EP1573760B1 - Method for determining the remaining service life of a switching device and corresponding assembly - Google Patents

Abstract

Known methods monitor the contact resilience during the displacement of the switching device actuator in order to determine the contact erosion of contact pieces and the remaining service life of the switching device. Two intervals in particular can be recorded during the displacement of the actuator in order to monitor the contact resilience. According to the invention, a separate sensor is provided to record and display the contact erosion and/or the mechanical wear of the switching device by the monitoring of the contact resilience, said sensor detecting at least one event in order to determine the time interval between two such events.

Description

The invention relates to a method for determining the remaining service life of a vacuum switching device, in particular for detecting and displaying wear conditions of the switching device, by monitoring the through-pressure during the movement of the switching device drive, wherein for the pressure monitoring time intervals between two significant events are determined during the drive movement. In addition, the invention also relates to the associated arrangement for carrying out the method.

The remaining service life of a switching device depends on the state of wear during the operational use of the switching device. Under wear condition of vacuum switching devices in the present context, the determination of the burnup of the contacts and / or the wear of the switching device mechanism is understood in particular by vacuum contactors.

In switching devices, the switching contacts or the entire drive mechanism can be worn depending on the type of load. Decisive determinant for the wear of a switching device is the contact force or contact force with which the compression spring presses the contacts in the closed state against each other. The following statements relate to a vacuum contactor and preferred application of the invention for a vacuum switching device.

The compression spring is located between a spring seat and a bolt guide which is fixedly connected to the movable contact. During the closing process, initially spring support, pressure spring with bolt guide and moving contact move together on the fixed contact. After the movable contact has touched the fixed contact, the spring support moves further in the direction of the contacts. The result caused compression of the prestressed compression spring finally causes the necessary contact force. The way the spring rest from the point of closing the contacts to the final position of the spring rest is referred to as a pressure and is crucial for the contact force generated. The pressure and contact force are coupled together via the spring constant of the compression spring. The turn-off occurs in an analogous manner inversely.

• der Abbrand an den Kontakten zu einem vergrößerten Weg des beweglichen Kontaktes führt und damit der Durchdruck bei gleicher Endlage der Federauflage verringert wird und
• durch mechanischen Verschleiß und Abrieb innerhalb des Schaltgerätes die Endlage der Federauflage von den Schaltkontakten wegwandert und damit ebenfalls der Durchdruck verringert wird.

The contact pressure as well as contact force diminish over the life of a switching device, because

• the burnup at the contacts leads to an enlarged path of the movable contact and thus the pressure is reduced at the same end position of the spring support and
• due to mechanical wear and abrasion within the switching device, the end position of the spring support migrates away from the switching contacts and thus also the through-pressure is reduced.

Decreases the pressure or the contact force of a switching device in the course of life, so from certain values Kontaktverschweißungen and switching failure occur, which can cause serious damage to the system.

In particular, for air contactors, a method for residual life detection of the contact erosion is already known in which the burnup by measuring the time interval between armature opening, which is characterized by a characteristic peak in the coil voltage, and contact opening, which is characterized by the occurrence of a switching path voltage, the burning of the Contact pieces detected and thus the remaining life is determined.

The method for detecting the change in pressure as a substitute criterion for the contact erosion is with the EP 0 694 937B1 put under protection. Specific methods for use with switching devices are described in detail in the EP 0 878 016 B1 , of the EP 0 878 015 B1 and the EP 1 002 325 B1 described. It is consistently based on the fact that the change in pressure especially during the turn-off, ie the opening of the switch contacts are detected by an electromagnetic drive, which specifically determines the burnup of the switch contacts and from the remaining life of the switching device is calculated.

Furthermore, from the DE 100 28 559 an electromagnetic switching device, in particular contactor, known with a load contact of fixed contact pieces and a movable contact bridge having contact pads with an initial contact pad thickness when new, wherein the contact pads are burned after a number n of switching cycles under rated load, the contact bridge of a contact bridge carrier , which detects the contact bridge in a driving range, can be lifted from the fixed contact pieces, wherein the contact bridge carrier at least in the driving range of such a wear-resistant material that the contact bridge carrier in the driving range after the number n of switching cycles under rated load Maximalabtrag of a maximum of 10% of the initial Contact pad thickness. This method is used to monitor aerial switching devices with bridge contacts.

In the case of vacuum contactors in particular, contact erosion has hitherto been measured by the fact that a bar mark is attached to the bolt guide of the vacuum tube, which is an indicator of the burn-off of the contacts in the tube. Both methods capture only the contact erosion. The wear of the switching mechanism can thus not be detected

The object of the invention is therefore to provide a method which can determine both the wear of a vacuum switching device as a result of erosion of the contacts and the mechanical wear within the switching device mechanism, so that appropriate maintenance measures can be carried out in a timely manner. These maintenance works can be especially useful in renewal of main contacts as well as replacement wear-prone components until replacement of the entire switching device.

The object is achieved by the sequence of measures of claim 1. Further developments are specified in the dependent method claims. An associated arrangement is the subject of the claim 12. Further developments of the arrangements are the subject of the dependent claims.

