the first fuse 8 is not strong enough to trigger melting of the first fuse 8. Thus, the second fuse 10 is sized and arranged to begin melting before the first fuse 8.

The control zone 16 of the pyrotechnic circuit breaker 12 includes a resistor 20, the resistor 20 being capable of heating when an electric current is passed through it. In a manner known per se, the pyrotechnic circuit breaker also comprises an explosive agent (e.g. an explosive powder) and a cut-off element (e.g. a piston or a guillotine) which are not shown. The cut-off element (not shown) is made of an electrically insulating material, such as plastic. It can switch off the power supply area 18. In effect, when current flows through the resistor 20 of the control region 16, the resistor 20 heats up and triggers the detonation of the explosive agent, which causes the severing element to move from its first position away from the power region 18 to its second position severing the power region 18, thereby interrupting the passage of current in the circuit 1.

The control circuit 14 is structured to generate and transmit a trip signal S to a control zone 16 of the pyrotechnic circuit breaker 12. The control circuit 14 is connected between the second fuse 10 and the control area 16. In practice, the trip signal S generated by the control circuit 14 is an electrical trip current I_sWhich is sent to the control area 16. Thus, the trip current I_sFlows through resistor 20 and trips pyrotechnic circuit breaker 12.

In a manner known per se, the control circuit 14 may comprise one or more active and/or passive electrical components for generating and sending the trip signal S. In particular, the control circuit 14 does not include an internal power supply.

According to a variant not shown in the figures, the control circuit 14 comprises a device able to control the tripping current I sent to the pyrotechnic circuit breaker 12_sThe potentiometer of (4). In practice, the potentiometer is configured to modulate the current I_sWhich is fed to the control zone 16 of the pyrotechnic circuit breaker 12. Thus, the potentiometer of the control circuit 14 is configured to control the opening speed of the pyrotechnic circuit breaker 12.

Thus, the protection device 2 is configured in different configurations C1, C2, C3 and C4, namely a closed configuration C1, a first intermediate configuration C2, a second intermediate configuration C3 and an open configuration C4.

In the closed configuration C1 shown in fig. 1, the current I supplied to the circuit 1 is smaller than the nominal current I_nAnd thus the first fuse 8 and the second fuse 10 are not blown.

In a first intermediate configuration C2 shown in fig. 2, the current I supplied to the circuit 1 is higher than a threshold value I_n. Then, the second fuse 10 starts to melt, and an arc a occurs between its terminals. The arc a causes the occurrence of a supply voltage V which is then supplied to the control circuit 14. In practice, the rated voltage V of the second fuse 10 is selected₁₀So that the arc a remains between its terminals when melted, as long as the current I flows.

In a second intermediate configuration C3 shown in fig. 3, the pyrotechnic circuit breaker 12 is tripped and the first fuse 8 is closed. The control circuit 14 supplied with the voltage V generates a trip signal S from the voltage V and with a current I_sIn a form that sends it to the resistor 20 of the control area 16 to trip the pyrotechnic circuit breaker 12, thereby quickly disconnecting the power supply area 18. Therefore, the current I flows through the first fuse 8.

In the open configuration C4 shown in fig. 4, the first fuse 8 and the second fuse 10 have melted. In fact, from the moment the second intermediate configuration C3 is reached, the electrical fault current causes the first fuse 8 to melt after a predetermined period of time (of the order of milliseconds (ms), depending on the characteristics of the first fuse 8). Due to the tripping current I of the first fuse 8₈Is selected to be significantly lower than the thresholdConstant current I_nSo that the first fuse 8 melts very rapidly when the current I flows through. Unlike the second fuse 10, the rated voltage V of the first fuse is₈Is equal to the nominal value V_nTherefore, the fuse rapidly melts and the arc at its terminals does not remain in the established state for a long time.

