Method for detecting degradation of a switching device

Abstract

A method is proposed for detecting a degradation of a switching device (30) comprising:- a movable electrical contact (10),- a control mechanism (4) comprising:- a drive element (9) for the movable contact (10)- an elastic member (7) linked to the drive element (9),- an unlocking member (8) configured to release the elastic member (7) so as to move the contact (10) so as to open an electrical circuit (50),,- an actuator (1) configured to move the unlocking member (8),the method comprising the steps:(i) controlling the actuator (1),(ii) determining a duration (D) between a first instant (t1) corresponding to a predetermined position (P1) of the unlocking member (8) and a second instant (t2) corresponding to a predetermined position (P2) of the drive element (9),(v) carrying out a set of successive commands of the actuator (1), so as to obtain a set (E) of values ​​of the duration (D),(vi) determining a degradation of the unlocking member (8) of the switching device (30) from the evolution of the values ​​of the assembly (E). Abstract figure: Figure 5,

Description

Title of the invention: Method for detecting degradation of a switching device Technical field

[0001] The present invention relates to the field of switching devices for electrical equipment, for example for low and medium voltage electrical equipment. The switching device may for example be a circuit breaker. Prior art

[0002] A low or medium voltage switching device may comprise one or more actuators, for example of the electromagnetic type, for triggering the opening of an electrical circuit. For this, the actuator may unlock a spring control mechanism, for moving a movable electrical contact, so as to open or close the electrical circuit. In the case of a circuit breaker, the opening of the electrical circuit is carried out in the event of the appearance of a fault in the electrical circuit. The fault may be, for example, a short circuit between two phases, or between a phase and earth.

[0003] When the actuator is of the electromagnetic type, it comprises a movable magnetic core and a control coil. Under the action of an electric current flowing through the control coil, the magnetic core moves. The magnetic core is mechanically coupled to a drive element acting on the movable electrical contacts so as to be able to open or close the electrical circuit. Closing the circuit allows a load to be energized.

[0004] In order to ensure the safety of the electrical network and of people, it is important to be able to check the proper functioning of switching devices throughout their lifetime. A switching device is generally subject to the effects of aging which can gradually degrade its electrical or mechanical functions, and ultimately render it inoperative. It is therefore important for users to be able to monitor the evolution of the state of the switching device. In particular, it is desirable to be able to monitor the state of the control mechanism between the actuator and the moving contacts, and in particular to be able to detect a deterioration of this control mechanism. Users can thus intervene to repair or change the control mechanism at an appropriate time in the management of the electrical network. Summary

[0005] To this end, the invention proposes a method for detecting degradation of a switching device comprising: - a movable electrical contact between a closed position of an electrical circuit and an open position of the electrical circuit, - a control mechanism comprising: — a drive element configured to move the movable electrical contact so as to open an electrical circuit, — an elastic member connected to the drive element, — an unlocking member configured to move from a locking position in which the elastic member is held in a tensioned state to a release position in which the elastic member is free to relax so as to move the electrical contact from the closed position to the open position of the electrical circuit, or from the open position to the closed position, - an actuator configured to move the unlocking member from the locking position to the release position, the method comprising the steps: (i) controlling the actuator so as to move the unlocking member from the locking position to the release position, (ii) determining a first instant corresponding to a predetermined position of the unlocking member, (iii) determining a second instant corresponding to a predetermined position of the drive element, (iv) determining a time elapsed between the first instant and the second instant, (v) iterating steps (i) to (iii) for a set of successive commands of the actuator, so as to obtain a set of values ​​of the time elapsed between the first instant and the second instant, (vi) determine a degradation of the unlocking member of the switching device from the evolution of the values ​​of the assembly during successive commands of the actuator.

[0006] The method for detecting degradation of the switching device is a method for detecting a change in the behavior of the control mechanism of the switching device due to the aging of its components. The aging of the components includes, for example, wear, deformations, the effect of corrosion, the change in the tribological properties of the components. The time elapsed between the first instant and the second instant corresponds to a reaction time of the unlocking device. Monitoring the evolution of the value of the duration, i.e. how the duration evolves during the life of the switching device, makes it possible to monitor the evolution of the behavior of the control mechanism of the switching device during its use. In the case where the unlocking member operates nominally, the values ​​of the assembly do not change significantly during successive actuations of the switching device. In other words, the different values ​​of the assembly are substantially constant. Conversely, a progressive degradation of the control mechanism tends to cause a change in the values ​​during successive actuations, in particular a fluctuation of these values. The values ​​of the assembly are no longer substantially constant and exhibit a significant fluctuation. This progressive change makes it possible to detect a degradation of the unlocking member. The method for detecting degradation of the switching device is a method which also makes it possible to anticipate the occurrence of a fault in the switching device. Indeed, uncorrected degradation of the switching device can ultimately lead to the appearance of a fault, and this fault can thus be anticipated.

[0007] The features listed in the following paragraphs can be implemented independently of each other or in any technically possible combination:

[0008] In step (vii), the evolution of the values ​​of the set may be a fluctuation of the values ​​of the set during successive commands of the electromagnetic actuator.

[0009] According to one embodiment, the electrical contact is movable between a position for closing an electrical circuit and a position for opening the electrical circuit, and a relaxation of the elastic member moves the electrical contact from the position for closing to the position for opening the electrical circuit. The control mechanism thus makes it possible to interrupt the flow of electric current in the circuit.

[0010] According to another embodiment, the electrical contact is movable between an open position of an electrical circuit and a closed position of the electrical circuit, and a relaxation of the elastic member moves the electrical contact from the open position to the closed position of the electrical circuit. The control mechanism thus allows the circulation of electric current in the circuit.

[0011] The set of values ​​of the time elapsed between the first instant and the second instant is obtained by a succession of consecutive actuations of the switching device.

[0012] Each value of the set of values ​​of the time elapsed between the first instant and the second instant corresponds to a distinct actuation of the switching device.

[0013] Each actuation of the switching device corresponds to a command of the actuator.

[0014] The switching device may be a circuit breaker.

[0015] The switching device may be a switch.

[0016] The switching device may be a disconnector.

[0017] According to one embodiment, the actuator is an electromagnetic actuator.

[0018] The electromagnetic actuator comprises an electromagnet.

[0019] The electromagnetic actuator comprises a control coil and a magnetic core configured to move under the action of a magnetic field created by a flow of electric current in the control coil.

[0020] The magnetic core is for example mobile in translation.

[0021] The unlocking member is linked to a magnetic core of the electromagnetic actuator.

[0022] According to another embodiment, the actuator comprises a push button that can be manually activated by an operator. The unlocking member includes a position indicator.

[0023] The position indicator provides a two-level signal.

[0024] The position indicator is a two-state electrical switch.

[0025] The predetermined position of the unlocking member making it possible to determine the first instant may be an equilibrium position of the unlocking member.

[0026] The predetermined position of the unlocking member making it possible to determine the first instant may be a transient position of the unlocking member.

[0027] The predetermined position of the drive element for determining the second instant may be a transient position of the drive element.

[0028] The elastic member is configured to apply a driving force to the electrical contact.