With the invention, it is now possible in particular to determine the entire state of wear of the vacuum switching device. In this case, the contact wear is not only detected as in the prior art, but also wear conditions of the moving components of the switching device are taken into account. This is particularly important in vacuum contactors, because there on the one hand, the contact stroke is comparatively low, but on the other side of the drive for the switching contact movement via a lever mechanism with power deflection and amplification and thereby at high numbers of switching to the moving mechanical Components can lead to a non-negligible wear.

In a particularly advantageous embodiment of the invention, it is also possible to discriminate between the actual contact erosion and the wear of the drive mechanism. This can be achieved in particular for the practice by proper maintenance of the vacuum switching devices considerable savings.

Figur 1

eine schematische Darstellung eines Vakuumschützes mit zugehörigem Antrieb einschließlich der schaltmechanischen Komponenten,

Figur 2

eine Durchdruckmessung mit einer festen Tauchspule und beweglichem Dauermagneten,

Figur 3

eine Anordnung zur Messung des Bewegungsbeginnes mit einem Piezobiegewandler,

Figur 4

eine Messanordnung mit einer Lichtschranke an der Federauflage,

Figur 5

eine mechanische Messung mit einem Schalter und

Figur 6

eine bewegliche Messung mit einer Lichtschranke an der Bolzenführung.

Further details and advantages of the invention will become apparent from the following description of the figures of examples with reference to the drawing in conjunction with the claims. They each show the example of a vacuum switch

FIG. 1

a schematic representation of a vacuum contactor with associated drive including the switching mechanical components,

FIG. 2

a Durchdruckmessung with a fixed plunger coil and movable permanent magnet,

FIG. 3

an arrangement for measuring the start of movement with a piezo bending transducer,

FIG. 4

a measuring arrangement with a light barrier on the spring support,

FIG. 5

a mechanical measurement with a switch and

FIG. 6

a movable measurement with a light barrier on the bolt guide.

All figures described below relate specifically to vacuum contactors. Vacuum contactors have recently proven to be an alternative to air guns. This advantageously up to some 10 ^{6 operations are} possible, so that such contactors are suitable for use in many fields of technology.

FIG. 1 shows a typical structure of a vacuum contactor with associated drive. The pressure-generating components / assemblies are: The lever, the spring support and the movable tubular bolt with the attachments such as current band connection, lever support, switch position indicator and the associated mounting hardware. Abrasion or plastic deformation can occur at the locations marked with letters A to G, which can either increase the pressure or reduce the pressure.

Hereinafter, the structure of a vacuum contactor with associated electromagnetic drive and associated contactor mechanism will be described, which serves to switch a single or multi-pole network. It is considered only one phase of a three-phase network with a single vacuum interrupter.

According to FIG. 1 the latter part of a vacuum contactor 1 comprises a vacuum interrupter 10, the contactor mechanism 20, 30, 40 and the drive 100. Specifically, a vacuum interrupter 10 is attached to an abutment 3 with boom 4. The boom 4 carries the vacuum interrupter 10, to which a fixed contact pin 15 of the interrupter 10 is clamped in the boom 4.

The vacuum interrupter 10 consists of hollow cylindrical components 11 to 13, wherein the hollow cylinder 11 and 13 are arranged axially displaceable against each other by a linearly resilient metal bellows 12. The components 11 and 13 are electrically insulated from one another, for which purpose one of the components can be made, for example, of ceramic material.

In the vacuum interrupter 10 are under vacuum two switch contacts 17 and 18 axially movable against each other, wherein the switching contact 17 is connected as a fixed contact with the fixed bolt 15 and the switch contact 18 is connected as moving contact with a movable pin 16 in the axial direction.

The switch contacts 17 and 18 of the vacuum interrupter 10 are actuated by means of the electromagnetic drive 100, to which a structure of magnetic yoke 101, armature 102 and associated coils 105, 105 'for electromagnetic excitation is present. The magnetic yoke 101 is mounted in a holder 110. The magnet armature 102 has a recess 103 with attachment 105 for a contact carrier 30.

By the electromagnetic drive 100, the armature 102 can be brought into two vertically different positions, of which the lower correspond to the "closed" position of the vacuum contactor 10 and the upper of the "open" position of the vacuum contactor 10. This must be in FIG. 1 the vertical displacement are converted into a horizontal displacement, for which a deflection device 20 is present.

In detail is in the FIG. 1 the Bewegkontaktbolzen 16 outside the interrupter 10 is supported against the pressure of a spring 21, wherein the spring 21 is supported on a spring support 22. There is an L-shaped lever 25 is provided which is mounted with an axis 26 in the break point. The short lever arm of the reversing lever 25 presses with a first end member 27 on the spring support 22, while the long lever arm with a second end member 28 in a recess 31 of the contact carrier 30, which - as already mentioned - is connected to the armature 102 of the magnetic drive 100, is guided. There is a support plate 35 for the contact carrier 30 is present.

With the L-shaped deflection lever 25 can be a relatively large displacement in the vertical direction in a smaller displacement in the horizontal direction with appropriate application of force implement. This is necessary for the operation of the vacuum contactor 10, in which in particular a sufficient contact pressure between the contact surfaces of the switching contacts 17 and 18 must be generated. For this purpose, the spring 21 is clamped for the closed position by means of a predeterminable pressure and generates a contact force sufficient for the closed position of the switching contacts 17, 18. The pressure is in the FIG. 1 thereby makes clear that when the switching position of the end element 27 is open at the short lever arm of the reversing lever 25 this is supported by a rear lever support 23.

