EP2254136B1 - Apparatus for the assessment of the integrity of pressed contacts by the variation in the rotation of the pole shaft and its manufacturing process - Google Patents

Description

TECHNICAL AREA

The invention relates to the evaluation of the erosion of pole contacts in a switchgear device by indirect measurement of the rotational displacement of a drive mechanism of the contacts. In particular, the invention relates to a switchgear comprising a pair of movable contacts relative to each other, the movable contact being supported by an arm allowing it an over-stroke in the closed position. The invention also relates to a method for providing a high electrodynamic breaking device with means for verifying the integrity of the contacts.

STATE OF THE ART

A power supply line of an electrical load to be controlled is conventionally provided with at least one switching device which comprises, for each phase, pairs of movable contacts relatively to each other in order to switch the load. The actuation of the contacts can be carried out in different ways; in particular, for certain high-power cut-off devices (in particular greater than 1000 A), used for example in safety at the head end, high electrodynamic resistance is required and the contacts are driven by a lever system coupled to a rotary axis , itself actuated by a toggle mechanism with two pivoting links, as for example described in EP 0 222 645 , EP 0 789 380 or EP 1 347 479 .

The contacts may be arranged directly on the conductors or comprise pellets of suitable material, in particular silver alloy; whatever the technological choice, the contacts wear out more or less during each switching and in particular in the presence of arc. This wear can, after a large number of switching operations, lead to a failure of the switchgear, with consequences on the safety and availability of the installation. To prevent these risks, a solution Usual is to systematically change the contacts, or even the entire cutoff device, after a predetermined number of operations, unrelated to the actual wear of the pellets. These interventions are, however, often too late, for example if one of the switching maneuvers generated a larger electric arc, with the associated risks, either premature, with the costs inherent in the replacement of pellets almost intact.

The ability to evaluate the integrity of the contacts or determine their actual wear in order to deduce information giving the residual life, or the end of life, poles contacts therefore provides an appreciable advantage. For some high power devices and long life, maintenance operations thus regularly provide a visual assessment of the state of the pellets, for example by the establishment of wear indicators on the contacts. This operation can only be done by opening the device, that is to say during maintenance operations immobilizing the installation. For security purposes, in which the switchgear is only tripped occasionally and the contacts are usually kept closed, this type of check is often sufficient. However, for other applications that are developing, such as as a safety device of a wind turbine installation, the number of maneuvers increases, and a higher endurance of the contacts is required: a visual verification of the contacts at predetermined intervals becomes problematic and insufficient.

Various methods have been developed to evaluate the erosion of the contact pellets regularly and / or without decommissioning the apparatus. The document EP 0 878 015 is thus based on the modification of the contact pressure during an opening operation of the breaking device; this type of device however requires the addition of specific means for measuring the switching voltage at a neutral point and the use of an auxiliary switch. The document FR 2 834 120 proposes the study of the evolution of the travel time of the wear stroke of the contacts during a closing movement by current measurement in the control electromagnet; this solution does not apply to circuit breakers that can be opened or closed manually.

The document WO 2007/033913 proposes the measurement of various parameters characterizing the relative movement of the contacts according to that of their actuator, of the electromagnetic type. However, it appears that this technique is only suitable if the speed of the contacts, or the effort required to mobilize them, is variable in time; however, the high-power switching devices tend to have a linear stroke with respect to the time with depression and over-travel of the contacts, which makes this type of method imprecise or even unsuitable.

SUMMARY OF THE INVENTION

Among other advantages, the invention aims to provide a device for verifying the integrity of the contacts simple and suitable for switching devices which a moving contact driven by a rotary axis is depressed at the end of the closing maneuver of the device.