In fig. 1, control circuit 14 is shown as a "box" connected between second fuse 10 and control area 16. In fig. 2-4, the control circuit 14 is shown as a resistor 140 for reasons described below. The resistor 140 receives the power supply voltage V generated at the second fuse 10. Here, the value of the resistor 20 is less than ten times or one hundred times the value of the resistor 140. Thus, it is the value of resistor 140 that determines the current I sent to control zone 16_sThe value of (c). In fact, regardless of the electrical components of the control circuit 14, the control circuit 14 may be electrically represented in an electrical diagram by a simple resistor 140, as shown in fig. 2-4. In the schematic diagrams of fig. 2-4, resistor 140 is electrically connected in series with resistor 20. The assembly formed by the resistor 20 and the resistor 140 is electrically connected in parallel with the second fuse.

When a greater than nominal current I occurs in the circuit 1_nAnd flowing through the protection device 2, a method of protecting a circuit 1 having the protection device 2 is implemented. In this case, an overcurrent I_dStrictly greater than zero. By default, the protection device 2 is in the closed configuration C1 because the current I supplied to the circuit 1 and the first fuse 8 and the second fuse 10 do not melt. The protection method is as follows.

At the start of the method, in an initial step a) the power supply of the circuit 1 fails and a current flows through the protection device 2. As a result of this current, and within a time interval predetermined by the rating of the second fuse 10, the second fuse 10 begins to melt and an arc a forms on the second fuse 10. As mentioned above, the second fuse 10 is dimensioned such that when the second fuse 10 melts, the arc a remains present on the terminals as long as the current I is present, which generates the supply voltage V and ensures the current flow. This voltage V is used to power the control circuit 14. At the end of step a), the protection device2 is in its first intermediate configuration C2 in which the second fuse 10 is melting and the supply voltage V is provided to the control circuit 14. As described above, since the control circuit 14 is a passive circuit, the power supply voltage V supplied by the second fuse 10 represents the only power supply to the control circuit 14 required for the operation of the control circuit 14. Thus, in step a), the process comprises a step consisting of_nAnd the power supply of the control circuit (14) causes melting of the second fuse 10.

Then, the method comprises a step b) in which the control circuit 14 generates a trip current I_sCorresponding trip signal S. Subsequently, the control circuit 14 sends the trip current I_sTo the pyrotechnic circuit breaker 12 and in particular to the control zone 16 of the pyrotechnic circuit breaker 12. Since the arc a is still present across the second fuse 10, an electrical fault current I_dStill flows through the power zone 18 of the pyrotechnic circuit breaker 12. In step b), the method comprises sending a trip signal S to the pyrotechnic circuit breaker 12 with the help of the control circuit 14.

Subsequently, the method comprises a step c) comprising tripping the pyrotechnic circuit breaker 12 and opening the power supply zone 18 of the pyrotechnic circuit breaker 12. In practice, the current I_sFlowing through the resistor 20 of the control zone 16, it heats and triggers the detonation of the explosive agent of the pyrotechnic circuit breaker 12. As described above, the detonation of the explosive agent causes the circuit breaker element to flip from its first position to its second position, thereby interrupting the power supply area 18 of the pyrotechnic circuit breaker 12. At the end of step C), the protection device 2 is in its second intermediate configuration C3, in which the pyrotechnic circuit breaker 12 is tripped, the power supply zone 18 is opened, and the first fuse 8 is still closed.

Finally, the method comprises a step d) in which an electric current flows through the first fuse 8, since the power supply zone 18 of the pyrotechnic circuit breaker 12 is open. Since the first fuse 8 is undersized relative to the second fuse 10, the first fuse 8 is rapidly melted by the current I. Thus, the protection device 2 ensures that the circuit 1 is open, since no arc occurs in the area 18 of the circuit breaker 12. When the first fuse 8 melts, an arc may appear across the first fuse 8, but due to the nominal voltage of the first fuse 8 and the nominal voltage V_nWith the same numberStage, so the arc is extinguished very quickly. Once the first fuse 8 melts, the circuit opens and current I no longer flows. The arcs a are sequentially extinguished and the second fuse 10 is completely melted. The protection device 2 is then in its open configuration C4, in which the first fuse 8 and the second fuse 10 melt.

According to a second embodiment of the invention, the protection device 2 comprises two pyro-electric circuit breakers similar to the pyrotechnic circuit breakers 12. Two pyroelectric switches are connected in parallel to the first fuse 8 between the first conductor 4 and the second conductor 6. Specifically, each pyroelectric breaker includes a resistor 20. The resistors being connected in parallel, so that there is a proportion of the electrical tripping current I_sFlowing through them, which causes the resistors to heat up, as described above.

