Circuit breaker with electronic trip control

Abstract

The invention relates to a circuit breaker with electronic tripping control. The circuit breaker is crossed by at least one current path (L1, L2, L3) and is able to be protected against at least one short-circuit type fault occurring in a circuit connected to the current path (L1, L2, L3); the circuit breaker comprises: a power supply (A); a current detector (D) able to detect the current in the current path (L1, L2, L3) or in at least one of the current paths (L1, L2, L3); an electronic tripper (3, I2, 4, 5) comprising an electronic processing unit (3); an actuator (1) comprising a coil (10); and a disconnection mechanism able to be actuated by the actuator (1); the circuit breaker further comprises a suppression circuit (2, 2', I1) for suppressing the magnetic influence on the actuator that can cause an accidental trip, able to short-circuit the coil; the electronic processing unit is further configured to be able to control the suppression circuit and to coordinate the emission of a tripping control signal with the control of the suppression circuit so as not to short-circuit the coil at the same time as the trip occurs.

Description

Technical Field

[0001] This invention relates to the field of protecting circuits from faults (e.g., short circuits), and to circuit breakers with electronic trip control. Background Technology

[0002] The function of a protective device (such as a circuit breaker) is to interrupt the current in the event of a fault in the circuit.

[0003] In equipment comprising multiple protection devices, selectivity lies in coordinating these devices so that when a fault occurs in the circuit to be protected, only the protection device closest to the fault trips, thereby preventing the other electrical equipment from becoming unusable. This improved method of coordinating protection devices ensures service continuity.

[0004] Several selective techniques are known, specifically current-based selective and time-based selective. Current-based selective is based on the tripping thresholds of the upstream and downstream circuit breakers, while time-based selective involves delaying the tripping of the upstream circuit breaker so that the downstream circuit breaker trips first when the tripping threshold is exceeded.

[0005] If the selectivity is ensured to reach the assumed maximum value of the short-circuit current at the downstream circuit breaker location, the selectivity between the upstream and downstream circuit breakers is referred to as the total selectivity. The selectivity limit is defined as an indication of a short-circuit current value below which only the downstream circuit breaker will trip.

[0006] In selective electrical protection devices, circuit breakers with electronic trip control ensure protection against at least one type of fault, such as a short circuit occurring in the circuit. When a fault occurs, these circuit breakers are able to trip by opening at least one main contact, thereby interrupting the current in at least one current path that passes through the circuit breaker and is functionally connected to the circuit. Such circuit breakers typically include:

[0007] A current detector is provided for detecting current in the current path or at least one of the current paths. For this purpose, the current detector includes: a current sensor, wherein one current sensor is provided for each current path; and a regulating circuit that emits an acquisition signal indicating the current flowing in the current path.

[0008] An electronic trip unit, comprising an analog electronic processing unit or a microprocessor-based electronic processing unit, the electronic processing unit being configured to process the acquisition signal emitted by the detector and to simultaneously or with a delay issue a trip control signal when a trip threshold has been exceeded;

[0009] An actuator, driven by the trip control signal, includes a coil, which is an electromagnet-type coil, surrounding a movable iron core, typically an iron core, a compression spring, and a permanent magnet. When the actuator is not tripping, the iron core is attracted by the permanent magnet in the coil. When a trip occurs, the coil is supplied with current and generates a magnetic field opposite to and exceeding that of the permanent magnet, which has the effect of axially moving the iron core with the assistance of the spring's thrust, and subsequently actuating the disconnecting mechanism; and

[0010] The disconnecting mechanism, also known as the locking mechanism, is capable of actuating the disconnection of the main contacts under the movement of the impactor; and

[0011] A power supply, which may or may not be integrated into the electronic trip unit, is used to provide energy, i.e., current and voltage, to the coils of the electronic processing unit and the actuator.

[0012] The supply of current to the electronic processing unit is typically ensured through at least one current path and a power supply device, such as a current transformer functionally connected to the current path.

[0013] The circuit breaker also includes a transistor (MOSFET) type controlled switch, which is typically activated by a trip control signal from an electronic processing unit. When controlled to be closed, the controlled switch can close a circuit that connects the actuator coil to the potential of the power supply and a reference potential. This closure has the effect of allowing current to flow into the coil to supply current to it so that tripping can occur.