[0029] The elastic member may be a spring, for example a spiral spring or a helical spring.

[0030] The drive element may be rotatable.

[0031] The drive element can be connected to the movable contact by a connecting rod.

[0032] Measuring a current flowing in the electromagnetic actuator means measuring the intensity of the electric current flowing in the electromagnetic actuator.

[0033] The current flowing in the electromagnetic actuator can be detected by a sensor for measuring the current flowing in the electromagnetic actuator.

[0034] The current flowing in the electromagnetic actuator can be sampled, for example with a sampling frequency between 1 kHz and 100 kHz.

[0035] The actuator is configured to trigger a movement of the movable electrical contact in order to open or close the electrical circuit.

[0036] When the switching device is a circuit breaker, the electromagnetic actuator is configured to trigger an opening of the electrical circuit in the event of a fault on the electrical circuit.

[0037] According to an embodiment of the proposed detection method, in which the actuator is an electromagnetic actuator, the method comprises the sub-steps: - measure a current flowing in the electromagnetic actuator when the switching device is actuated, - determine the first instant corresponding to a predetermined position of the unlocking member from the temporal variations of the measured current.

[0038] The proposed method thus does not require the installation of any additional sensor, such as a sensor for the movement of the electrical contact or a sensor for the movement of an element of the actuating mechanism.

[0039] The proposed method comprises a sub-step of determining the temporal variations of the measured current.

[0040] The electromagnetic actuator comprises a control coil and a magnetic core configured to move under the action of a magnetic field created by a flow of electric current in the control coil. The predetermined position of the unlocking member corresponding to the first instant is a position of maximum displacement of the magnetic core.

[0041] According to one aspect of the detection method, the first instant corresponding to a predetermined position of the unlocking member is an instant corresponding to a local minimum value of the electric current flowing in the electromagnetic actuator.

[0042] The first instant can be determined from the time evolution of the intensity of the current flowing in the control coil, and coincides with the instant when the current passes through a local minimum value.

[0043] According to another embodiment of the proposed detection method, in which the actuator comprises a push button manually actuated by an operator and in which the unlocking member comprises a position indicator, the method comprises the sub-steps: - measure an electrical signal from the position indicator, - determine the first instant corresponding to a predetermined position of the unlocking member from the temporal variations of the electrical signal of the position indicator.

[0044] The instant corresponds to a change in the electrical state of the position indicator. The instant is a time reference indicating that the action exerted on the push button has been transmitted to the unlocking device.

[0045] According to an embodiment of the detection method, the predetermined position of the drive element corresponding to the second instant is an intermediate displacement position of the drive element. The intermediate displacement position is between a first extreme position in which the movable electrical contact is in the closed position and a second extreme position in which the movable electrical contact is in the open position.

[0046] An angular displacement stroke of the drive element is for example between 40° and 60°.

[0047] According to one embodiment of the detection method, a displacement stroke of the drive element between the first extreme position and the predetermined position corresponding to the second instant is between 5% and 15% of a total displacement stroke of the drive element.

[0048] The initial part of the movement stroke of the drive element is thus used to determine the second instant serving as a reference. The detection sensitivity of the proposed method is thus improved.

[0049] The detection method may comprise the sub-steps: - measure a position of the drive element when the switching device is actuated, - determine the second instant corresponding to the predetermined position of the drive element from the measured position of the drive element.

[0050] According to one embodiment of the proposed detection method: - the control mechanism comprises a position sensor configured to detect a magnetic field, - the drive element comprises a plurality of magnetic elements configured to pass successively in front of the position sensor during a movement stroke of the drive element.

[0051] The magnetic elements may be permanent magnets.

[0052] The position sensor may be a Hall effect sensor.

[0053] The magnetic elements are for example arranged on a part of a periphery of the drive element.

[0054] The magnetic elements may be arranged in a plane perpendicular to an axis of rotation of the drive element.

[0055] The magnetic elements may be identical.

[0056] An angular gap between two consecutive magnetic elements can be constant.

[0057] The drive element comprises, for example, four magnetic elements.

[0058] According to one embodiment, the unlocking member comprises a half-moon rotating mobile.

[0059] The half-moon is actuated by the magnetic core of the electromagnetic actuator.

[0060] The unlocking member may comprise an intermediate lever comprising a first portion configured to cooperate with the half-moon and comprising a second portion configured to cooperate with the drive element.

[0061] According to one embodiment, the detection method comprises the sub-step: - calculating a value of a statistical parameter representative of a fluctuation of the values ​​of the set of values ​​of the duration elapsed between the first instant and the second instant, - determine a degradation of the unlocking organ from the calculated value of the statistical parameter.

[0062] According to an example of implementation of the detection method, the statistical parameter representative of a fluctuation of the values ​​of the set of values ​​of the duration elapsed between the first instant and the second instant comprises a difference between: - a current value of the time elapsed between the first instant and the second instant, determined for a current actuation of the switching device, and - an average value of the values ​​of the time elapsed between the first instant and the second instant obtained for a predetermined number of actuations preceding the current actuation of the switching device.

[0063] The average value may be a sliding average calculated from the values ​​corresponding to the actuations preceding the current actuation, and comprising a number of values ​​equal to the predetermined number of actuations.

[0064] According to an example of implementation of the detection method, the statistical parameter representative of a fluctuation of the values ​​of the set of values ​​of the time elapsed between the first instant and the second instant comprises a standard deviation of the values ​​of the time elapsed between the first instant and the second instant determined for a set of actuations of the switching device carried out under reference conditions corresponding to a new state of the circuit breaker.

[0065] The set of actuations of the switching device carried out under reference conditions comprises for example 20 successive actuations of the switching device.

[0066] The proposed method thus comprises a calibration phase making it possible to quantify the nominal variations in the value of the time elapsed between the first instant and the second instant during actuation of the switching device. These nominal variations correspond to the variations observed in a reference state in which the switching device has neither assembly fault nor degradation due to wear.

[0067] The reference state corresponds for example to a new state of the switching device.

[0068] The proposed method comprises a measurement phase in which the variations in the value of the time elapsed between the first instant and the second instant are analyzed.

[0069] The measurement phase follows the calibration phase.

[0070] The measurement phase is carried out throughout the duration of use of the device. switching.

[0071] According to an example of implementation of the proposed detection method, the statistical parameter representative of a fluctuation in the duration elapsed between the first instant and the second instant is equal to the ratio of: - the difference between a current value of the time elapsed between the first instant and the second instant and the average value of the values ​​of the time elapsed between the first instant and the second instant obtained for a predetermined number of actuations preceding the current actuation, and - the standard deviation of the values ​​of the time elapsed between the first instant and the second instant determined for a set of actuations of the switching device carried out under reference conditions corresponding to a new state of the switching device.

[0072] The proposed statistical parameter allows robust detection of possible degradation of the unlocking member of the switching device, while being simple to implement. In particular, the necessary calculations are easily carried out in real time, which allows rapid detection of degradation.