According to an embodiment not shown in the figures, the protection device 2 comprises three or more pyro-electric circuit breakers connected in parallel.

The introduction of a plurality of pyro-electric circuit breakers connected in parallel enables the protection device 2 to break the current I with a very high intensity. For example, according to a variant not shown, each pyro-electric circuit breaker is configured to break an electrical fault current I of 200 amperes_d. Thus, the protection device 2 is able to cut off the current I of total current 400 amperes.

Optionally, the load 3 is electrically connected to the first conductor 4. Then, in normal operation, current 1 flows from second conductor 6 to first conductor 4.

In all of these embodiments, the apparatus 2 further comprises a diagnostic system 30, the diagnostic system 30 comprising: at least one sensor, for example for measuring the current flowing through the pyrotechnic circuit breaker 12, in particular through the fuse 8; and an electronic processing unit programmed to detect a failure of the protection device from the measured current value. In these embodiments, the diagnostic system 30 includes a circuit for measuring the current I flowing in the control zone 16_sAnd a second sensor 34 for measuring the current I flowing in the power supply area 18. The electronic processing unit is programmed to compare the current values measured by the first sensor 32 and the second sensor 34 and to detect a fault of the protection device 2 on the basis of the measured current values.

In the embodiment of fig. 1-4, the system 30 includes a sensor 32 for measuring the current flowing through the fuse 8. Optionally, in the embodiment specifically illustrated in FIG. 3, the system 30 may additionally include a sensor 34 that measures the current flowing through the control zone 16.

It should be understood that the operation of the protection device 2 is independent of the positioning of the

sensors

32 and 34, as previously described with reference to fig. 1-5, and that the description thereof may be translated into other embodiments of different sensor arrangements of the diagnostic system 30.

Preferably, as shown in the embodiment shown in fig. 6, at least one sensor 34 of the diagnostic system 30 is arranged to measure the current in the fuse 8, for example by being connected in series with the fuse 8. The diagnostic system 30 may then include one or more additional sensors 32 that may be connected to the circuit breaker 12, for example, to the control area 16 and/or to the power area 18 and/or to the fuse 10 as shown in fig. 3 and 6.

The diagnostic system 30 is used to detect the occurrence of a fault that may affect the normal operation of the protection device 2, such as a failure of the control area 16, a failure of the fuse 10, a failure of the fuse 8 associated with the circuit breaker 12, or an accidental damage to one of the connectors.

In practice, according to an example, in the absence of a fault of the protection device 2, the current value I measured by the sensor 34_sIs correlated with the current value I measured by the other sensor. For example, the two current values I and I_sConnected by a proportional relationship as a function of the temperature of the protection device 2.

For example, if the current value I measured by the sensor 34_sA current value I measured by another sensor being zero is considered to be a fault in the protection device 2.

According to an exemplary embodiment, the diagnostic system includes a first electronic processing unit 36, the first electronic processing unit 36 being connected to a second remote electronic processing unit 38 via a data link 40.

The second processing unit 38 is configured to initiate measures for making the electric circuit 1 safe, for example, by disconnecting the power supply to the electric circuit 1 or by disconnecting the electric load 3, for example, by means of a not shown contactor or circuit breaker, for example, when a signal indicating a fault is received.

According to a first example, both the first sensor 32 and the second sensor 34 are connected to a first processing unit 36. The comparison and detection of the fault is performed by the first processing unit 36. The first processing unit 36 is further programmed to send a fault detection signal to the second processing unit 38 via a data link 40.

According to a second example, as shown in fig. 3, the first sensor 32 is connected to a first processing unit 36. The second sensor 34 is connected to a second processing unit 38. The comparison and detection of the fault is performed by the second processing unit 36. The first processing unit 36 is also programmed to send the current values measured by the current sensors to the second processing unit 38 via a data link 40.

These examples may be generalized to have

multiple sensors

32,34 other than two and/or variations where the

sensors

32,34 are arranged differently.