[0014] Typically, these circuit breakers also include a control lever that protrudes from the circuit breaker housing and connects to the main contacts, which can be moved by the disconnecting mechanism to allow manual tripping of the circuit breaker.

[0015] Furthermore, in this type of circuit breaker, the electronic processing unit is also configured to check the electrical state of the actuator coil. To perform this check, current must be supplied to the coil—that is, a current lower than its rated trip current, or a current low enough not to cause a trip—which is done by a monitoring circuit for monitoring the electronic processing unit.

[0016] The problem encountered by circuit breakers with electronic trip control is the electromagnetic interference between the components that make up the circuit breaker. Specifically, the integration constraints in this type of protection device require that the components be arranged in a small and compact volume, that is, close to each other. As a result, the interference between these components increases, specifically the electromagnetic influence on the coil generated by at least one current path. Specifically, at least one current path is typically located near the coil and is oriented at least partially perpendicular to or transverse to the actuator axis, such that the current path can generate a magnetic field opposite to the holding force of the magnet, which then has the effect of causing the core to move and thus tripping the circuit breaker. Therefore, at least one current path or another external magnetic or electromagnetic influence can lead to a circuit breaker failure through unexpected tripping. The consequence of such a failure is selective loss. Summary of the Invention

[0017] The object of the present invention is to overcome these disadvantages by providing a circuit breaker with electronic trip control, which can suppress magnetic effects that may be applied to the coil and cause the circuit breaker to trip unexpectedly, and specifically suppress magnetic effects from at least one current path (specifically when the current path extends at least partially transverse to or perpendicular to the axis of the actuator).

[0018] Therefore, according to the invention, a circuit breaker with electronic trip control, the circuit breaker being traversed by at least one current path and capable of ensuring protection against at least one short-circuit type fault in a circuit connected to the current path, the circuit breaker includes a current detector capable of detecting current flowing in the current path or at least one of the current paths and capable of issuing an acquisition signal representing the current; an electronic tripper including an electronic processing unit configured to process the acquisition signal and issue a trip control signal when a trip threshold has been exceeded; an actuator driven by the trip control signal to trip and including a coil; a disconnecting mechanism actuated by the actuator to disconnect at least one main contact, thereby interrupting the current in the current path; and a power supply. Its key feature is that the circuit breaker further includes a suppression circuit for suppressing the magnetic effects on the actuator that may cause unintended tripping, which is capable of short-circuiting the coil when the circuit is controlled to be in a closed state to perform the suppression; and of not short-circuiting the coil when the circuit is controlled to be in an open state; and its key feature is that the electronic processing unit is also configured to control the suppression circuit and coordinate the transmission of the trip control signal with the control of the suppression circuit so as to prevent the coil from being short-circuited while a tripping occurs.

[0019] According to a particular feature of this circuit breaker, at least one current path that may exert a magnetic effect on the coil extends at least partially transversely or perpendicularly to the axis of the actuator. Attached Figure Description

[0020] The invention will be better understood from the following description relating to preferred embodiments, which are given by way of non-limiting example and explained with reference to the accompanying schematic diagrams, wherein:

[0021] Figure 1 This is a functional block diagram of a circuit breaker with electronic trip control according to the present invention;

[0022] Figure 2 It shows Figure 1 The circuit diagram shown is of the electronic tripper and electromagnetic actuator of the circuit breaker, which also includes a monitoring circuit for monitoring the actuator.

[0023] Figure 3 A preferred embodiment of the present invention is shown. Figure 2 The circuit diagram shown includes a delay circuit in the electronic trip unit;

[0024] Figure 4 It shows Figure 3 The circuit diagram shown is a detailed circuit diagram of the circuit breaker, excluding the actuator;

[0025] Figure 5 yes Figure 1 or Figure 3 The diagram shows a cross-sectional view of the actuator of the tripping device, which is positioned above one of three current paths oriented perpendicular to the actuator's axis;

[0026] Figure 6 Timing diagrams are shown for monitoring the state of the actuator via a monitoring circuit and for controlling both the short-circuit switch and the drive switch.