[0073] The statistical parameter representing a fluctuation in the duration elapsed between the first instant and the second instant can thus be equal to:

[0074] [Math.l] p(i)^-£ÇÆ= ly V j Dr™- i With Di the determined value of the duration D for an actuation of rank i, P(i) the calculated value of the statistical parameter P for the actuation of rank i, M the number of actuations taken into account to determine an average value, K a number of actuations carried out under reference conditions corresponding to a new state of the switching device.

[0075] According to one aspect of the proposed detection method, a degradation of the unlocking member is determined when the absolute value of the statistical parameter representative of a fluctuation in the time elapsed between the first instant and the second instant instant is greater than a first predetermined positive threshold.

[0076] The value chosen for the first predetermined threshold makes it possible to adjust the sensitivity of the proposed detection method.

[0077] The first predetermined threshold is for example between 2 and 3.

[0078] According to an exemplary embodiment of the detection method, the degradation of the unlocking member is classified into a first type of degradation, called minor degradation, when the absolute value of the statistical parameter representative of a fluctuation in the time elapsed between the first instant and the second instant is greater than a first predetermined positive threshold and less than a second predetermined positive threshold.

[0079] The second predetermined threshold is for example between 4 and 5.

[0080] According to an exemplary embodiment of the detection method, the degradation of the organ unlocking is classified into a second type of degradation, called major degradation, when the criterion representing a fluctuation in the time elapsed between the first instant and the second instant is greater than the second predetermined threshold.

[0081] The statistical parameter P used thus allows a quantification of the degradation, and not only the presence or absence of degradation.

[0082] The detection method may comprise a step of emitting an alert signal in response to a determination of degradation of the unlocking member.

[0083] The emitted alert signal allows users to plan and carry out a maintenance or replacement operation of the switching device.

[0084] No alert signal is emitted when no degradation has been determined. In other words, no alert is emitted when the proposed method indicates that the unlocking member is free from degradation.

[0085] The invention also relates to a switching apparatus comprising: - a movable electrical contact between a closed position of an electrical circuit and an open position of the electrical circuit, - a control mechanism comprising: — a drive element configured to move the movable electrical contact so as to open an electrical circuit, — an elastic member connected to the drive element, — an unlocking member configured to move from a locking position in which the elastic member is held in a tensioned state to a release position in which the elastic member is free to relax so as to move the electrical contact from the closed position to the open position of the electrical circuit, - an actuator configured to move the unlocking member from the locking position to the release position, - an electronic control unit configured to implement the degradation detection method as described previously.

[0086] The switching device may be a circuit breaker, or a switch, or a disconnector. Brief description of the drawings

[0087] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0088] [Fig-1] is a schematic view of an electrical circuit equipped with a communication device mutation, the electrical circuit being in the closed position,

[0089] [Fig.2] is a schematic view of an electrical circuit equipped with a switching device, the electrical circuit being in the open position,

[0090] [Fig.3] is a schematic view of the control mechanism of a switching device according to a first embodiment, the electrical circuit being in the closed position,

[0091] [Fig.4] is a schematic view of the control mechanism of the switching device of [Fig.3], the electrical circuit being in the open position,

[0092] [Fig.5] illustrates the temporal evolution of several operating parameters of the switching device of figures 3 and 4, during its actuation,

[0093] [Fig.6] is a time diagram illustrating the method according to the invention,

[0094] [Fig.7] is a block diagram illustrating different steps of the method according to the invention,

[0095] [Fig.8] is a schematic view of the control mechanism of a switching device according to a second embodiment, the electrical circuit being in the closed position,

[0096] [Fig.9] is a schematic view of the control mechanism of the switching device of [Fig.7], the electrical circuit being in the open position. Description of the embodiments

[0097] In order to facilitate the reading of the figures, the different elements are not necessarily represented to scale. In these figures, identical elements bear the same references. Certain elements or parameters may be indexed, that is to say designated for example by first element or second element, or even first parameter and second parameter, etc. This indexing is intended to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another and the names may be interchanged. When it is specified that a subsystem comprises a given element, this does not exclude the presence of other elements in this subsystem. Similarly, when it is specified that a subsystem comprises a given element, it is understood that the subsystem comprises at least this element.

[0098] [Fig.l] shows schematically an electrical circuit 50. The electrical circuit 50 comprises three electrical conductors 20, 21, 22, each conductor corresponding to a phase of a medium voltage three-phase network.

[0099] The electrical circuit 50 comprises a switching device 30.

[0100] The switching device 30 may be a circuit breaker. Alternatively, the switching device 30 may be a switch. According to another example of application, the switching device 30 may be a disconnector.

[0101] [Fig.l] and [Fig.2] respectively illustrate, in a schematic manner, two states of the switching device 30.

[0102] The switching device 30 comprises an electrical contact 10 movable between a closing position F of an electrical circuit 50 and an opening position O of the electrical circuit 50. The switching device 30 also comprises a control mechanism 4 comprising: - a drive element 9 configured to move the movable electrical contact 10 so as to open an electrical circuit 50, - an elastic member 7 linked to the drive element 9, - an unlocking member 8 configured to move from a locking position V in which the elastic member 7 is held in a tensioned state to a release position L in which the elastic member 7 is free to relax so as to move the electrical contact 10 from the closed position F to the open position O of the electrical circuit 50. The switching device 30 further comprises an actuator 1 configured to move the unlocking member 8 from the locking position V to the release position L. The switching apparatus 30 also comprises an electronic control unit 25 configured to implement the degradation detection method which will be described in detail below.

[0103] The elastic member 7 is configured to apply a driving force to the electrical contact 10. The elastic member 7 may be a spring, for example a spiral spring or a helical spring.

[0104] The actuator 1 is configured to trigger a movement of the movable electrical contact 10 in order to open or close the electrical circuit 50. In fact, the actuator 1 makes it possible to unlock the control mechanism 4 in order to move the movable contact 10 and thus open the electrical circuit 50, or close it.

[0105] In [Fig.l], the movable contacts 10, 11, 12 are in the closed position, that is to say that an electric current can flow in the electrical circuit 50. The sign F indicates the closed position of the movable contact 10. The elastic member 7 is in the stretched state. The elastic member 7 is held in the stretched state by the unlocking member 8. The drive element 9 is blocked by the unlocking member 8.

[0106] The opening of the electrical circuit 50 is carried out in the following manner: Under the action of the actuator 1, the unlocking member 8 is moved into a release position L in which the drive element 9 is no longer blocked by the unlocking member 8. The drive element 9 can move under the action of the drive force applied by the elastic member 7, which was in a stretched state and is free to relax. The drive element 9 thus moves the electrical contact 10 from the closed position F to the open position O of the electrical circuit 50. The three movable contacts 10, 11, 12 are mechanically coupled, so that the three contacts 10, 11, 12 jointly move into the open position when the control mechanism 4 is unlocked. [Fig.2] shows schematically the position of the different elements once the movable contacts 10, 11, 12 have been moved to the open position of the electrical circuit 50.

[0107] According to the embodiment illustrated in [Fig.1] and [Fig.2], the actuator 1 is an electromagnetic actuator.