Preferably, sensors 32 and/or 34 are current sensors. For example, current sensors 32 and/or 34 are hall effect sensors or inductive sensors or current transformers.

Alternatively, sensors 32 and/or 34 comprise voltage sensors that measure the voltage across a resistor.

According to a further variant, the sensors 32 and/or 34 comprise current injection means comprising a coil surrounding the branch of the circuit in which the current to be measured flows, which means are able to inject a current (for example a pulse or a sinusoidal signal) exhibiting a predetermined shape into the branch by means of the coil. The device comprises a second coil surrounding said branch and allowing to measure the total current flowing in said branch, and a processing circuit allowing to automatically determine the value and/or the signal shape of the current to be measured flowing in said branch.

According to a variant not shown, the measurement of the current I by the system 30 is performed indirectly by measuring the electrical characteristics of the load 3. The respective sensor is therefore not associated with the electrical conductor of the circuit 1, but with the load 3. Then, the second sensor 34 is not necessarily a current sensor.

The

processing units

36 and 38 comprise, for example, dedicated electronic circuits and/or programmable microcontrollers.

The data link 40 is a wired link, such as a field bus, e.g. a CAN bus or a LIN bus, or even a wireless link.

According to a variant, the different components of the diagnostic system 30 can be integrated in the same housing in order to obtain compactness.

According to an example, at least some of the components of the diagnostic system 30 may be integrated in the same electronic component, for example an ASIC type integrated circuit.

According to a further embodiment, one example of which is shown in fig. 6, the previously described diagnostic system 30 is modified such that the second sensor 34 is arranged to measure the current flowing through the first fuse 8.

In this case, the electronic processing unit is still programmed to compare the current values measured by the first sensor 32 and the second sensor 34 and to detect a fault of the protection device 2 on the basis of the measured current values, but may be based on a calculation formula different from that described. Therefore, it is not necessary to measure the current flowing in the power supply region 18.

According to other variants, as mentioned above, additional sensors similar to the second sensor 34 may be arranged to measure the current flowing through the second fuse 10. This is to determine whether the second fuse 10 is still conducting and the circuit 14 is still able to be powered by the voltage V provided by the second fuse 10.

According to an alternative embodiment, the diagnostic system comprises a single sensor 32 or a single sensor 34 for measuring the current. For example, the sensor 32 or the sensor 34 is arranged to measure the current flowing in the control area 16, or preferably the current flowing through the fuse 8.

In this case, the

electronic processing unit

36,38 can be programmed to detect a fault of the protection device 2 only on the basis of the current values measured by the sensor 32 or the sensor 34.

In practice, measuring the current flowing through control area 16 verifies that control area 16 is still conductive and that no abnormal interruption has occurred, as such interruption would impair the tripping of circuit breaker 12. Similarly, measuring the current flowing through fuse 8 verifies that the fuse is still conductive.

According to a variant not shown, a diagnostic system similar to the diagnostic system 30 can be used in an embodiment of the protection device 2 comprising a plurality of circuit breaker components 12.

For example, one embodiment of the protection device 2 includes two pyroelectric circuit breakers 12A, 12B, whose respective power supply zones 18 are connected in series with the second fuse 10 between the first conductor 4 and the second conductor 6. The diagnostic system 30 then comprises at least two sensors, for example similar to the sensor 32, each of the two sensors being arranged to measure the current flowing in the control zone of one of the two pyrotechnic circuit breakers. In this case, the electronic processing unit is programmed to compare the current values measured by the two sensors in order to detect a fault of the protection device 2. This variant can be transposed to the case where the device 2 comprises more than two pyro-electric circuit breakers.

In another example, an alternative embodiment of the protection device 2 includes two pyro-electric circuit breakers 12A, 12B, whose respective power supply zones 18 are connected in parallel with the first fuse 8 between the first conductor 4 and the second conductor 6. The diagnostic system 30 then comprises at least two sensors, for example similar to the sensor 32, each of the two sensors being associated with one of the two pyrotechnic circuit breakers. For example, each of said sensors is arranged to measure the current flowing in the control zone of one of the two pyrotechnic circuit breakers.