[0027] Figure 7 A timing diagram illustrating the open or closed states of two switches of a circuit breaker according to an embodiment of the present invention and the simultaneous control of the switches is shown, excluding delay circuits; and

[0028] Figure 8 It shows Figure 7 The timing diagram shown includes a delay circuit. Detailed Implementation

[0029] Figures 1 to 8A circuit breaker with an electronic tripping device according to the invention is provided, the circuit breaker being traversed by at least one current path L1, L2, L3, and capable of ensuring protection against at least one short-circuit type fault occurring in a circuit connected to said current path L1, L2, L3 or each of said current paths L1, L2, L3, the circuit breaker comprising:

[0030] A current detector D is capable of detecting current flowing in current paths L1, L2, L3, or current flowing in at least one of current paths L1, L2, L3, and capable of emitting an acquisition signal representing said current. For this purpose, the current detector D may include: at least one sensor D0 capable of detecting current flowing in said current path L1, L2, or L3, and a regulating circuit D1 that emits an acquisition signal representing the current detected by sensor D0;

[0031] Electronic trippers 3, I2, 4, and 5 include an electronic processing unit 3, which is configured to process the acquisition signal emitted by the detector D and emit a trip control signal when a trip threshold has been exceeded.

[0032] Actuator 1, driven to trip by the trip control signal, and includes coil 10, specifically an electromagnetic coil type coil; and

[0033] The disconnecting mechanism, also known as the locking mechanism, can be actuated by the actuator 1 to disconnect at least one main contact C1, C2, C3, which can interrupt the current in the current path L1, L2, L3 or the current in one of the current paths L1, L2, L3.

[0034] Power supply A;

[0035] Power supply A may or may not be integrated into electronic trippers 3, I2, 4, and 5, and provides energy to the coil 10 of electronic processing unit 3 and actuator 1, and, where appropriate, to other electrical or electronic components or parts that constitute the circuit breaker and require such power, i.e., providing current and / or voltage. Power supply A may be implemented by at least one of current paths L1, L2, and L3, for example by means of a current transformer D', which may include the current transformer D' and is functionally connected to the current path L1, L2, or L3.

[0036] According to the present invention, such a circuit breaker further includes suppression circuits I1, 2, 2' for suppressing magnetic effects on actuator 1 that may cause unexpected tripping. The suppression circuits I1, 2, 2' are capable of short-circuiting coil 10 to perform suppression when the circuit is controlled to be closed, and are capable of not short-circuiting coil 10 when the circuit is controlled to be open.

[0037] According to the present invention, magnetic influence should be understood as magnetic influence or electromagnetic influence.

[0038] Still according to the present invention, the electronic processing unit 3 is further configured to control the suppression circuits I1, 2, 2' and coordinate the transmission of the trip control signal with the control of the suppression circuits I1, 2, 2', so as to prevent the coil 10 from being short-circuited when a trip occurs.

[0039] It should be understood that the electronic processing unit 3 can control the suppression circuits I2, 2, 2' to a closed state in a permanent, periodic, or one-time manner. In the case of permanent control, this will be interrupted by the electronic processing unit 3 during tripping so as not to short-circuit coil 10 at the same time as the tripping occurs.

[0040] The short circuit in coil 10, generated by the suppression circuits I1, 2, 2', allows an induced current to flow into coil 10, which is opposite to the cause of its occurrence, thereby compensating for the magnetic effect on actuator 1. The potential magnetic effect on actuator 1 can be generated by at least one of the current paths L1, L2, L3, which are oriented transversely to or perpendicular to the axis X of actuator 1 and positioned close to actuator 1. Figure 1 and Figure 5 Alternatively, the magnetic effect on actuator 1 may be generated by a portion of at least one of the current paths L1, L2, L3, which are oriented transversely to or perpendicular to the axis X of actuator 1 and are positioned close to actuator 1.

[0041] In a preferred embodiment of the suppression circuits I1, 2, 2', the suppression circuit includes a switch I1, referred to as a short-circuit switch, which is controlled by the electronic processing unit 3 and directly connected to the terminals of the coil 10 (in an embodiment not shown in the figures) or via one or more electrical conductors 2, 2' having zero or negligible resistance (see details). Figure 2 and Figure 3 (and / or via electrical components with zero or negligible resistance.)