In the FIG. 1 As mechanical moving parts of the display 40, there are further provided a switch position indicator 41, a current band terminal 42, and a current band 44 connected to the rail terminal 45.

When in the FIG. 1 In general, the switching path of the contact arrangement shown is comparatively small, for example <2 mm. It follows that the play of the individual movements occurring in the switching device drive with the associated deflection during frequent activation can not be neglected. In the design of switching devices with such drive and power transmission facilities, these conditions must be considered.

The service life of a switching device is influenced by the wear of all mechanically moving parts. This wear is in a known manner on the one hand by the burnup causes the electrical switching contacts on the contact surfaces A, since the thickness of the contact pieces reduced as a result of burnup.

From the FIG. 1 However, it also follows that on the other hand, the mechanical wear of the movable drive components can also have an influence on the life of the entire switching device. Such wear is particularly Abriebe at camps or even plastic deformations that can affect either by increasing the pressure or reducing the pressure individually. Ideally, such influences compensate each other at the various points of the switching device mechanism.

In detail are in the FIG. 1 In addition to the contact surfaces continue the points B to H, where wear can occur registered. B is the support of the end element 27 on the spring support 22, C its support on the rear lever support 24, E the mechanical stress of the other end element 28 in the cam groove 31 of the contact carrier 30, F the contact support in the armature, G / G ' the support of magnetic armature 102 on the magnetic yoke 101 at the pole faces and H / H 'the holder 110 of the magnetic drive 100 in a base plate.

In the FIGS. 2 to 6 is in a simplified representation of the switch contacts 17, 18 each of the fixed contact 18 with the housing wall 11 fixedly connected. The moving contact 18 is located on a bolt 16 which is movable via a bellows 13 or the like in the axial direction of the arrangement. In this case, a contact force for closing the moving contact 18 is generated via a contact pressure spring 21. The contact pressure spring 21 is located between abutment 22 and 24, wherein the outer thrust bearing 22 corresponding to the drive FIG. 1 communicates.

In a known manner, a sufficient pressure of the spring is decisive for ensuring the switching contact. With longer life, the pressure changes due to the contact erosion, so that the pressure detection can be used in a known manner as a substitute criterion for the erosion of the contacts. Since the drive movement in vacuum contactors has deflections with corresponding deflection pumps, which are likewise subject to mechanical wear, the through-pressure is also dependent on the mechanical wear of the drive components, especially in the case of vacuum switching devices. Both influencing factors are now recorded.

Since already in the prior art, the through pressure measurement is carried out in detail by a time measurement and in particular the time interval between the armature movement start and contact opening is determined, a time measurement is subsequently also performed. For this timestamps must be set in a suitable manner.

For the latter purpose, alternative examples according to the FIGS. 2 to 6 described.

The five alternatives for determining the wear and the residual life of a switching device are each based on a time interval measurement between two events during the turn-off, using sensors for continuous signal detection. This procedure is based on the knowledge that the movement sequence of the mechanical components involved in particular does not depend on the time of the switch-off command or, for example, the coil voltage depends on an electromagnetically actuated switching device. There are different sensors possible.

As a first example, a fixed plunger coil 125 with movable permanent magnet 126 is described on the spring support 22 for a 1 or 3-pole measurement: There is a time interval .DELTA.t between the beginning of the movement of the spring support 22 until the time of contact opening. The beginning of movement of the spring support 22 induced by the movement of the permanent magnet 126, a voltage pulse in the plunger coil 125. The so determined time interval .DELTA.t corresponds to the known pressure profile of the spring support 22 the through-pressure and thus is a measure of the total wear consisting of contact erosion and mechanical wear of the drive components ,

The measurement can be carried out on only one current path (1-pole) of the switching device as well as on all 3 current paths (3-pole) of a three-phase switching device. In the latter case, the signals of the three voice coils can be advantageously combined by connecting all three voice coils in series, in which case only the sum signal is evaluated.

• Es liegt eine galvanische Trennung zu spannungsführenden Teilen vor.
• Es gibt keine mechanische Verbindung zwischen beweglicher Federauflage und der Tauchspule, so dass die Messung verschleißfrei erfolgt.
• Die Endlage der Federauflage kann in weiten Grenzen variieren, so dass keine Justage erforderlich ist.
• Ein während der Lebensdauer des Schaltgerätes veränderter Offset führt zu keiner Funktionsbeeinträchtigung.

There are the following advantages:

• There is a galvanic isolation to live parts.
• There is no mechanical connection between the movable spring support and the plunger so that the measurement is wear-free.
• The end position of the spring seat can vary within wide limits, so that no adjustment is required.
• A changed during the life of the switching device offset leads to no functional impairment.

As a second example, a detection of the start of movement with a piezo bending transducer 137 on the spring support 22 for a 1- or 3-pole measurement is described: There is a time interval .DELTA.t between the beginning of the movement of the spring support 22 until the time of contact opening. The start of movement of the spring support causes in the piezo bending transducer 137 a charge separation and thus a voltage at the electrodes of the piezoelectric transducer 137. Depending on the load resistance, this voltage can be up to several hundred volts. The specific time interval corresponds to reproducible Speed profile of the spring seat 22 the through-pressure and is thus a measure of the total wear - consisting of burnup and mechanical wear. The measurement can be carried out on only one current path (1-pole) of the switching device as well as on all 3 current paths (3-pole) of a three-phase switching device.