[0108] The electromagnetic actuator 1 comprises an electromagnet. The electromagnetic actuator 1 comprises a control coil 2 and a magnetic core 3 configured to move under the action of a magnetic field created by a flow of electric current in the control coil 2. The magnetic core 3 is for example mobile in translation.

[0109] The unlocking member 8 is linked to the magnetic core 3 of the electromagnetic actuator 1. A movement of the magnetic core 3 of the electromagnetic actuator 1 therefore causes a movement of the unlocking member 8.

[0110] When the switching device 30 is a circuit breaker, the electromagnetic actuator 1 is configured to trigger an opening of the electrical circuit 50 in the event of the presence of a fault on the electrical circuit 50.

[0111] According to another embodiment, illustrated in Figures 8 and 9, the actuator 1 comprises a push button 32 that can be manually actuated by an operator. When the operator wishes to trigger an opening of the electrical circuit 50, the operator presses the push button 32, which is mechanically linked to the unlocking member 8. The unlocking member 8 is thus unlocked by the action of the operator on the push button 32.

[0112] In this embodiment, the unlocking member 8 comprises a position indicator 33.

[0113] The proposed method aims to detect a degradation of the switching device 30, that is to say to detect a change in the behavior of the control mechanism 4 of the switching device 30, and in particular of the unlocking member 8, due to the aging of its components. The aging of the components includes for example wear, deformations, the change in the magnetic performances, the change in the tribological properties of the components.

[0114] A method for detecting degradation of a switching device 30 is thus proposed, comprising: - an electrical contact 10 movable between a closing position F of an electrical circuit 50 and an opening position O of the electrical circuit 50, - a control mechanism 4 comprising: — a drive element 9 configured to move the movable electrical contact 10 so as to open an electrical circuit 50, — an elastic member 7 connected to the drive element 9, — an unlocking member 8 configured to move from a locking position V in which the elastic member 7 is held in a tensioned state to a release position L in which the elastic member 7 is free to relax so as to move the electrical contact 10 from the closed position F to the open position O of the electrical circuit 50, or from the open position O to the closed position F, - an actuator 1 configured to move the unlocking member 8 from the locking position V to the release position L, the process comprising the steps: (i) control actuator 1, (ii) determining a first instant tl corresponding to a predetermined position PI of the unlocking member 8, (iii) determining a second instant t2 corresponding to a predetermined position P2 of the drive element 9, (iv) determine a duration D elapsed between the first instant tl and the second instant t2, (v) iterate steps (i) to (iii) for a set of successive commands of the actuator 1, so as to obtain a set E of values ​​of the duration D elapsed between the first instant t1 and the second instant t2, (vi) determine a degradation of the unlocking member 8 of the switching device 30 from the evolution of the values ​​of the assembly E during the successive commands of the actuator 1.

[0115] The duration D elapsed between the first instant tl and the second instant t2 corresponds to a reaction time of the unlocking member 8. Monitoring the evolution of the value of the duration D, that is to say how the duration D evolves during the life of the switching device 30, makes it possible to monitor the evolution of the behavior of the unlocking member of the control mechanism 4 during its use. In the case where the unlocking member of the control mechanism 4 operates nominally, the values ​​of the set E do not change substantially during successive actuations of the switching device 30. In other words, the different values ​​of the set E are substantially constant. Conversely, a progressive degradation of the unlocking member of the control mechanism 4 during the lifetime of use of the switching device 30 tends to cause a change in the values ​​of the set E during successive actuations, in particular a fluctuation of these values.The values ​​of the set E are thus no longer substantially constant, and show a significant change. This progressive change makes it possible to detect a deterioration of the unlocking member 8 of the control mechanism 4. The method for detecting a degradation of the switching device 30 is a method also making it possible to detect a fault in the switching device 30. Indeed, an uncorrected degradation of the switching device 30 can ultimately lead to the appearance of a fault, and this fault can also be detected.

[0116] The opening movement of the movable electrical contact and the closing movement can be carried out in a similar manner. According to an exemplary implementation, the electrical contact 10 is movable between a closed position F of the electrical circuit 50 and an open position O of the electrical circuit 50, and a relaxation of the elastic member 7 moves the electrical contact 10 from the closed position F to the open position O of the electrical circuit 50. The control mechanism 4 thus makes it possible to interrupt the flow of electric current in the circuit 50.

[0117] According to another example of implementation, the electrical contact 10 is movable between an opening position O of an electrical circuit 50 and a closing position F of the electrical circuit 50, and a relaxation of the elastic member 7 moves the electrical contact 10 from the open position O to the closed position F of the electrical circuit 50. The control mechanism 4 thus makes it possible to establish a circulation of electric current in the circuit 50.

[0118] The set E of values ​​of the duration D elapsed between the first instant t1 and the second instant t2 is obtained by a succession of consecutive actuations of the switching device 30. Each value of the set E of values ​​of the duration D elapsed between the first instant t1 and the second instant t2 corresponds to a distinct actuation of the switching device 30.

[0119] Each actuation of the switching device 30 corresponds to a command of the actuator 1. Actuation of the switching device 30 means a change of the electrical contact 10 from the closed position F of the electrical circuit 50 to the open position O of the electrical circuit 50 in response to a command from the actuator 1.

[0120] When the actuator 1 is an electromagnetic actuator, actuation of the switching device 30 is obtained by circulating current in the control coil 2. When the actuator 1 is a push button, actuation of the switching device 30 is obtained by the operator pressing the push button.

[0121] The predetermined position PI of the unlocking member 8 is a first characteristic position making it possible to define a first time reference making it possible to characterize the operation of the control mechanism 4. The predetermined position P2 of the drive element 9 is a second characteristic position making it possible to define a second time reference making it possible to characterize the operation of the control mechanism 4. More precisely, the duration separating these two time references can be a parameter making it possible to determine a degradation of the control mechanism 4 of the switching device 30.

[0122] According to the example illustrated, the predetermined position PI of the unlocking member 8 making it possible to determine the first instant tl may be an equilibrium position of the unlocking member 8. In other words, the unlocking member 8 has a zero speed when the unlocking member 8 is in the predetermined position PI making it possible to determine the first instant tl.

[0123] According to an embodiment not shown, the predetermined position PI of the unlocking member 8 making it possible to determine the first instant t1 may be a transient position of the unlocking member 8. In this case, the unlocking member 8 has a non-zero speed when the unlocking member 8 is in the predetermined position PI making it possible to determine the first instant tl. The first instant tl corresponds to a passage of the unlocking member 8 through the first position PL

[0124] The predetermined position P2 of the drive element 9 making it possible to determine the second instant t2 may be a transient position of the drive element 9. In other words, the drive element 9 has a non-zero speed when the drive element 9 is in the predetermined position P2 making it possible to determine the second instant t2. The second instant t2 corresponds to a passage of the drive element 9 through the second position P2.

[0125] The duration D elapsed between the first instant tl and the second instant t2 corresponds to the duration separating the first instant tl and the second instant t2.

[0126] The way of determining the first instant tl depends on the type of actuator 1. When actuator 1 is an electromagnetic actuator, the determination of the first instant tl is based on a measurement of the current in the electromagnetic actuator 1.