[0042] Reference Figure 5As can be seen, coil 10 surrounds a movable iron core 11, such as an iron core, a compression spring 12, and a permanent magnet 13, in a known manner. When there is no other field opposite to and exceeding the permanent magnet 13, the permanent magnet 13 holds the iron core 11 in coil 10 by attracting it with its magnetic field, and the iron core 11 compresses the spring 12. During controlled tripping of electronic processing unit 3, tripping current flows into coil 10, which then generates a magnetic field opposite to and exceeding the magnetic field of permanent magnet 13. This has the effect of axially moving the iron core 11 against the attraction of permanent magnet 13 with the assistance of the thrust of spring 12, and also has the effect of actuating the disconnecting mechanism (not shown in the figure).

[0043] Preferably, such as Figure 4 As shown, the short-circuit switch I1 is a transistor, preferably a MOSFET-type field-effect transistor. This transistor is designed to operate in blocking or saturation mode.

[0044] In a known manner, refer more specifically Figure 2 , Figure 3 , Figure 4 , Figure 7 and Figure 8 Electronic trippers 3, I2, 4, and 5 may include switch I2, referred to as drive switch I2, which is controlled by electronic processing unit 3 and can be triggered to close by a trip control signal issued by said electronic processing unit, so as to provide current to coil 10 and perform tripping. Preferably, as from Figure 4 As can be seen from the diagram, the driving switch I2 is a transistor, preferably a MOSFET-type field-effect transistor.

[0045] exist Figure 2 and Figure 3 As can be seen more specifically, one end of coil 10 is connected to the potential Vs of power supply A so as to be supplied with current, and the other end is connected to the reference potential GND via drive switch I2. Drive switch I2 can therefore open or close the circuit supplying current to coil 10 under the control of electronic processing unit 3.

[0046] According to the present invention, the coordination of control enables the control of two switches I1 and I2 to short-circuit the coil 10 of actuator 1 when the coil 10 is not driven / controlled by the electronic processing unit 3. That is, the drive switch I2 is not controlled to be closed. This avoids the following situation: the simultaneous electrical conduction of the switches I1 and I2 causes a short circuit between the power supply of electronic trippers 3, I2, 4, and 5 and actuator 1, thereby causing the circuit breaker to lose its protective function.

[0047] In a preferred embodiment where the short-circuit switch and drive switches I1 and I2 are controlled separately, the electronic processing unit 3 is configured to simultaneously control both switches I1 and I2 to switch them to another closed or open state. Figure 7 and Figure 8 As will be seen below, more specifically, by considering the switching times of the two switches I1 and I2 ( Figure 7 and Figure 8 The simultaneous control is performed using the disconnection time I1, closing time I2, closing time I1, and disconnection time I2, depending on whether it is controlled to be disconnected. Figure 7 and Figure 8 The disconnection time (I1 or I2) is still controlled to be closed ( Figure 7 and Figure 8 The closing time (I1 or I2) in the text can be different.

[0048] However, simultaneously controlling two switches I1 and I2 does not necessarily cause them to switch simultaneously to change the state. Specifically, it is known that the type of switches provided by the present invention can switch from one state to another faster than switching in opposite directions. For example, as Figure 7 and Figure 8 As shown, the switching time (closing time I1 or I2) between switches I1 and I2 from the open state to the closed state is faster than the switching time (opening time I1 or I2) between the closed state and the open state. Therefore, if one of the two switches I1 or I2 changes state, the other switch I1 or I2 will not change state for a shorter period of time. Figure 7 This allows the circuit breaker to detect itself in an inhibited state (which is undesirable) even while coordinating non-tripping control during the period when the suppression circuit is kept closed, where both switches I1 and I2 are closed simultaneously for a short period (a short circuit in the power supply), such as... Figure 7 As shown, when a fault occurs in the circuit connected to the circuit breaker, the short-circuit state of the power supply Vs of coil 10 prevents coil 10 from being driven to force it to trip.