• Es entsteht ein großer Signalpegel.
• Die Anordnung ist platzsparend.
• Es ist nur eine Grobjustage erforderlich.
• Während der Lebensdauer des Schaltgerätes veränderter Offset führt zu keiner Funktionsbeeinträchtigung.

There are the following advantages:

• It creates a large signal level.
• The arrangement saves space.
• Only a rough adjustment is required.
• During the lifetime of the switching device changed offset leads to no functional impairment.

As a third example 3, a photoelectric sensor 141 is attached to the spring support 22: There is a time interval .DELTA.t between the beginning of the movement of the spring support to the time of contact opening. The start of movement of the spring support 22 causes an interruption or release of the light beam in the light barrier 141. This change in state is used to detect the start of movement of the time measurement. For this purpose, a transmitting and receiving diode on one side or both sides - 1 or more poles - arranged in the direction of movement of the spring support 22 and the bolt guide. An interruption or release of the light beam takes place according to FIG. 3 through a window 141 as openings, grid structures, elevations and or depressions, which are integrated either in the spring seat 22, fixedly connected to the spring seat 22 or provided with an adjustment device. The time interval .DELTA.t determined in this way corresponds-with a reproducible speed profile of the spring support-to the through-pressure and is thus a measure of the total wear of the switching device, consisting of burnup and mechanical wear. The measurement can be carried out both on a current path (1-pole) of the switching device as well as on all current paths of a three-phase switching device.

• Es liegt eine galvanische Trennung zu den spannungsführenden Teilen vor.
• Es existiert keine mechanische Verbindung zwischen der beweglichen Federauflage und der Lichtschranke, so dass verschleißfrei gemessen wird.
• Es entsteht ein großer Signalpegel.

There are the following advantages:

• There is a galvanic isolation to the live parts.
• There is no mechanical connection between the movable spring support and the light barrier, so that it is measured without wear.
• It creates a large signal level.

In a fourth example, a mechanical measurement takes place by means of a switch S on the spring support 22:
There is a time interval .DELTA.t between the beginning of the movement of the spring support to the time of contact opening. The start of movement of the spring support 22 causes an interruption according to the in FIG. 5 shown normally open or release of the switch contact S (normally closed). This change of state is used to detect the start of movement of the time measurement. The switching element can be controlled depending on the expression as NC or NO directly by the spring element 21 or a collection or depression or a fixedly connected additional element with or without adjustment device. The switching element can be mounted on one or on all current paths.

The thus determined time interval .DELTA.t corresponds to reproducible speed profile of the spring support the through pressure and is thus a measure of the total wear consisting of burnup and mechanical wear. The measurement can be carried out both on a current path (1-pole) of the switching device as well as on all current paths of a three-phase switching device.

• Es liegt eine galvanische Trennung zu den spannungsführenden Teilen vor.
• Es existiert keine mechanische Verbindung zwischen der beweglichen Federauflage und der Lichtschranke, so dass verschleißfrei gemessen wird.
• Es entsteht ein großer Signalpegel.

There are the following advantages:

• There is a galvanic isolation to the live parts.
• There is no mechanical connection between the movable spring support and the light barrier, so that it is measured without wear.
• It creates a large signal level.

The fifth example of the sensor detection is a light barrier on the pin guide with 1- or 3-pole measurement: In contrast to the methods according to the FIGS. 2 to 5 With the light barrier, a measurement .DELTA.t is taken directly from the contact opening to a waypoint (WP) of the bolt guide, which is already a measure of the burnup. In this respect, in this measurement, the through-pressure is only utilized indirectly via the support of the end element 27 of the reversing lever 25.

The latter method is particularly applicable when the contact movement has a constant speed. The mechanical wear of the switching device is detected by the number of contacts. The need for maintenance is then indicated either by the contact erosion or the number of operations. Signaling at the waypoint (WP) is carried out by optocouplers, magnet + reed contact or magnet + Hall sensor etc ..

Especially in the last example, the following advantages result: There is no change to the previous design of vacuum tube, bolt guide, spring and contact plate required. Only the previous tab with line marking is to be replaced. The remaining elements such as e.g. The opto-coupler and associated electronics can be accommodated in the contactor cover. The signal can then be processed so that it can be fed directly into the existing electronics. Since the procedure is fundamentally different, the software must be adapted accordingly minimal and without additional extension.

On the basis of the individual examples, the application for vacuum switching devices, in particular for vacuum contactors, has been described in particular. Quite correspondingly, however, this principle with the separate time sensor is also applicable for air gunners. There, compared to the state of the art presented at the outset, there is now also the possibility to record and evaluate the mechanical wear of the switchgear mechanics.

When switching operation of switching devices, in particular of contactors and circuit breakers, wear occurs, which affects the reliability of the switching device from a certain size. It is therefore desirable to monitor the wear of the switching device in order to make timely and at appropriate times the necessary maintenance on the switching devices can. Wear factors include contact wear due to burnup and abrasion, as well as wear on components of the switching device drive due to abrasion and deformation. The latter wear leads e.g. In addition, the mechanical play in the switchgear drive increases to possibly impermissible values.