In one aspect, the invention relates to an electrical protection apparatus provided with such a device measuring the variation of the rotation of the drive shaft in the over-stroke phase. The electrical protection apparatus is preferably multipole, and each pole comprises a pair of movable contacts relative to each other between an open position and a closed position. The movable contact is mounted on a support arm comprising two sliding parts relative to each other so that, in the closed position of the contacts, the movable contact can be either in the rest position, the docking position, or position pushed into the support arm. Advantageously, spring means urging the contact in non-recessed rest position, projecting relative to the arm. Preferably, at least one pair of contacts is associated with a pair of arcing contacts which are usually separated from one another but which close transiently upon actuation of the poles; in particular, the support arm of the movable contact comprises an arc contact at its end.

The support arm of the movable contact is driven between the open position and the closed positions by rotation of an axis of the protective device coupled thereto by a bead wire. Preferably, the rotary axis is a pole shaft common to the entire switchgear; the breaking device can in particular be strong electrodynamic resistance, with actuated by a toggle mechanism and reset device. Preferably, the residual rotation of the pole shaft once the contacts are closed, that is to say, the contact position of the moving contacts at the end of travel corresponding to the depression of the moving contact, is the order of 30% of its total rotation during a closing maneuver.

According to the invention, the switching device comprises a contact wear determining device which measures the angle traveled by the rotary axis between the contact position of the pole contacts and the end position of the contact. axis. The determination device is preferably an angular sensor or a rotation sensor, coupled directly to the rotary axis. Advantageously, the rotation sensor is magnetic and operates remotely; in particular, magnet type magnetic means are arranged on the axis, in particular at its end, and detection means are placed on the housing of the cut-off device facing the magnetic means.

In another aspect, the invention relates to a method for equipping a switchgear as presented by a device for measuring the integrity of its contacts by setting up a rotation sensor at one end of the pole tree. The method can be applied for existing devices, and it preferably comprises the securing of magnetic means on one end of the pole shaft and the establishment in front of the magnetic means means for detecting their angular position.

BRIEF DESCRIPTION OF THE FIGURES

• La figure 1A illustre un appareil de coupure de sécurité à tenue électrodynamique élevée dans lequel peut être mis en place un dispositif de détermination de l'usure des contacts selon le principe de l'invention ; les figures 1B et 1C montrent les étapes de fermeture de cet appareil de coupure.
• La figure 2 représente un capteur utilisé dans un mode de réalisation préféré de l'invention.
• Les figures 3A à 3C montrent les étapes d'ouverture d'un appareil de coupure selon un mode de réalisation de l'invention.
• La figure 4 schématise la courbe d'usure des contacts en présence de contacts d'arc.

Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of illustration and in no way limiting, represented in the appended figures.

• The Figure 1A illustrates a safety cut-off apparatus with high electrodynamic resistance in which a device for determining the wear of the contacts according to the principle of the invention can be put in place; the Figures 1B and 1C show the closing steps of this switchgear.
• The figure 2 represents a sensor used in a preferred embodiment of the invention.
• The FIGS. 3A to 3C show the steps of opening a switchgear according to one embodiment of the invention.
• The figure 4 schematizes the wear curve of the contacts in the presence of arcing contacts.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

With reference to the Figure 1A a circuit breaker 10 with high intensities, greater than 800 A, comprises, for each pole and in a conventional manner, a pair of breaking or main contacts. Each main contact is preferably associated with a pellet 12, 14 of suitable material, for example of silver alloy, and one of the pads 14 is mounted on an arm 16 pivoting between an open position in which it is remote from the fixed contact 12 , and a closing position in which the mechanical and electrical contact between the pads 12, 14 is established. The pole also includes an arc extinguishing chamber 18 and a pair of main terminals (not shown) intended to engage on connection pads. For these high ranges, the circuit breaker 10 comprises a plurality of poles arranged in parallel planes, perpendicular to a pole shaft 20 which is common to them: the order of closure or opening of the poles is transmitted to each movable contact 14 since the pole shaft 20 via a drive mechanism 22 lever.