[0049] To overcome this problem, such as Figure 3 , Figure 4 and Figure 8 As shown, in this invention, the electronic trippers 3, I2, 4, and 5 also include a delay circuit 5. This delay circuit is capable of delaying the control of another switch I1 or I2, intended to switch from the first state to the second state, relative to the control of switch I1 or I2 intended to switch from the second state to the first state. This is followed by simultaneous control of both switches I1 and I2 to switch one of them from the first state to the second state and the other switch from the second state to the first state, while taking into account the switching from the first state to the second state. Figure 8The closing time (I1 or I2) is compared to the switching time from the second state to the first state ( Figure 8 The disconnection time (I1 or I2) is fast.

[0050] exist Figure 7 and Figure 8 As can be seen, the first state of switches I1 and I2 can be an open state, and the second state can be a closed state. Then, the switching time (closing time I1 or I2) of each switch I1 and I2 from the open state to the closed state is faster than the switching time (opening time I1 or I2) from the closed state to the open state, and as... Figure 8 As shown, the delay circuit 5 then delays the control of the switches I1 and I2 so as to switch them from the open state to the closed state. This delay is relative to the control of the other switch I1 and I2 so as to switch it from the closed state to the open state, so that the two switches I1 and I2 will not switch to the same closed state at the same time.

[0051] Reference Figure 3 and Figure 4 It can be seen that the delay circuit 5 can be composed of electronic circuits, preferably logic circuits. This logic circuit is connected to the electronic processing unit 3 for its control, and is also connected to the short-circuit switch and drive switches I1 and I2 respectively. The delay circuit 5 can allocate a delay at the output of the electronic processing unit 3 for the control of one of the switches I1 and I2 relative to the control of the other switch I1 and I2. Then, the electronic processing unit 3 simultaneously controls these switches. Figure 3 and Figure 4 More specifically, especially in Figure 4 As can be seen, the logic circuit constituting the delay circuit 5 may include an OR-type first logic gate 50, whose output is connected to a short-circuit switch I1 via a voltage level adapter, and, where appropriate, to the gate of the field-effect transistor constituting the short-circuit switch I1; and the logic circuit may include an AND-type second logic gate 51, whose output is connected to a drive switch I2, and, where appropriate, to the gate of the field-effect transistor constituting the short-circuit switch I1. One input of the first logic gate 50 is connected to the output of an OR-type third gate 52. The two inputs of the third gate 52 constitute the inputs of the logic circuit and are connected to the electronic processing circuit 3 to receive the short-circuit control signal and the drive control signal, respectively. One input of the second gate 51 is connected to one of the two inputs of the OR-type third gate 52. RC circuits 53 and 54 are connected to one of the two other inputs of each logic gate 51 and 52.

[0052] In another embodiment, the delay circuit 5 may also be designed to be integrated into the electronic processing unit 3.

[0053] The circuit breaker may further include a monitoring circuit 4 in a known manner, such that its state and the state of the actuator 1 can be controlled by controlling the electrical continuity through the coil 10, and more specifically, the presence or absence of the function of the control coil 10 can be determined depending on whether continuity is ensured. Figure 2 , Figure 3 and Figure 4 This monitoring circuit 4 is driven by the electronic processing unit 3 and may include a switch I3 controlled by the electronic processing unit 3. Preferably, as shown... Figure 4 As shown, switch I3 is a transistor, preferably a MOSFET-type field-effect transistor.

[0054] Electronic processing unit 3 can be configured to coordinate the control of three switches I1, I2, and I3, and thus coordinate the three functions of short circuit, drive trip, and monitoring. More specifically, electronic processing unit 3 can be configured such that the duration of the opening of short-circuit switch I1 is short enough to prevent unexpected tripping in the event of magnetic interference while monitoring the state of the circuit breaker, and the duration of the opening of short-circuit switch I1 is long enough to allow the monitoring function to detect abnormalities on actuator 1 and, more specifically, abnormalities on coil 10. Figure 6 ).

[0055] By short-circuiting the coil 10 of actuator 1 to allow induced current to flow into coil 10 in a manner opposite to the cause of the induced current, the magnetic trip device installed in this protective device can compensate for and thus suppress the magnetic effects of the current path on actuator 1 and, more specifically, on the magnetic effects on core 11. This device can also be used to compensate for and thus suppress magnetic effects from other electrical components.

[0056] The tripping device according to the invention coordinates the known functions of the drive actuator 1, more specifically the known functions of the coil 10, and / or, where appropriate, the monitoring function, while ensuring a novel short-circuit function that allows suppression of magnetic effects on the actuator 1 that could lead to unintended tripping of the circuit breaker.