• Kontaktabbrand
• Kontaktfeder-Durchdruck
• vom mechanischen Spiel herrührender Durchdruckverlust

kontinuierlich während des Schaltgerätebetriebs bestimmt werden und bei Überschreiten vorgegebener Grenzen Wartungshinweise ausgegeben werden.With the method, the wear sizes

• contact erosion
• Contact Feather Pressing
• from mechanical play resulting pressure loss

be determined continuously during the switchgear operation and maintenance instructions are issued when predetermined limits are exceeded.

The detection of the wear sizes is expediently carried out during the switch-off process of the switching device and will be described below. For additional detection or specification of other motion variables, such as closing speed, acceleration, positions or the like, the method can also be extended to the switch-on of the switching device.

In the following, a sensor-based detection of the contact pressure of the contact force spring and the discrimination of the variables of the contact wear and the mechanical wear which change the through-pressure are described on the basis of a model calculation:

The essential forces that are used in the opening operation for the opening movement of the contacts and the components of the switching device drive coupled thereto are in normal operation, i. without short-circuit breaking, the contact spring forces and the drive spring force. While the drive spring force acts over the entire opening movement of the switching mechanism, the contact spring forces are effective only as long as the contact pressure of the contact force spring has not decreased to zero during the opening movement.

During the switch-off process, these spring forces lead to an accelerated lifting and / or rotating movement, so that certain positions of the movable components of the switchgear mechanism can be determined at certain times characteristic of the opening process. Therefore, in the new state of the switching device, position values are obtained which increasingly differ from the values of the state of use with increasing service life and cumulative contact erosion as well as mechanical wear.

In the following, the movement sequence of the moving components is treated as a linear movement and can be subdivided into two consecutive sections during the switch-off process:

First movement section:

Beschleunigung:

$${\mathrm{b}}_{\mathrm{1}}\left(\mathrm{t}\right)\mathrm{=}\left({\mathrm{K}}_{\mathrm{Kontakt}}\mathrm{+}{\mathrm{K}}_{\mathrm{Antrieb}}\right)\mathrm{/}\mathrm{m}$$

Geschwindigkeit:

$${\mathrm{v}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{=}{\mathrm{t}}_{\mathrm{D}}\mathrm{*}\left({\mathrm{K}}_{\mathrm{Kontakt}}\mathrm{+}{\mathrm{K}}_{\mathrm{Antrieb}}\right)\mathrm{/}\mathrm{m}$$

Weg:

$${\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{=}{}^1{/}_2*{{\mathrm{t}}_{\mathrm{D}}}^2\mathrm{*}\left({\mathrm{K}}_{\mathrm{Kontakt}}\mathrm{+}{\mathrm{K}}_{\mathrm{Antrieb}}\right)\mathrm{/}\mathrm{m}$$

Start t = 0, velocity v (t = 0) = 0, end t = t _D at the time the pressure has decreased to zero.
The following applies:

Acceleration:

$${\mathrm{b}}_{\mathrm{1}}\left(\mathrm{t}\right)\mathrm{=}\left({\mathrm{K}}_{\mathrm{Contact}}\mathrm{+}{\mathrm{K}}_{\mathrm{drive}}\right)\mathrm{/}\mathrm{m}$$

Speed:

$${\mathrm{v}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{=}{\mathrm{t}}_{\mathrm{D}}\mathrm{*}\left({\mathrm{K}}_{\mathrm{Contact}}\mathrm{+}{\mathrm{K}}_{\mathrm{drive}}\right)\mathrm{/}\mathrm{m}$$

Path:

$${\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{=}{}^1{/}_2*{{\mathrm{t}}_{\mathrm{D}}}^2\mathrm{*}\left({\mathrm{K}}_{\mathrm{Contact}}\mathrm{+}{\mathrm{K}}_{\mathrm{drive}}\right)\mathrm{/}\mathrm{m}$$

Second movement section:

Beschleunigung:

$${\mathrm{b}}_{\mathrm{2}}\left(\mathrm{t}\right)\mathrm{=}{\mathrm{K}}_{\mathrm{Antrieb}}\mathrm{/}\mathrm{m}$$

Geschwindigkeit:

$${\mathrm{v}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\mathrm{=}{\mathrm{v}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{+}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\mathrm{-}{\mathrm{t}}_{\mathrm{D}}\right)\mathrm{*}{\mathrm{K}}_{\mathrm{Antrieb}}\mathrm{/}\mathrm{m}$$

Weg:

$${\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\mathrm{=}{\mathrm{v}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)*\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\mathrm{-}{\mathrm{t}}_{\mathrm{D}}\right)+{}^1{/}_2*{\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\mathrm{-}{\mathrm{t}}_{\mathrm{D}}\right)}^2*{\mathrm{K}}_{\mathrm{Antrieb}}\mathrm{/}\mathrm{m}$$

Start t = t _D , end t = t _Ö at the time when the contact opening takes place. The following applies:

Acceleration:

$${\mathrm{b}}_{\mathrm{2}}\left(\mathrm{t}\right)\mathrm{=}{\mathrm{K}}_{\mathrm{drive}}\mathrm{/}\mathrm{m}$$