The pole shaft 20 is rotatably mounted on the casing of the circuit breaker 10 and actuated by appropriate means. In particular, for open circuit breakers with intermediate pole shaft and high electrodynamic resistance, the actuating mechanism is of the toggle type, with two links 24, 26 pivoting relative to each other. One of the rods 24 is articulated in rotation on a trigger hook 28 pivotally mounted on a fixed axis; the other rod 26 is mechanically coupled to a crank 30 of the pole shaft 20, which is also common to all the poles and which also forms one of the levers of the drive mechanism 22 of the contacts 14.

An opening spring 32 is anchored between the crank 30 and a fixed retainer, and tends to bias the crank 30 toward its open position. An opening pawl 34, formed by a lever pivoting about a fixed axis, is controlled by an opening latch 36 in the form of a half-moon; the opening pawl 34 is biased by a spring towards the trigger hook 28, away from the half moon 36. A roller is provided on the opening pawl 34 between its ends to cooperate with a shaped recess of V of the trigger hook 28, which is biased by a spring (not illustrated) tending to shorten the distance between the hinge axis of the toggle mechanism 24, 26 on the trigger hook 28 and the hinge axis of the knee mechanism on the crank 30.

In a preferred embodiment, the switching device 10 is adapted to be reset, that is to say that it is provided with an energy accumulator so as to assist the closing function, such as by example described in the document EP 0 222 645 . In particular, a driving lever 40 is pivotally mounted about a fixed axis 42, and an elastic energy storage device comprising at least one closing spring 44 is pivotally mounted on a fixed point and a finger of the driving lever 40. The driving lever 40 carries a roller 46 intended to cooperate with a camming cam 48 keyed on a shaft 50 and having a roller 52 adapted to cooperate with a locking pawl 54 pivoting about a fixed axis. A locking latch 56, able to lock the pawl 54, is biased resiliently by a spring towards its closed position; the pawl 54 is itself biased by a spring towards its locked position.

The pole shaft 20 is actuated via these various elements and then drives the movable contacts 14. For this purpose, its crank 30 is provided, for each pole, with a connecting rod 60 which connects it to the arm The support arm 16 is provided with two sliding parts relative to one another: a cage 62 is moved directly by the rod 60 relative to which it is pivotally mounted. The portion 64 of the arm 16 which carries the contact pad 14 slides inside the cage 62, preferably hinged about an axis 66; spring means 67, for example one or more contact pressure springs, arranged between the support 64 and the cage 62 urge the pellet 14 in projecting position relative to the cage. This configuration allows an over-closing stroke of the contact pad 14 relative to the docking, so that in current passage position between the contacts 12, 14, the cage 62 can continue its movement without increasing the pressure on the pellets 12, 14. The arm 16 is thus pivotally mounted by its cage 62 about a first axis 68 between the closed position and the open position, and the support 64 of the movable contact 14 is articulated on a second axis 66 of the cage 62.

When closing the contacts 12, 14, in a first step, the pole shaft 20 is rotated, and the toggle mechanism directly drives the contact arm 16; when closing, the two pellets 12, 14 come into contact ( Figure 1B ). The shaft 20 can then continue its course, and the movement of the cage 62 of the arm 16 continues beyond the docking position, the movable contact 14 "sinking" inside the cage 62: figure 1C . In particular, in the preferred embodiment, the opening distance d ₁ is of the order of 40 mm, and the depression d ₂ can be of the order of 4.5 to 6 mm, for example 5, 5 mm, the stroke of the cage 62 is thus more than 10% greater than the opening distance.

Moreover, in the illustrated embodiment, the toggle system 22 and remote pole shaft 20 allows a reduction of displacements, and the rotational stroke of the pole shaft 20 continues on a significant angle α ₂ after the closing of the poles. In particular, the total travel α of the pole shaft 20, fixed and determined by the design of the apparatus, is of the order of 45 to 50 °. At half rotation of the shaft 20, the movable contact 14 has already traveled ¾ of its stroke, and the opening of the contacts is only 10 mm; thus, during the docking of the contacts 12, 14 and after a stroke α ₁ , it remains to the shaft 20 preferably still about 30% of its rotation to be performed.