[0127] By measuring a current C flowing in the electromagnetic actuator 1 is meant the fact of measuring the intensity of the electric current flowing in the electromagnetic actuator 1. The current C flowing in the electromagnetic actuator 1 can be detected by a sensor 6 for measuring the current flowing in the electromagnetic actuator 1. The current C flowing in the electromagnetic actuator 1 can be sampled, for example with a sampling frequency between 1 kHz and 100 kHz.

[0128] In the embodiment in which the actuator 1 is an electromagnetic actuator, the method comprises the sub-steps: - measuring a current C flowing in the electromagnetic actuator 1 when the switching device 30 is actuated, - determine the first instant tl corresponding to a predetermined position PI of the unlocking member 8 from the temporal variations of the measured current C.

[0129] The proposed method thus does not require the installation of any additional sensor, such as a sensor for the displacement of the electrical contact or a sensor for the displacement of an element of the actuating mechanism.

[0130] The proposed method can thus comprise a sub-step of determining the temporal variations of the measured current C.

[0131] The electromagnetic actuator 1 comprises a control coil 2 and a magnetic core 3 configured to move under the action of a magnetic field created by a flow of electric current in the control coil 2. The predetermined position PI of the unlocking member 8 corresponding to the first instant tl is a position of maximum displacement of the magnetic core 3.

[0132] In other words, the first instant tl corresponds to an instant when the magnetic core 3 reaches its position of maximum displacement.

[0133] The first instant tl corresponding to a predetermined position PI of the unlocking member 8 is an instant corresponding to a local minimum value of the electric current flowing in the electromagnetic actuator 1.

[0134] The first instant tl can thus be determined from the temporal evolution of the intensity of the current flowing in the control coil 2, and coincides with the instant when the current passes through a local minimum value.

[0135] [Fig.5] illustrates the evolution of several parameters during an actuation of the switching device. In [Fig.5], curve G2 illustrates the temporal evolution of the electric current in the electromagnetic actuator 1 during a command thereof. Curve G2 comprises a first portion zl continuously increasing, a second portion z2 continuously decreasing, the second portion z2 following the first portion zl, a third portion z3 continuously increasing, the third portion z3 following the second portion z2. The instant tl corresponding to the local minimum of the current corresponds to the instant separating the third portion z3 from the second portion z2. The control of the electromagnet is deactivated at time tf, and the portion z4 corresponds to a phase of decrease of the current until reaching a zero value. The current remains zero until the next activation, or control, of the electromagnet.

[0136] A local maximum value il of the current is obtained for a time tm between a time t0 of start of circulation of the electric current in the electromagnetic actuator 1 and a time tl corresponding to a local minimum of the electric current circulating in the electromagnetic actuator 1. The maximum local value il of the current is the value of the current obtained when passing from the first portion zl to the second portion z2. The decrease in current between time tm and time tl is related to the change in the air gap between the moving parts and the fixed parts. Once the air gap no longer changes, the current starts to increase again, which corresponds to the z3 portion of curve G2. From time tl, the electromagnetic actuator 1 has completed its maximum displacement stroke and the position of the magnetic core 3 no longer changes. The electrical control is however maintained until time tf, in order to ensure a holding force.

[0137] When the actuator 1 is a purely mechanical actuator of the push button type, the determination of the first instant tl is based on the signal from a position indicator, also called a position sensor.

[0138] The unlocking member 8 thus comprises a position indicator 33. The position indicator 33 can provide a two-level signal. The position indicator 33 is a contactor with two electrical states. In other words, the signal from the position indicator 33 switches from a first level to a second level when the locking member reaches a certain threshold position.

[0139] Thus, in the embodiment of the proposed detection method, in which the actuator 1 comprises a push button 32 manually actuated by an operator and in which the unlocking member 8 comprises a position indicator 33, the method comprises the sub-steps: - measure an electrical signal from the position indicator 33, - determine the first instant tl corresponding to a predetermined position PI of the unlocking member 8 from the temporal variations of the electrical signal of the position indicator 33.

[0140] The instant tl corresponds to a change in the electrical state of the position indicator 33. The instant tl is a time reference indicating that the action exerted on the push button by the operator has been transmitted to the unlocking device 8.

[0141] [Fig.3] and [Fig.4] illustrate an embodiment of the control mechanism 4 of the switching apparatus 30, in which the actuator 1 is an electromagnetic actuator. In order to simplify the figure, the elastic member 7 is represented in the form of a helical spring. The elastic member 7 can also be a spiral spring.

[0142] In [Fig. 3], the unlocking member 8 is in the locking position V and the spring 7 is held in a compressed state. One end of the spring 7 exerts a force on a fixed stop 18, the other end of the spring exerts a force on the drive element 9.

[0143] The drive element 9 is here movable in rotation. The drive element 9 is connected to the movable contact 10 by a connecting rod 19. The connecting rod 19 is rigid. The connecting rod 19 is pivotally connected to the drive element 9. The connecting rod 19 is in pivot connection with respect to the movable contact 10.

[0144] The unlocking member 8 comprises a half-moon 16 which can rotate. The half-moon 16 has a general shape of a half-cylinder, and includes a flat surface 16-1 extending parallel to the axis of the half-cylinder. The half-moon 16 is actuated by the magnetic core 3 of the electromagnetic actuator 1. By actuated is meant that the half-moon 16 can pivot in response to the movement of the magnetic core 3. The electromagnetic actuator 1 comprises a connecting element 13 connecting the movable magnetic core 3 and the half-moon 16.

[0145] The unlocking member 8 also comprises an intermediate lever 17 comprising a first portion 17-1 configured to cooperate with the half-moon 16 and comprising a second portion 17-2 configured to cooperate with the drive element 9.

[0146] In [Fig. 3], where the unlocking member 8 is in the locking position V, the driving force of the elastic member 7 applied to the driving element 9 is transmitted to the intermediate lever 17 of the unlocking member 8. The half-moon 16 is in the locking position, and blocks the rotation of the intermediate lever 17 because the first portion 17-1 of the intermediate lever 17 interferes with the surface 16-1 of the half-moon 16. The second portion 17-2 blocks the driving element 9, which is thus held in place. The spring 7 is kept compressed between the driving element 9 and the fixed stop 18. When the half-moon 16 leaves its locking position, the first portion 17-1 is no longer held and the force applied at the second portion 17-2 causes the intermediate lever 17 to pivot. The intermediate lever 17 can thus pivot under the action of the driving force of the elastic member 7. The driving element 9 can thus move under the action of the driving force of the elastic member 7. The connecting rod 19, secured to the driving element 9, causes the movable contact 10 to pivot.

[0147] In [Fig.4], the unlocking member 8 is in the release position L. The spring 7 in the relaxed state, after having pivoted the drive element 9 and thus moved the movable electrical contact 10, is in the opening position O. In [Fig.4], the half-moon 16 of the unlocking member 8 is shown in the position PI used to define the first time reference tl.

[0148] According to the illustrated embodiment, the predetermined position of the drive element 9 corresponding to the second instant t2 is an intermediate displacement position of the drive element 9. The intermediate displacement position is between a first extreme position B1 in which the movable electrical contact 10 is in the closed position F and a second extreme position B2 in which the movable electrical contact 10 is in the open position O. [Fig.3] schematizes the first extreme position B1 and [Fig.4] schematizes the second extreme position B2.

