EP1573761B1 - Method and device for determining the remaining service life of a switchgear - Google Patents

Abstract

In a switchgear, the switching contacts of a switchgear mechanism (100) are set to the on position or the off position, wherefore pressure is generated by the contact force spring in order to apply the pre-determined contact force in the on position. The service life of one such switchgear is determined by the erosion of switching contacts and by the mechanical wear of the switchgear mechanism. It is known that the switching contact erosion can be determined by detecting the change in pressure in the drive of the switchgear, According to prior art, the change in pressure is always measured during the switching-off process. According to the invention, the pressure change is detected during the switching-on process, and especially the mechanical wear of the switchgear can be simultaneously determined. The inventive device comprises a magnetic drive (100) consisting of an armature (110), a yoke (101) and magnetising coils (102, 102'), a position transmitter (120) being coupled to the magnetic armature (110) in a positively engaging manner.

Description

The invention relates to a method for determining the remaining service life of a switching device. In addition, the invention relates to an associated apparatus for carrying out the method.

For the reliability of switchgear, it is important to know the residual life of contactors in order to be able to be protected by timely maintenance measures, e.g. in contactors, by replacing the contacts, to avoid malfunction. Previously known methods evaluate the chronological sequence during the switch-off process. For contactors, in particular air guns, a method for residual life detection of contact erosion was developed in which the burn by measuring the time interval between armature opening - characterized by a characteristic peak in the coil voltage - and contact opening - characterized by the occurrence of a switching path voltage - the contact erosion and thus the Remaining life is measured.

Specifically, the method for detecting the change in through pressure as a substitute criterion for the contact erosion is provided by EP 0 694 937 B1 under protection. Specific methods for use with switching devices are described in EP 0 878 016 B1, EP 0 878 015 B1 and EP 1 002 325 B1. In so doing, it is always assumed that the changes in throughput during the switch-off process, i. be detected by an electromagnetic drive when opening the switch contacts, from which specifically determined the burnup of the switch contacts and from this the remaining life of the switching device is determined.

In addition, a method for determining the contact erosion is known from DE 199 15 978 A1, in which the change in distance the movable contact piece is monitored to the contact point. Specific embodiments of switches with different possibilities of Abbranderfassung are described in DE 100 28 559 A1 and EP 0 355 606 B1.

On this basis, it is an object of the invention to provide a method and the associated device in which in addition to the contact wear and the wear of the switching device mechanism can be considered under certain conditions. In addition, it is possible to monitor and control the switch-on movement with the acquired measured values.

The object is achieved by a method according to claim 1. An associated device is specified in claim 9. Further developments of the method and the associated device are the subject of the dependent claims.

According to the invention, the detection of the changes in pressure is now carried out especially during the switch-on process, i. when closing the switch contacts by the magnetic drive, with at least one position sensor takes place three times to three positions of the contacts. In the associated device, a position sensor is non-positively coupled to the contact for this purpose on the armature of the magnetic drive.

It is particularly advantageous in the invention that not only the contact erosion as the life of the switching device substantially determining size, but also the wear of the device mechanism is taken into account. This may be important if the switching device is specifically a vacuum contactor. While the contact stroke is comparatively large (up to 10 mm) in the case of air riflemen, and insofar as the play caused by the wear of the movable components of the device mechanics hardly matters, this can be a factor that can not be neglected in vacuum contactors.

The latter is given by the fact that the contact stroke is comparatively low in vacuum switches compared to air switching devices (up to 2 mm), but by the contact closing force, which is generated by applying force to the device mechanism and achievable only via lever force deflection and power transmission, wear and tear, especially at the pivot points the device mechanics can easily occur.

Figur 1

eine graphische Darstellung zur Berechnung der Kontakt-Schließposition beim Einschaltvorgang,

Figur 2

einen Magnetantrieb für ein Schaltgerät mit einem Positionssensor,

Figur 3

eine spezifische Ausbildung des Positionssensors aus Figur 2 zur Bestimmung einzelner Positionszeitpunkte,

Figur 4

eine zu Figur 3 konkretisierte Anordnung für ein Luftschütz zur Ermittlung von Kontakt-Schließpositionen x₃, x_3neu der Positionszeitpunkte und

Figur 5

ein Flussdiagramm zur rechnerischen Ermittlung der Kontaktlebensdauer eines Schaltgerätes.