According to the invention, this remaining stroke α ₂ is used to accurately determine the depression d ₂ of the contact support 64, that is to say the degree of erosion of the contact pads 12, 14. indeed, as and when they wear, the contacting of the pellets is later and the depression d ₂ starts at a rotation α ₁ upper bar 20; the stroke α ₂ of the pole shaft 20 after docking decreases accordingly, which decreases the driving stroke d ₂ of an amount equal to the variation in the thickness of the pellets 12, 14, that is to say their wear. The angular variation (α ₂ - α ₂ ;) of the residual rotation of the bar 20 after closure is thus directly correlated with the variation (d ₂ - d _2i ) of the driving distance of the fixed contact, and therefore with the wear contacts 12, 14.

According to the invention, a sensor 70 measures the rotation α ₂ of the pole shaft 20 between the moment of contact between mobile and fixed contacts 12, 14, that is to say the beginning of the current flow in the device 10, and the limit of the shaft 20 in the closed position. In fact, the stroke α of the shaft 20 is constant (of the order of about fifty degrees - for example α = 52 °) and the driving distance d _2i of the contacts is set at the beginning of the life of the switching device 10 (for example d _2i = 5.5 mm); a simple measurement, either in the factory or during the first determination which is performed by definition in the absence of wear of the contacts, gives the value of the two stages of travel of the shaft; for example α = 32 ° _1i and α _2i = 20 °. A direct relation makes it possible to evaluate, over time, the distance d ₂ or the wear (d ₂ - d _2i ) as a function of the variation (α ₂ - α _2i ), for example by a percentage.

It should be noted that, in the preferred embodiment, thanks to the decoupling and the large variation of the angular position α ₂ of the pole bar 20 corresponding to the small variation of the crushing stroke d ₂ , typical of open circuit breakers. 10, it is possible to precisely determine the wear of the contacts, determination that it is possible to correlate with a remaining life of the product (see for example WO 2004/057634 ); in particular, a lifetime can be estimated by comparing the wear (d ₂ - d _2i ) with a minimum over-travel allowed before changing the contact pads 12, 14.

Preferably, the sensor 70, of small volume, is located at the end of the bar 20, for example at an end near the housing of the circuit breaker 10, outside the areas likely to be polluted during cuts by debris and away from possible jets hot gases.

The cut-off devices 10 with high electrodynamic resistance have a service life that can reach thirty years; advantageously, the sensor 70 is of the non-contact type in order to limit any bias due to wear or friction within the sensor 70. In particular, a non-contact sliding magnetic type sensor, particularly with a grating (or " Magnetic array type rotation sensor " according to the English terminology), is adapted thanks to its lack of parts likely to degrade quickly. As illustrated in figure 2 this type of sensor 70 comprises magnetic means 72, in particular a magnet, which can be secured to the element whose rotation is to be determined; in particular, the magnet 72 can be directly coupled to the bar of the poles 20 by bonding at its end, or any other mechanical means. The sensor 70 also comprises detection means 74, and in particular a printed circuit board type detector approximately 4 mm in length; the detector 74 is positioned facing the magnetic means 72, for example coupled to the case of the circuit breaker 10, in particular set up in a suitable housing. The detector 74 is connected in a conventional manner to means for processing the information and presenting the results, for example an electronic module already present on the circuit breaker 10 to which a new function is added.

Advantageously, the sensor 70 is as described in the documents EP 1 830 162 or EP 1 921 423 , with an angular resolution of the order of 0.2 to 0.5 °. In particular, an angular resolution of the order of 0.36 ° is equivalent to less than one thousandth of a revolution: in the previous embodiment, this corresponds to a resolution in the recess of less than 0.1 mm. As the pellets 12, 14 are conventionally manufactured to tolerate a wear of 2.5 to 3 mm, the monitoring of the service life by this method is reliable.