[0149] According to the example illustrated, a displacement stroke of the drive element 9 between the first extreme position B1 and the predetermined position P2 corresponding to the second instant t2 is between 5% and 15% of a total displacement stroke CT of the drive element 9. The initial part of the movement stroke of the drive element 9 is thus used to determine the second instant serving as a reference. The detection sensitivity of the proposed method is thus improved.

[0150] The total displacement stroke CT is the distance between the first extreme position B1 and the second extreme position B2 of the drive element 9. In the case where the drive element 9 is rotatable, the de- total CT placement is an angular distance.

[0151] An angular travel CT of movement of the drive element 9 is for example between 40° and 60°. The sign LO denotes a reference indicating the initial position B1 of the drive element 9, and the sign L1 denotes the position of this reference after complete rotation of the drive element 9, when the latter is in position B2. The difference between LO and L1 indicates the rotation stroke CT. The sign L2 designates the position of the reference LO at the moment when the drive element 9 is in the predetermined position P2, corresponding to the second instant t2.

[0152] The detection method may comprise the sub-steps: - measuring a position of the drive element 9 when the switching device 30 is actuated, - determine the second instant t2 corresponding to the predetermined position P2 of the drive element 9 from the measured position of the drive element 9.

[0153] According to the embodiment illustrated here: - the control mechanism 4 comprises a position sensor 14 configured to detect a magnetic field, - the drive element 9 comprises a plurality of magnetic elements 15 configured to pass successively in front of the position sensor 14 during a movement stroke of the drive element 9.

[0154] When the drive element 9 passes from the first extreme position B1 in which the movable electrical contact 10 is in the closed position F to a second extreme position B2 in which the movable electrical contact 10 is in the open position O, the passage of a magnetic element 15 in front of the position sensor 14 generates a change in the electrical state of the position sensor 14. When this magnetic element 15 moves away from the sensor 14, the position sensor 15 returns to the initial electrical state. The rotation of the drive element 9 therefore generates a signal comprising a succession of square pulses, each square pulse corresponding to a distinct magnetic element 15. The magnetic elements 15 may be permanent magnets. Position sensor 14 may be a Hall effect sensor.

[0155] The magnetic elements 15 are arranged on a part of a periphery of the drive element 9. The magnetic elements 15 are here arranged in a plane perpendicular to an axis of rotation of the drive element 9. The magnetic elements 15 are identical in the example illustrated. The elements magnetic 15 can also be different. An angular distance T between two consecutive magnetic elements 15 is constant here. The magnetic elements can also be implanted with an angular distance between two consecutive magnetic elements 15 which is not from one magnetic element to another.

[0156] The drive element 9 comprises, in the illustrated example, four magnetic elements 15. The four magnetic elements 15 are permanent magnets. In [Fig.3] and [Fig.4], the 4 permanent magnets are designated by the signs 15-1, 15-2, 15-3, 15-4. A different number of magnetic elements can of course be used.

[0157] In [Fig.5], curve G3 illustrates the signal provided by the position sensor 14 during the movement of the drive element 9. Time t2 corresponds to the start of the passage of the first magnet 15-1 in front of the position sensor 14. Time t3 corresponds to the start of the passage of the second magnet 15-2 in front of the position sensor 14. Similarly, time t4 corresponds to the start of the passage of the third magnet 15-3 and time t5 corresponds to the start of the passage of the fourth magnet 15-4. The time between the passage of two consecutive magnets is not constant because the speed of movement is not constant. In [Fig.5], curve G1 indicates the signal delivered by a high-resolution position sensor. In other words, this sensor delivers a substantially continuous signal and not a discrete signal. This sensor was mounted solely for experimental purposes for the purposes of validating the proposed method, and is not part of the switching device 30 when the latter is used nominally. The signal of curve G1 is therefore not used by the proposed method. Until time td, the signal is constant, which indicates that the drive element 9 is stationary. The drive element 9 begins to rotate at the time designated by td. The instant t2 at which the position sensor 14 changes electrical state due to the passage of the magnet 15-1 is later than the instant td due to the displacement travel required so that the magnet 15-1 is in a position located opposite the position sensor 14.

[0158] As illustrated in [Fig.5], the predetermined position of the drive element 9 defining the second instant t2 corresponds to the position of passage of the first magnet 15-1 in front of the position sensor 14. The predetermined position PI of the unlocking member 8 defining the first instant tl is the end position of pivoting of the half-moon 16. The time difference between time tl and time t2 defines a duration D.

[0159] [Fig.8] and [Fig.9] illustrate an embodiment of the control mechanism 4 of the switching apparatus 30, in which the actuator 1 is a mechanical actuator of the push button type.

[0160] This embodiment differs from that of figures 3 and 4 by the nature of the actuator 1 and by the presence of the position indicator 33. The push button 32 is connected to the half-moon 16 by a connecting element 13B. For example, the push button 32 is secured to a connecting element 13B connected to the half-moon 16. This connecting element 13B can move the half-moon 16 in a manner similar to that described in the context of the embodiment with electromagnetic actuator, figures 3 and 4.

[0161] The instant tl is determined from the electrical signal delivered by the position indicator 33. The position indicator 33 comprises a pivoting tab 34 held at a distance from a contactor 35 by a spring, not shown. When the half-moon 16 is distant from the pivoting tab 34, as is the case in [Fig.8], the tab is itself distant from the contactor 35 which is in the so-called released state. The position indicator 33 delivers a first signal level. Once the half-moon 16 has pivoted sufficiently, it moves the pivoting tab 34 which presses on the contactor 35 and causes it to leave the released state. The position indicator 33 then delivers a second signal level. The instant corresponding to a transition between the first signal level and the second signal level makes it possible to determine the first instant tl. In this embodiment, the remainder of the control mechanism 4 is identical to the embodiment of Figures 3 and 4, and the determination of the second instant t2 is carried out in the same way.

[0162] The determined duration D is the physical parameter on which the method for detecting a degradation of the control mechanism 4 is based. A statistical treatment is applied to this physical parameter.

[0163] The detection method thus comprises the sub-step: - calculate a value of a statistical parameter P representative of a fluctuation of the values ​​of the set E of values ​​of the duration D elapsed between the first instant tl and the second instant t2, - determine a degradation of the unlocking member 8 from the calculated value of the statistical parameter P.

[0164] According to an example of implementation of the detection method, the statistical parameter P representative of a fluctuation of the values ​​of the set E of values ​​of the duration D elapsed between the first instant tl and the second instant t2 includes a difference between: - a current value of the duration D elapsed between the first instant t1 and the second instant t2, determined for a current actuation of the switching device 30, and - an average value Moy of the values ​​of the duration D elapsed between the first instant t1 and the second instant t2 obtained for a predetermined number M of actuations preceding the current actuation of the switching device 30.

[0165] The average value Moy can be a sliding average calculated from the values ​​corresponding to the actuations preceding the current actuation, and comprising a number of values ​​equal to the predetermined number M of actuations.