According to other aspects, the diagnostic system 30 according to any of the embodiments described above may comprise a temperature sensor, preferably mounted near the device 2 or in contact with the device 2. In this case, the electronic processing unit is programmed to correct the current measurements provided by the or each sensor 32 and/or 34 according to the measured temperature.

The various embodiments described above can be generalized to circuit breakers 12 other than pyrotechnic breakers 12, such as power circuit breakers that are controllable by an actuation signal.

For example, alternatively, the pyrotechnic circuit breaker 12 may be replaced by an electronic circuit breaker 12, such as a circuit breaker or contactor. In this case, the power supply area 18 corresponds to a switching area having separable contacts, while the control area 16 corresponds to a trip mechanism that can be controlled by a voltage to open the contacts of the power supply area 18. According to other examples, the circuit breaker 12 includes a power transistor, and the control region 16 corresponds to a control electrode of the transistor, such as a gate of the transistor.

According to a modification, the second fuse 10 may be omitted. In this case, the control circuit 14 may be omitted. In this case, the trip signal S of the circuit breaker 12 is also generated by the external control circuit or diagnostic system 30.

The variants envisaged above may be combined with each other to produce new embodiments of the invention.

Claims

1. An apparatus (2) for protecting a circuit (1) configured to transmit a current (I), comprising:

-a first conductor (4) and a second conductor (6),

-a first fuse (8) connected to the second conductor (6),

at least one circuit breaker (12) for breaking the current connected in parallel with said first fuse, said circuit breaker (12) comprising a control zone (16) able to receive a trip signal and a power zone (18) for the passage of current,

-a diagnostic system (30), said diagnostic system (30) comprising at least one sensor (32,34) for measuring the current flowing in the fuse (8) and an electronic processing unit (36,38), said electronic processing unit (36,38) being programmed to detect a fault of the protection device (2) as a function of the measured current value.

2. The protection device (2) according to claim 1, wherein the protection device (2) further comprises:

-a control circuit (14) configured to generate and send said trip signal (S) to a control zone of said circuit breaker (12).

-a second fuse (10), said second fuse (10) being connected in series between said first conductor (4) and said first fuse (8) and being able to provide a supply voltage (V) to said control circuit (14) connected between said second fuse (10) and a control region (16) of said circuit breaker (12).

3. The protection device (2) according to claim 1 or 2, characterized in that the diagnostic system (30) comprises an additional sensor arranged to measure the current flowing in the power supply zone (18) of the circuit breaker (12).

4. Protection device according to claim 2, characterized in that said diagnostic system (30) comprises an additional sensor arranged to measure the current flowing through said second fuse (10).

5. Protection device according to any one of the preceding claims, characterized in that said diagnostic system (30) comprises an additional sensor (32), said additional sensor (32) being arranged to measure the current flowing through the control zone (16) of the circuit breaker (12).

6. The protection device (2) according to claim 2, characterized in that it comprises at least two circuit breakers (12) whose respective power supply zone (18) is connected in series with said second fuse (10) between said first conductor (4) and said second conductor (6), said diagnostic system (30) comprising at least two sensors, each sensor being arranged to measure the current flowing through the control zone of one of the circuit breakers.

7. The protection device (2) according to any one of the preceding claims, comprising at least two circuit breakers (12) connected in parallel with the first fuse (8) between the first conductor (4) and the second conductor (6), the diagnostic system (30) comprising at least two sensors, each sensor being arranged to measure the current flowing in the control zone of one of the circuit breakers.

8. The protection device (2) according to any one of the preceding claims, wherein the diagnostic system (30) further comprises a temperature sensor and the electronic processing unit (36,38) is programmed to correct the current provided by the or each sensor (32,34) according to the measured temperature.

9. The protection device (2) according to claim 2, characterized in that an electronic processing unit (36,38) of the diagnostic system (30) is connected to the control circuit (14) and is further programmed to generate a trip signal (S) of the circuit breaker (12) when a fault of the protection device (2) is detected.

10. Protection device (2) according to any one of the preceding claims, characterized in that said circuit breaker (12) is a pyrotechnic circuit breaker.

11. A circuit (1) configured to provide a current (I), the circuit being equipped with a protection device (2) according to any one of the preceding claims.