Speed:

$${\mathrm{v}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\mathrm{=}{\mathrm{v}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{+}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\mathrm{-}{\mathrm{t}}_{\mathrm{D}}\right)\mathrm{*}{\mathrm{K}}_{\mathrm{drive}}\mathrm{/}\mathrm{m}$$

Path:

$${\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\mathrm{=}{\mathrm{v}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)*\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\mathrm{-}{\mathrm{t}}_{\mathrm{D}}\right)+{}^1{/}_2*{\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\mathrm{-}{\mathrm{t}}_{\mathrm{D}}\right)}^2*{\mathrm{K}}_{\mathrm{drive}}\mathrm{/}\mathrm{m}$$

The time signals entering the movement are the armature movement start t = 0, the time t _D when the negative pressure has dropped to zero and the contact opening time t _Ö when the movable contacts are lifted off the fixed contacts by the switching device drive.

The times t = 0 and t _ö can be obtained in the prior art from electrical voltage signals on the magnetic drive and the switch contacts. The time t _D , which indicates the zero-pressure value during the switch-off process, is inventively detected by a sensor on the components of the switchgear drive generating through-pressure.

The resulting in the first movement section path s ₁ (t _D ) is directly or except for a proportionality constant identical to the through-pressure (= spring travel) by which decreases the spring length during the switch-on.

When new, s ₁ (t _D ) has a _new value, with the new condition of the contacts. ie the thickness of the contact pads, and with the mechanical wear, ie wear path, = zero corresponds.

Through contact erosion and mechanical wear, a current value s ₁ (t _D ) results during the device service life, from which a cumulative value of contact erosion (d _burnup ) and mechanical wear (d _mechanism ) can be determined. The following applies: $${\mathrm{d}}_{\mathrm{combustion}}\mathrm{+}{\mathrm{d}}_{\mathrm{mechanics}}\mathrm{=}{\mathrm{s}}_{\mathrm{1}}{\left({\mathrm{t}}_{\mathrm{D}}\right)}_{\mathrm{New}}\mathrm{-}{\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)$$

From the second movement section is obtained for the new condition of the switching device, the structurally given, mechanical game s ₂ (t _Ö ) _new .

bestimmt werden kann.Due to mechanical wear d _mechanics , this mechanical game increases, resulting $${\mathrm{d}}_{\mathrm{mechanics}}\mathrm{=}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\mathrm{-}{\mathrm{s}}_{\mathrm{2}}{\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)}_{\mathrm{New}}$$

can be determined.

kann der aktuelle Kontaktabbrand separiert werden. Es gilt: $${\mathrm{d}}_{\mathrm{Abbrand}}\mathrm{=}{\left({\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\right)}_{\mathrm{neu}}\mathrm{-}\left({\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\right)$$

From the values updated during the switchgear service life $${\mathrm{d}}_{\mathrm{combustion}}\mathrm{+}{\mathrm{d}}_{\mathrm{mechanics}}\mathrm{and}{\mathrm{d}}_{\mathrm{mechanics}}$$

the current contact erosion can be separated. The following applies: $${\mathrm{d}}_{\mathrm{combustion}}\mathrm{=}{\left({\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\right)}_{\mathrm{New}}\mathrm{-}\left({\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\right)$$

The functional reliability of the switching device can now be controlled with these burnup and wear values so that within the switching device service life the values d _burnup and throughpressure s ₁ (t _D ) of the contact force spring do not exceed or fall short of predetermined limits. In addition, the effective for the through-pressure mechanical wear can be specified and a limit can be specified, upon reaching the switching device mechanism can be assessed as consumed.

$$\mathrm{=}\left[\mathrm{1}\mathrm{-}{\left({\mathrm{t}}_{\mathrm{D}}\mathrm{/}{\mathrm{t}}_{\mathrm{D}\mathrm{,}\mathrm{neu}}\right)}^{\mathrm{2}}\right]\mathrm{*}\mathrm{100}$$

$$\mathrm{Abbrand}\left[\mathrm{\%}\right]\mathrm{=}\left[{\left({\mathrm{s}}_{\mathrm{1}}\mathrm{\left(}{\mathrm{t}}_{\mathrm{D}}\mathrm{\right)}\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\right)}_{\mathrm{neu}}\mathrm{-}\mathrm{\left(}{\mathrm{s}}_{\mathrm{1}}\mathrm{\left(}{\mathrm{t}}_{\mathrm{D}}\mathrm{\right)}\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\mathrm{\right)}\right]\mathrm{/}\left[{\left({\mathrm{s}}_{\mathrm{1}}\mathrm{\left(}{\mathrm{t}}_{\mathrm{D}}\mathrm{\right)}\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{o}}}\right)\right)}_{\mathrm{neu}}\right]\mathrm{*}\mathrm{100}$$

$$\mathrm{=}\mathrm{1}\left[\mathrm{1}\mathrm{-}\mathrm{(}{{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\ddot{\mathrm{o}}}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\mathrm{)}\mathrm{/}{\left({{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\ddot{\mathrm{o}}}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\right)}_{\mathrm{neu}}\right]\mathrm{*}\mathrm{100}$$