The sensor 70 can be put in place on all the new switching devices 10; preferably, the mounting of the sensor 70 is optional, so as to avoid the additional cost of detection for the cutoff devices 10 for a pure security use in which the visual determination of the wear of the contacts 12, 14 in operation of maintenance can be sufficient. It is also possible to adapt this device for measuring the wear of the contacts by angular variation on existing breaking devices 10, by positioning the two respective parts of the sensor 70, for example by fixing a magnet 72 on the bar 20 which is easily accessible when the circuit breaker cover 10 is open, and attachment of the detector 74 to the housing by any appropriate means, bonding type or other ...

In particular, the device and the method according to the invention are also suitable for the preceding cut-off devices 10 further comprising an arc contact: in this configuration, the arc contact is the main touched by the phenomenon of wear. In view of the accuracy of the determination according to the invention, it is possible to check and monitor the integrity of the contact pads 12, 14, for example to generate an alert if an unacceptable wear rating is exceeded.

In particular, the extinguishing chamber 18 of the high intensity cut-off device 10 is limited by an arc guiding horn 78: see figure 1 A . As also presented in the document EP 0 410 902 , to improve the electrical endurance of the cut-off device 10, a pair of arc contacts 82, 84 is added, near a flange 88 of said horn 78. According to a preferred embodiment illustrated in FIG. figure 3 a fixed arc contact 82 is adjacent to one of the main fixed contacts 12, and the movable arcing contact 84 is located on the same arm 16 as the movable main contact 14, in particular at one end of the same support 64 sliding in the cage 62. Depending on the size of the cut-off device 10, only one pair of arcing contacts 82, 84 is present or several, for example six out of ten arms 16 have movable arcing contacts 84.

As illustrated in FIGS. 3A to 3C the pair of arcing contacts 82, 84 is usually open, i.e. the two arcing contacts are separated from each other; when triggering the breaking device 10, a temporary closing of the arcing contacts 82, 84 takes place before separation of the main contacts 12, 14 so that, during the separation of the main contacts 12, 14, there is has no interruption of the current flowing through the arc contacts; when the movement of the pole shaft 20 continues, the arcing contacts 82, 84 open to interrupt the current, with the formation of an electric arc, guided by the flange 88 and the guide horn 78. the arc is located mainly on the arc contacts 82, 84, their material is chosen to improve their resistance, the main contacts 12, 14 remaining in the material most conducive to the nominal passage of the high intensity current.

In this embodiment, as schematized in figure 4 at first, only the arcing contacts 82, 84 wear out, the main contacts 12, 14 substantially keeping their integrity. Once the arcing contacts 82, 84 are worn, there is no longer a transient closure, and the arc begins to alter the fixed contacts 12, 14. The determination method according to the invention Here, by measuring the rotation angle of the rotary axis 20, it is possible to follow the erosion of the main contacts and to plan a replacement as soon as the inflection in their integrity curve.

In fact, the angle is measured after docking the arcing contacts 82, 84, and it is at first erosion of said arcing contacts 82, 84 which is followed; the wear of the pellets 12, 14 is considered in a second step and an alert is generated either as soon as the pellets 12, 14 start to wear, or if an inappropriate wear rating of the main contacts is exceeded 12 , 14. This embodiment makes it possible to be predictive thanks to the visualization of the erosion of the arcing contacts 82, 84, whereas a conventional recess measurement system does not make it possible to follow it and therefore to anticipate the beginning of the wear of the main contacts 12, 14.