[0166] According to an example of implementation of the detection method, the statistical parameter P representative of a fluctuation of the values ​​of the set E of values ​​of the duration D elapsed between the first instant t1 and the second instant t2 comprises a standard deviation of the values ​​of the duration D elapsed between the first instant t1 and the second instant t2 determined for a set of actuations of the switching device 30 carried out under reference conditions corresponding to a new state of the circuit breaker 30.

[0167] The set of actuations of the switching device 30 carried out under reference conditions comprises for example 20 successive actuations of the switching device 30.

[0168] The proposed method thus comprises a calibration phase making it possible to quantify the nominal variations in the value of the duration D elapsed between the first instant t1 and the second instant t2 during the actuation of the switching device 30. These nominal variations correspond to the variations observed in a reference state in which the switching device 30 has neither assembly fault nor degradation due to wear. The reference state corresponds, for example, to a new state of the switching device 30.

[0169] The proposed method comprises a measurement phase in which the variations in the value of the duration D elapsed between the first instant t1 and the second instant t2 are analyzed. The measurement phase follows the calibration phase. The measuring phase is carried out throughout the duration of use of the switching device 30.

[0170] The values ​​acquired under these reference conditions make it possible to determine the nominal variability of the duration D elapsed between the first instant t1 and the second instant t2. This nominal variability is here characterized by the mathematical quantity equal to the standard deviation of the duration D elapsed between the first instant t1 and the second instant t2. instant t2, calculated for all the measurements carried out under the reference conditions. This nominal variability is characterized from a predetermined number of values ​​corresponding to a predetermined number of actuations. For example, 20 successive actuations carried out in the new condition of the switching device 30 can make it possible to characterize the nominal variability of the quantity used to determine a degradation of the switching device 30.

[0171] [Fig.6] illustrates the values ​​of the duration D between the first instant t1 and the second instant t2, for different actuations of the switching device 30. Part A shows the measurements taken at a first time t_A. Part B of the figure shows the measurements taken at a second time t_B, which is later than t_A.

[0172] The measurement points framed by the box designated by J0 are those carried out under reference conditions corresponding to a new state of the switching device 30. To simplify the figure, only 7 measurement points have been shown. It can be noted that the dispersion of the values ​​of the quantity D is low. The sign EcO designates the standard deviation of the values ​​corresponding to the set of actuations of the switching device 30 carried out under reference conditions, and taken into account for the calibration phase.

[0173] In part A of [Fig.6], the measurement points framed by the box designated by J1 are the points used at time t_A for the measurement phase. As previously, to simplify the figure only 10 measurement points of duration D have been represented. The value Dn, determined at time t_A, is the current value at time t_A, that is to say the most recent value. The dotted horizontal line indicates the average value avg_A of the values ​​taken into account, i.e. those present in the JL frame The arrow designated by e_A illustrates the difference between the current value Dn and the average value avg_A calculated in this example from the 10 measurement points preceding the current measurement Dn.

[0174] In part B of [Fig.6], the measurement points framed by the box designated by J2 are the points used at time t_B for the measurement phase. As previously, 10 measurement points are used in the figure. The value determined at time t_B is the current value at time t_B, i.e. the most recent value. Compared to time t_A, 4 new measurements have been acquired, and the 4 oldest values ​​from frame J1 are not used at time t_B and are not part of frame J2. The dotted horizontal line indicates the average value avg_B of the values ​​taken into account, i.e. those present in frame J2. The arrow designated by e_B illustrates the difference between the current value Dn+4 and the value average avg_B.

[0175] More precisely, the statistical parameter P representative of a fluctuation of the duration D elapsed between the first instant t1 and the second instant t2 is equal to the ratio of: - the difference between a current value Di of the duration D elapsed between the first instant tl and the second instant t2 and the average value Moy of the values ​​of the duration D elapsed between the first instant tl and the second instant t2 obtained for a predetermined number M of actuations preceding the current actuation, and - the standard deviation Ec of the values ​​of the duration D elapsed between the first instant t1 and the second instant t2 determined for a set of actuations of the switching device 30 carried out under reference conditions corresponding to a new state of the switching device 30.

[0176] The proposed statistical parameter P allows robust detection of possible degradation of the unlocking member 8 of the control mechanism 4 of the switching device 30, while being simple to implement. In particular, the necessary calculations are easily carried out in real time, which allows rapid detection of degradation.

[0177] The statistical parameter P representative of a fluctuation of the duration D elapsed between the first instant t1 and the second instant t2 is thus equal to:

[0178] [Math.l] With D; the determined value of the duration D for an actuation of rank i, P(i) the calculated value of the statistical parameter P for the actuation of rank i, M the number of actuations taken into account to determine an average value, K the number of actuations carried out under reference conditions corresponding to a new state of the switching device 30.

[0179] The calculation carried out of the statistical parameter P makes it possible to conclude on the state of the control mechanism 4. A degradation of the unlocking member 8 is determined when the absolute value of the statistical parameter P representative of a fluctuation of the duration D elapsed between the first instant t1 and the second instant t2 is greater than a first predetermined positive threshold SL

[0180] The value chosen for the first predetermined threshold SI makes it possible to adjust the sensitivity of the proposed detection method. The first predetermined threshold SI is for example between 2 and 3.

[0181] According to an exemplary embodiment of the detection method, the degradation of the unlocking member 8 is classified into a first type of degradation, called minor degradation, when the absolute value of the statistical parameter P representative of a fluctuation of the duration D elapsed between the first instant t1 and the second instant t2 is greater than a first predetermined positive threshold S1 and less than a second predetermined positive threshold S2. The second predetermined positive threshold S2 is for example between 4 and 5.

[0182] The degradation of the unlocking member 8 is classified into a second type of degradation, called major degradation, when the absolute value of the parameter D representative of a fluctuation of the duration D elapsed between the first instant t1 and the second instant t2 is greater than the second predetermined threshold S2.

[0183] The statistical parameter P used thus allows a quantification of the degradation, and not only a determination of the presence or absence of degradation.

[0184] The detection method may comprise a step of emitting an alert signal in response to a determination of degradation of the unlocking member 8. The emitted alert signal allows users to plan and carry out a maintenance or replacement operation of the switching device 30.

[0185] The alert signal may be, for example, a code stored in an electronic control unit. Alternatively or additionally, the alert signal may be the lighting of a warning light. Alternatively or additionally, the alert signal may be a display of a message on a control screen. Other types of alert are of course possible.

[0186] No alert signal is emitted when no degradation has been determined. In other words, no alert is emitted when the proposed method indicates that the control mechanism 4 is free from degradation.