For this purpose, it is expedient to obtain the relevant functional, erosion and wear variables in terms of percentage sizes: $$\mathrm{contact\; spring}\mathrm{-}\mathrm{Pressing}\left[\mathrm{\%}\right]\mathrm{=}\left[\mathrm{(}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0001.png"\; state="\{\{state\}\}">s</figure-callout>}}_{\mathrm{1}}{\left({\mathrm{t}}_{\mathrm{D}}\right)}_{\mathrm{New}}\mathrm{-}{\mathrm{s}}_{\mathrm{1}}\left({\mathrm{t}}_{\mathrm{D}}\right)\mathrm{)}\mathrm{/}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0001.png"\; state="\{\{state\}\}">s</figure-callout>}}_{\mathrm{1}}{\left({\mathrm{t}}_{\mathrm{D}}\right)}_{\mathrm{New}}\right]\mathrm{*}\mathrm{100}$$

$$\mathrm{=}\left[\mathrm{1}\mathrm{-}{\left({\mathrm{t}}_{\mathrm{D}}\mathrm{/}{\mathrm{t}}_{\mathrm{D}\mathrm{.}\mathrm{New}}\right)}^{\mathrm{2}}\right]\mathrm{*}\mathrm{100}$$

$$\mathrm{combustion}\left[\mathrm{\%}\right]\mathrm{=}\left[{\left({\mathrm{s}}_{\mathrm{1}}\mathrm{\left(}{\mathrm{t}}_{\mathrm{D}}\mathrm{\right)}\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\right)}_{\mathrm{New}}\mathrm{-}\mathrm{\left(}{\mathrm{s}}_{\mathrm{1}}\mathrm{\left(}{\mathrm{t}}_{\mathrm{D}}\mathrm{\right)}\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\mathrm{\right)}\right]\mathrm{/}\left[{\left({\mathrm{s}}_{\mathrm{1}}\mathrm{\left(}{\mathrm{t}}_{\mathrm{D}}\mathrm{\right)}\mathrm{+}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\right)}_{\mathrm{New}}\right]\mathrm{*}\mathrm{100}$$

$$\mathrm{=}\mathrm{1}\left[\mathrm{1}\mathrm{-}\mathrm{(}{{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\ddot{\mathrm{O}}}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\mathrm{)}\mathrm{/}{\left({{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\ddot{\mathrm{O}}}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\right)}_{\mathrm{New}}\right]\mathrm{*}\mathrm{100}$$

With negligible mechanical play in new condition, t _Ö ≈ t _D and you get: $$\mathrm{combustion}\left[\mathrm{\%}\right]\mathrm{=}\left[\mathrm{1}\mathrm{-}\mathrm{2}\mathrm{*}\left({{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\ddot{\mathrm{O}}}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\right)\mathrm{/}{{{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}}_{\mathrm{New}}\right]\mathrm{*}\mathrm{100}$$

The resulting from the mechanical wear relative proportion of the reduction in pressure of the contact force spring is given by the expression $${\mathrm{d}}_{\mathrm{Mechanic}}\mathrm{/}{\mathrm{Pressing}}_{\mathrm{New}}\mathrm{=}\left({\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\mathrm{-}{\mathrm{s}}_{\mathrm{2}}{\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)}_{\mathrm{New}}\right)\mathrm{/}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0001.png"\; state="\{\{state\}\}">s</figure-callout>}}_{\mathrm{1}}{\left({\mathrm{t}}_{\mathrm{D}}\right)}_{\mathrm{New}}$$

Thus, a percentage of the mechanical wear related to the through-pressure can now be specified. The following applies: $$\mathrm{mechanical\; wear}\left[\mathrm{\%}\right]\mathrm{=}\left[\left({\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)\mathrm{-}{\mathrm{s}}_{\mathrm{2}}{\left({\mathrm{t}}_{\ddot{\mathrm{O}}}\right)}_{\mathrm{New}}\right)\mathrm{/}{\mathrm{<figure-callout\; id="1"\; label="s"\; filenames="imgf0001.png"\; state="\{\{state\}\}">s</figure-callout>}}_{\mathrm{1}}{\left({\mathrm{t}}_{\mathrm{D}}\right)}_{\mathrm{New}}\right]\mathrm{*}\mathrm{100}$$

ein.In addition to the time values t _D , t _ö in the new and used state, the quotient also goes into this quantity $${\mathrm{K}}_{\mathrm{drive}}/\left({\mathrm{K}}_{\mathrm{Contact}}\mathrm{+}{\mathrm{K}}_{\mathrm{drive}}\right)$$

one.

Finally, to define the end of service life, the functional, burnup and wear variables are related to percentage limit values which ensure safe operation of the switching device. Thus, a distinction can be made between the actual contact erosion and the mechanical wear. This is particularly important in vacuum contactors, since contact burnout usually the entire tube is replaced.

In the case of the method for determining changes in through-pressure, which is illustrated by means of the individual examples, the dynamic operation of the switching device is measured. This means that it is possible to measure in the switch-off process, but also in the switching-on process of the switching device. The latter was not possible in the prior art. By measuring when switching the switching device wear effects of the switching mechanism can be detected very well.