Although the invention has been described with reference to contacts 12, 14 of a cut-off device 10 with high electrodynamic resistance in which the opening mechanism involves a large variation of the angular position of the pole bar 20 for a weak variation of the over-stroke crush, it is not limited to other types of cut-off devices, contactors and / or circuit breakers, may be concerned. If the decoupling of the movements by double connecting rod and toggle lever amplifies the angular difference according to whether the contacts are worn or not, depending on the stroke of the contacts and according to the accuracy of the detection device 70, it is possible to apply the device according to the invention other actuating mechanisms comprising a rotating part.

Claims (11)

1. An electrical protection apparatus (10) comprising at least one pole-unit, each pole-unit comprising:

   - a pair of main contacts (12, 14) that are movable with respect to one another between an open position and a closed position;

   - a support arm (16) of a first main contact (14) comprising a first part (64) supporting the first main contact (14) and a second part (62), the two parts sliding with respect to one another so that, in the closed position of the pair of main contacts (12, 14), the second part (62) can take a first abutment position and a second end-of-travel position in which the first part (64) is depressed into the second part (62);

   - a drive mechanism (22) of the support arm (16) comprising a rotary shaft (20) and at least one connecting rod system (60) which couples the latter pivotally to the second part (62) of the support arm (16);

   the electrical protection apparatus (10) being characterized by the presence of a device for determining the integrity of the main contacts (12, 14), said device (70) being suitable for measuring the angle of rotation (α₂) of the rotary shaft (20) between the first abutment position and the second end-of-travel position.
2. The electrical protection apparatus according to claim 1 wherein the support arm (16) further comprises means (67) biasing the first part (64) to a salient position with respect to the second part (62).
3. The electrical protection apparatus according to one of claims 1 or 2 wherein the electrical protection device comprises a plurality of identical pole-units and a pole-shaft (20) common to all the pole-units, the pole-shaft (20) being the rotary shaft of the drive mechanisms (22).
4. The electrical protection apparatus according to claim 3 further comprising a pair of arcing contacts (82, 84) that are movable with respect to one another between an open position and a closed position, a first movable arcing contact (84) being securedly attached to a support arm (16), the pair of arcing contacts (82, 84) being in the open position in the closed position of the main contacts (12, 14) and in the second end-of-travel position of the main contacts (12, 14), and taking the closed position (82, 84) between the two.
5. The electrical protection apparatus according to one of claims 3 or 4 further comprising a resetting device (44).
6. The electrical protection apparatus according to one of claims 3 to 5 further comprising an actuating mechanism of the pole-shaft (20) with two rods (24, 26).
7. The electrical protection apparatus according to claim 6 wherein rotation (α2) of the pole-shaft (20) between the first abutment position and the second end-of-travel position is about 30 % of the rotation (α) of the pole-shaft (20) between the open position of the main contacts (12, 14) and the second end-of-travel position.
8. The electrical protection apparatus according to one of claims 1 to 7 wherein the device for determining (70) comprises a rotation sensor one component whereof is arranged on the rotation shaft (20).
9. The electrical protection apparatus according to claim 8 wherein the rotation sensor (70) comprises magnetic means (72) arranged on the rotation shaft (20) and detection means (74) fitted on the case of the electrical protection apparatus (10), the magnetic means (72) and detection means (74) communicating without contact.
10. A method for manufacturing an electrical protection apparatus (10) equipped with a device for measuring the erosion of its contacts (12, 14), wherein the electrical protection apparatus (10) comprises a rotary pole-shaft (20) driving at least one movable contact (14) between an open position and a closed position of a pair of contacts (12, 14), said movable contact (14) being mounted movable on its support (16) so that in the closed position of the contacts (12, 14), the movable contact (14) can take an abutment position and a depressed position in its support (16), said method for manufacturing comprising fitting of a rotation sensor (70) of the pole-shaft (20) at the level of one end of said pole-shaft (20).
11. The method according to claim 10 wherein fitting of a sensor (70) comprises securing magnetic means (72) onto one end of the pole-shaft (20) and fitting means for detecting (74) their angular position facing the magnetic means (72).

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