[0057] Of course, the present invention is not limited to the embodiments described and shown in the accompanying drawings. Changes are still possible without departing from the scope of protection of the present invention, particularly from the viewpoint of the construction of various elements or by substituting technical equivalents.

Claims

1. A circuit breaker with electronic trip control, wherein, The circuit breaker is traversed by at least one current path and is capable of ensuring protection against at least one short-circuit type fault in the circuit connected to the current path. The circuit breaker includes: A current detector capable of detecting current flowing in the current path or at least one of the current paths, and capable of emitting an acquisition signal indicating the current; An electronic trip unit, comprising an electronic processing unit configured to process the acquired signal and issue a trip control signal when a trip threshold has been exceeded; An actuator, the actuator being driven to trip by the trip control signal and including a coil; and A disconnecting mechanism, actuated by the actuator, to disconnect at least one main contact, thereby interrupting the current in the current path; and power supply; The circuit breaker further includes a suppression circuit for suppressing magnetic effects on the actuator that could cause unexpected tripping. The suppression circuit is capable of short-circuiting the coil when the circuit is controlled to be closed to perform the suppression; and of not short-circuiting the coil when the circuit is controlled to be open. The electronic processing unit is further configured to control the suppression circuit and coordinate the transmission of the trip control signal with the control of the suppression circuit, so as to prevent the coil from being short-circuited when a trip occurs.

2. The circuit breaker according to claim 1, wherein, The suppression circuit includes a short-circuit switch controlled by the electronic processing unit and directly connected to the terminals of the coil, or connected to the terminals of the coil via at least one electrical conductor having zero or negligible resistance and / or via an electrical component having zero or negligible resistance.

3. The circuit breaker according to claim 2, wherein, The short-circuit switch is a transistor.

4. The circuit breaker according to claim 2, wherein, The electronic tripper includes a drive switch controlled by the electronic processing unit and capable of being triggered by a trip control signal issued by the electronic processing unit to close in order to supply current to the coil and perform a trip.

5. The circuit breaker according to claim 4, wherein, The electronic processing unit is configured to simultaneously control the short-circuit switch and the drive switch to switch the short-circuit switch and the drive switch between a closed state and an open state.

6. The circuit breaker according to claim 5, wherein, The electronic tripper also includes a delay circuit that can delay control of another switch from the first state to the second state relative to control of a switch to transition from the second state to the first state, followed by simultaneous control of the short-circuit switch and the drive switch to switch one of the short-circuit switch and the drive switch from the first state to the second state, and the other switch from the second state to the first state, while taking into account that the transition from the first state to the second state is faster than the transition from the second state to the first state.

7. The circuit breaker according to claim 6, wherein, The delay circuit includes electronic circuitry connected to the electronic processing unit for controlling the electronic circuitry, and the electronic circuitry is connected to both the short-circuit switch and the drive switch; the delay circuitry is capable of distributing a delay at the output of the electronic processing unit for the control of one of the switches, the short-circuit switch and the drive switch, relative to the control of the other switch, followed by simultaneous control of the short-circuit switch and the drive switch by the electronic processing unit.

8. The circuit breaker according to any one of claims 1 to 7, wherein, The circuit breaker also includes a monitoring circuit for monitoring the actuator by checking the electrical continuity of the coil to which it is functionally connected. The monitoring circuit is driven by the electronic processing unit and is further configured to not perform the monitoring while the suppression circuit is controlled to the closed state to short-circuit the coil.

9. The circuit breaker according to any one of claims 1 to 7, wherein, At least one current path that may have a magnetic effect on the coil extends at least partially transversely to or perpendicular to the axis of the actuator.

10. The circuit breaker according to claim 3, wherein, The transistor is a MOSFET type field-effect transistor.

11. The circuit breaker according to claim 4, wherein, The drive switch is a transistor.

12. The circuit breaker according to claim 11, wherein, The transistor is a MOSFET type field-effect transistor.

13. The circuit breaker according to claim 6, wherein, The first state is the open state, and the second state is the closed state.

14. The circuit breaker according to claim 7, wherein, The electronic circuit is a logic circuit.

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