Further details and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing in conjunction with the claims. Show it

FIG. 1

a graphic representation for the calculation of the contact closing position during the switch-on,

FIG. 2

a magnetic drive for a switching device with a position sensor,

FIG. 3

a specific embodiment of the position sensor from FIG. 2 for determining individual position times,

FIG. 4

an arrangement specified for Figure 3 for an air contactor for determining contact closing positions x ₃ , x _3neu the position _times and

FIG. 5

a flowchart for the mathematical determination of the contact life of a switching device.

The method described below for determining the remaining service life of switching contacts consists essentially in the timely detection of predetermined, discrete positions of a magnet armature of a contactor drive and / or certain components of the switching device drive and in the determination of the speed and the (average) acceleration of the component on which the Position measurement is made to these predetermined positions. In addition, it consists in the measurement of the switch-on of the switching contacts during their closing movement and the determination of the contact-closing positions relative to the detected, discrete positions.

1 shows schematically the path-time curve 1 of a component of the switching device whose path is identical to the contact path, the path either but also over a constant Factor or via a given function with the contact path can be mathematically linked.

ein Geschwindigkeitswert des Bauteiles ableitbar ist. Da das überwachte Bauteil während des Einschaltvorganges im allgemeinen eine beschleunigte Bewegung ausführt, wird neben der Geschwindigkeit v für wenigstens ein Zeitintervall, $$\mathrm{z}\mathrm{.}\mathrm{B}\mathrm{.}\mathrm{\Delta t}\mathrm{=}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{oder\; \Delta t}\mathrm{=}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{2}}\mathrm{,}$$

ein mittlerer Wert einer konstanten Beschleunigung bestimmt. Aus den ermittelten Werten der Geschwindigkeit und der Beschleunigung, sowie aus den Relativpositionen der Positionsgeber zueinander und ihrer Positionszeitpunkte, kann für den Kontaktschließzeitpunkt t₃ durch eine einfache mathematische Beziehung die Position des schließenden Kontaktes bestimmt werden.To determine the residual life, at least four points in time are recorded, one of which, eg, t ₃ , represents the contact closure time and the other, eg, t ₁ , t _2, and t _{4 represent} position times of one or more position encoders. At least two of these times, eg t ₁ and t ₂ , may be time values of two closely adjacent positions, from which by the relationship $$\mathrm{v}\mathrm{=}\mathrm{(}{\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\left({\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)$$

a speed value of the component is derivable. Since the monitored component generally performs an accelerated movement during the switch-on process, in addition to the speed v for at least one time interval, $$\mathrm{z}\mathrm{,}\mathrm{B}\mathrm{,}\mathrm{.delta.t}\mathrm{=}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\mathrm{or\; \Delta t}\mathrm{=}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{2}}\mathrm{.}$$

a mean value of a constant acceleration is determined. From the determined values of the speed and the acceleration, as well as from the relative positions of the position sensors to each other and their position times, the position of the closing contact can be determined for the contact closing time t ₃ by a simple mathematical relationship.

The still unknown contact closing position between the position x ₂ , which represents the end of the distance interval for speed determination, and the position x ₄ , which is in the closing direction of the component after the contact-closing position, is unknown. It can be seen that the closer the path interval between the positions x ₁ and x _{4 is} selected, the more accurate the contact closing position x ₃ can be determined. Ideally, positions x ₁ and x ₄ are chosen to confidently enclose the contact closing position due to contact and / or mechanical wear, but the path interval between them will not be significantly greater than the difference in contact closing positions at the beginning and end to the end of the contact life.

To solve the position / time detection results in several alternative methods, including the structure of the switching device drive is addressed:

FIG. 2 shows a known magnetic drive for a switching device and designates it as 100. It consists in a known manner, for example, E-shaped magnetic yoke with magnetic coils and a magnet armature.

In Figure 2, an associated switching device is specifically a contactor. This may be an air contactor but also a vacuum contactor, in the latter case, the articulation of the drive to the moving contacts of the contactor is more complex.

In Figure 2, a yoke is denoted by 101, sit on the two magnetic coils 102 and 102 'for magnetic excitation. The pole faces of the magnetic yoke are labeled 103 and 103 '. The magnet yoke 101 is associated with a magnet armature 110, which is attracted to the magnetic yoke by the magnet yoke upon excitation of the magnetic drive.

FIG. 2 shows the full opening position of the magnet armature 110. On the magnet armature, a carrier 130 is arranged for a moving contact 141, wherein in Figure 2, the carrier 130 is movable in the vertical direction. During the switch-on movement of the drive, the moving contact 141 is brought into the closed position to the fixed contact 151.

In FIG. 2, on the other side of the magnet armature facing the magnet yoke, a position transmitter 120 is arranged in frictional contact with the magnet armature 110. The position sensor 120 is essentially used to detect certain position times in the armature movement and will be described in more detail in the other figures.