Claims

Claims

1. A method of detecting degradation of a switching device (30) comprising: - an electrical contact (10) movable between a closed position (F) of an electrical circuit (50) and an open position (O) of the electrical circuit (50), - a control mechanism (4) comprising: — a drive element (9) configured to move the movable electrical contact (10) so as to open an electrical circuit (50), — an elastic member (7) connected to the drive element (9), — an unlocking member (8) configured to move from a locking position (V) in which the elastic member (7) is held in a tensioned state to a release position (L) in which the elastic member (7) is free to relax so as to move the electrical contact (10) from the closed position (F) to the open position (O) of the electrical circuit (50), or from the open position (O) to the closed position (F), - an actuator (1) configured to move the unlocking member (8) from the locking position (V) to the release position (L), the method comprising the steps: (i) controlling the actuator (1) so as to move the unlocking member (8) from the locking position (V) to the release position (L), (ii) determining a first instant (tl) corresponding to a predetermined position (PI) of the unlocking member (8), (iii) determining a second instant (t2) corresponding to a predetermined position (P2) of the drive element (9), (iv) determine a duration (D) elapsed between the first instant (tl) and the second instant (t2), (v) iterating steps (i) to (iii) for a set of successive commands of the actuator (1), so as to obtain a set (E) of values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2), (vi) determining a degradation of the unlocking member (8) of the switching device (30) from the evolution of the values ​​of the assembly (E) during successive commands of the actuator (1).

2. A detection method according to claim 1, wherein the actuator (1) is an electromagnetic actuator, and in which the method comprises the sub-steps: - measuring a current (C) flowing in the electromagnetic actuator (1) during actuation of the switching device (30), - determining the first instant (tl) corresponding to a predetermined position (PI) of the unlocking member (8) from the temporal variations of the measured current (C).

3. Detection method according to claim 2, wherein the electromagnetic actuator (1) comprises a control coil (2) and a magnetic core (3) configured to move under the action of a magnetic field created by a flow of electric current in the control coil (2), and wherein the predetermined position (PI) of the unlocking member (8) corresponding to the first instant (tl) is a position of maximum movement of the magnetic core (3).

4. Detection method according to claim 2 or 3, in which the first instant (tl) corresponding to a predetermined position (PI) of the unlocking member (8) is an instant (tm) corresponding to a local minimum value of the electric current flowing in the electromagnetic actuator (1).

5. Detection method according to claim 1, in which the actuator (1) comprises a push button (32) manually actuated by an operator and in which the unlocking member (8) comprises a position indicator (33), in which the method comprises the sub-steps: - measuring an electrical signal from the position indicator (33), - determining the first instant (tl) corresponding to a predetermined position (PI) of the unlocking member (8) from the temporal variations of the electrical signal from the position indicator (33).

6. Detection method according to one of the preceding claims, in which the predetermined position of the drive element (9) corresponding to the second instant (t2) is an intermediate displacement position of the drive element (9), the intermediate displacement position being between a first extreme position (B1) in which the movable electrical contact (10) is in the closed position (F) and a second extreme position (B2) in which the movable electrical contact (10) is in the open position (0).

7. A detection method according to the preceding claim, wherein a displacement stroke of the drive element (9) between the first extreme position (Bl) and the predetermined position (P2) corresponding to the second instant (t2) is between 5% and 15% of a total displacement stroke (CT) of the drive element (9).

8. Detection method according to one of the preceding claims, comprising the sub-steps: - measuring a position of the drive element (9) during actuation of the switching device (30), - determining the second instant (t2) corresponding to the predetermined position (P2) of the drive element (9) from the measured position of the drive element (9).

9. Detection method according to one of the preceding claims, wherein: - the control mechanism (4) comprises a position sensor (14) configured to detect a magnetic field, - the drive element (9) comprises a plurality of magnetic elements (15) configured to pass successively in front of the position sensor (14) during a movement stroke of the drive element (9).

10. Detection method according to one of the preceding claims, comprising the sub-step: - calculating a value of a statistical parameter (P) representative of a fluctuation of the values ​​of the set (E) of values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2), - determining a degradation of the unlocking member (8) from the calculated value of the statistical parameter (P).

11. Detection method according to the preceding claim, in which the statistical parameter (P) representative of a fluctuation of the values ​​of the set (E) of values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2) comprises a difference (X) between: - a current value of the duration (D) elapsed between the first instant (tl) and the second instant (t2), determined for a current actuation of the switching device (30), and - an average value (Avg) of the values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2) obtained for a predetermined number (M) of actuations preceding the current actuation of the switching device (30).

12. Detection method according to claim 10 or 11, in which the statistical parameter (P) representative of a fluctuation of the values ​​of the set (E) of values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2) comprises a standard deviation of the values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2) determined for a set of actuations of the switching device (30) carried out under reference conditions corresponding to a new state of the circuit breaker (30).

13. Detection method according to one of claims 10 to 12, in which the statistical parameter (P) representative of a fluctuation of the duration (D) elapsed between the first instant (tl) and the second instant (t2) is equal to the ratio of: - the difference (X) between a current value (Di) of the duration (D) elapsed between the first instant (tl) and the second instant (t2) and the average value (Moy) of the values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2) obtained for a predetermined number (M) of actuations preceding the current actuation, and of - the standard deviation (Ec) of the values ​​of the duration (D) elapsed between the first instant (tl) and the second instant (t2) determined for a set of actuations of the switching device (30) carried out under reference conditions corresponding to a new state of the switching device (30).

14. Detection method according to one of claims 10 to 13, in which the statistical parameter (P) representative of a fluctuation in the duration (D) elapsed between the first instant (tl) and the second instant (t2) is equal to: [Math.l] D-^ ^ = T==^ A' !

15. Detection method according to one of claims 10 to 14, in which a degradation of the unlocking member (8) is determined when the absolute value of the statistical parameter (P) representative of a fluctuation of the duration (D) elapsed between the first instant (t1) and the second instant (t2) is greater than a first predetermined positive threshold (SI).

16. Detection method according to the preceding claim, in which:

17.

18. - the degradation of the unlocking member (8) is classified into a first type of degradation, called minor degradation, when the absolute value of the statistical parameter (P) representative of a fluctuation of the duration (D) elapsed between the first instant (tl) and the second instant (t2) is greater than a first predetermined positive threshold (SI) and less than a second predetermined positive threshold (S2), and in which: - the degradation of the unlocking member (8) is classified into a second type of degradation, called major degradation, when the absolute value of the statistical parameter (P) representative of a fluctuation of the duration (D) elapsed between the first instant (tl) and the second instant (t2) is greater than the second predetermined positive threshold (S2). Detection method according to claim 15 or 16, comprising a step of emitting an alert signal in response to a determination of degradation of the unlocking member (8). Switching apparatus (30) comprising: - an electrical contact (10) movable between a closed position (F) of an electrical circuit (50) and an open position (O) of the electrical circuit (50), - a control mechanism (4) comprising: — a drive element (9) configured to move the movable electrical contact (10) so as to open an electrical circuit (50), — an elastic member (7) linked to the drive element (9), — an unlocking member (8) configured to move from a locking position (V) in which the elastic member (7) is held in a tensioned state to a release position (L) in which the elastic member (7) is free to relax so as to move the electrical contact (10) from the closed position (F) to the open position (O) of the electrical circuit (50), - an actuator (1) configured to move the unlocking member (8) from the locking position (V) to the release position (L), - an electronic control unit (25) configured to implement the degradation detection method according to one of the preceding claims, the switching device (30) being a circuit breaker, or a switch, or a disconnector.

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