Claims (20)

1. Method for determining the remaining service life of a vacuum switching device, especially for detecting and displaying wear states of the vacuum switching device, including the switching device drive, by monitoring the contact resilience during switching for detecting at least the contact erosion in the switching device, with the following measures:

   - During the movement of the switching device drive, to monitor the contact resilience, time signals (t₀, t_D, t_δ) are determined for definition of two time intervals between significant events of the drive movement,

   - To detect and display contact erosion (d_erosion) on the one hand and wear (d_wear) of the switching device mechanism on the other hand by means of contact resilience monitoring a separate sensor is used,

   - at least one of the events is detected by the sensor for the purposes of determining the time interval (t_δ - t_D) between the significant events,

   - from the time interval (t_δ - t_D) relative contact resilience changes are computed which contain both the contact erosion (d_erosion) and also the mechanical wear (d_wear) in the switching device, and from this the remaining switching device service life is determined.
2. Method according to claim 1, characterized in that the measurements are taken during the switching-off process of the switching device.
3. Method according to claim 1, characterized in that the measurements are taken during the switching-on process of the switching device.
4. Method according to one of the claims 2 or 3, characterized by its use in vacuum contactors.
5. Method according to one of the previous claims, characterized in that the time interval is measured at one pole or simultaneously at a number poles of the switching device, especially as a simultaneous 3-pole measurement.
6. Method according to claim 5, characterized in that the detection and display of the switching contact erosion is undertaken individually for each pole in a 3-pole switching device.
7. Method according to one of the previous claims, characterized in that the events are detected electrically for time interval measurement.
8. Method according to one of the claims 1 to 6, characterized in that the events are detected optically for time interval measurement.
9. Method according to one of the claims 1 to 6, characterized in that the events are detected mechanically for time interval measurement.
10. The method according to one of the previous claims, characterized by a discrimination between contact erosion and mechanical switching device wear.
11. Method according to claim 10, characterized in that the detected changes in contact resilience are divided up into a proportion able to be assigned to contact erosion and a proportion able to be assigned to mechanical wear and are displayed separately.
12. Arrangement for determining the remaining service life of vacuum switching devices by executing the method as claimed in claim 1 or in one of claims 2 to 11, with contact pieces (17, 18), of which one is a fixed contact (17) and another a moving contact (18), with the moving contact being connected via a switching device mechanism (20 - 23) to a drive (100) for activating the vacuum switching device (10) for the purposes of carrying out a lifting movement of the moving contact (18), characterized in that the drive is assigned a sensor (225, 226; 127; 141; 151; 161) with which the wear state of all mechanical components of the switching device mechanism is detected (20 to 31).
13. Arrangement according to claim 12, characterized in that the sensor is a permanently assigned plunger coil (125) with a movable permanent magnet (126), with the permanent magnet (126) being attached to the spring mounting (22) of the switching device mechanism (20 to 31).
14. Arrangement according to claim 12, characterized in that the sensor is a piezo converter (137) which is attached to the spring mounting (22) of the switching device mechanism (20 to 31).
15. Arrangement according to claim 12, characterized in that the sensor is a light curtain (14) which is connected to the pin guide (16) of the moving contact (15).
16. Arrangement according to claim 12, characterized in that the sensor is a switch (51) which is connected to the spring mounting (22) of the switching device mechanism (20 to 31).
17. Arrangement according to claim 15, characterized in that the light curtain (141) is embodied by an optocoupler, a magnet with associated reed contact and/or a magnet with associated Hall sensor.
18. Arrangement according to one of claims 12 to 17, characterized in the version for a vacuum switching device, especially a vacuum contactor.
19. Arrangement according to one of claims 12 to 18, characterized by a computer for computation and display of the contact erosion on the one hand and of the mechanical wear in the switching device on the other hand.
20. Arrangement according to claim 19, characterized in that, in the computer the contact erosion in accordance with Eq. 8.2 $$\mathrm{Erosion}\left[\mathrm{\%}\right]\mathrm{=}\left(\mathrm{1}\mathrm{-}\left({{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\mathrm{\delta }}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\right)\mathrm{/}{\left({{\mathrm{t}}_{\mathrm{D}}}^{\mathrm{2}}\mathrm{-}{{\mathrm{t}}_{\mathrm{\delta }}}^{\mathrm{2}}\mathrm{/}\mathrm{2}\right)}_{\mathrm{new}}\right)\mathrm{*}\mathrm{100}$$

    

    
    and the mechanical wear in accordance with Gl. 11. $$\mathrm{mechanical\; wear}(\mathrm{\%}\mathrm{]}\mathrm{=}\left[\mathrm{(}\mathrm{(}{\mathrm{s}}_{\mathrm{2}}\left({\mathrm{t}}_{\mathrm{\delta }}\right)\mathrm{-}{\mathrm{s}}_{\mathrm{2}}{\left({\mathrm{t}}_{\mathrm{\delta }}\right)}_{\mathrm{new}}\mathrm{)}{\mathrm{s}}_{\mathrm{1}}{\left({\mathrm{t}}_{\mathrm{D}}\right)}_{\mathrm{new}}\right]\mathrm{*}\mathrm{100}$$

    

    
    is able to be determined, with s_i(t_D) meaning the path on switching on the drive and s_i(t_δ) the path on opening the switching contacts with i = first/second time interval or movement section.

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