FIG. 3 shows the magnetic drive with a specific embodiment of a position transmitter 120, whose advantages lie in its simplicity, robustness and precision in detecting the predetermined positions. As can be seen from FIG. 3, the constructively predeterminable number of positions to be detected can be considerably above the minimum number of three positions, ie (x ₁ , x ₂ and x ₄ ). The position sensor 120 is formed as a cylindrical rod, which is pressed by a spring 127 with moderate spring force against the armature 110 and can be moved in an associated housing 126. In the off state of the magnetic drive 100 of the position sensor 120 is located on the armature 110, which is taken during the switching movement of the armature 110 of the position sensor 120 and acting on him acceleration forces, but no impact forces. The cylindrical surface 121 of the position sensor 120 is in the axial direction in a plurality of conductive and non-conductive surface portions 122 to 124. Since the outer diameter of all surface portions 122 to 124 are identical and they join each other without a parting line, one obtains a smooth cylindrical surface of alternating axially in the axial direction conductive and non-conductive sections.

Such an electrically conductive portion may be e.g. a good conductive metallic ring 125 whose height is e.g. 1mm or less. The position detection can be done by electrical contact external contact members with this metal ring.

In order to keep the mechanical wear by abrasion between the contact members and the ring small, the contact can be realized instead by a sliding contact by a rolling contact. An electrical measuring circuit is connected to this measuring contact, which derives a voltage signal (on / off) from the contact signal (on / off). If, for example, the instantaneous closing speed of the component is 1 m / s, the measuring contact will deliver as the 1 mm passes high metal ring times of the switching edges of the voltage signal, which have a time interval of 1 millisecond. At each segment boundary of the surface sections, therefore, a time signal can be taken. The position sensor 120 according to FIG. 3 therefore provides an alternating square-wave voltage signal which coincides in time with the conductivity signal of the passing segmented cylinder jacket surface produced at the measuring contact.

FIG. 4 shows the contact apparatus 40 of an air contactor and the armature 110 with the position transmitter 120 on one side and the bridge carrier 130 on the other side corresponding to FIG. To the bridge support 130, the movable part of the contact apparatus is introduced with its components. Specifically, a contact bridge 140 with Bewegkontakten 141, 141 'attached to a spring housing 160 with abutment 161, wherein the contact bridge 140 is supported at open contacts by a contact force spring 165 against the bridge girder 130. By this arrangement, the moving contacts 141, 141 'relative to the fixed contacts 151, 151', which are mounted on contact carriers 150, 150, movable and in the open or closed position can be brought. The contact force spring 165 generates the contact force and the closing positions of armature and contact bridge determine the pressure of the spring.

From Figure 4, the geometric relationships which determine the position times t ₁ to t ₄ , wherein the same reference numerals are used as in Figure 3. Essential in this context is the determination of the encoder position x _3new in the new state of the contacts and the encoder position x ₃ in the used state of the contacts. Furthermore, the placemarks x ₁ (t ₁ ), x ₂ (t ₂ ) and x ₄ (t ₄ ) are shown. The contacts are formed as contact rings 122 to 124 and 125, 125 'around the cylindrical position sensor 120. It may also be sufficient to coat the surface 121 of the position sensor 120.

$${\mathrm{x}}_{\mathrm{4}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{=}\mathrm{v}\mathrm{*}\left({\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\right)\mathrm{+}\mathrm{0.5}\mathrm{*}{\mathrm{b}}_{\mathrm{m}}\mathrm{*}{\left({\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\right)}^{\mathrm{2}}\mathrm{,}$$

$${\mathrm{b}}_{\mathrm{m}}\mathrm{=}\mathrm{2}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{*}\left(\mathrm{(}{\mathrm{x}}_{\mathrm{4}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{-}\left({\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\right)\right)$$

To determine the position of the contact during contact closure, the speed between the closely adjacent positions x ₁ and x ₂ and the average acceleration between x ₁ and x _{4 are} required. The following applies: $$\mathrm{v}\mathrm{=}\mathrm{(}{\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{,}$$

$${\mathrm{x}}_{\mathrm{4}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{=}\mathrm{v}\mathrm{*}\left({\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)\mathrm{+}\mathrm{0.5}\mathrm{*}{\mathrm{b}}_{\mathrm{m}}\mathrm{*}{\left({\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)}^{\mathrm{2}}\mathrm{.}$$

$${\mathrm{b}}_{\mathrm{m}}\mathrm{=}\mathrm{2}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{*}\left(\mathrm{(}{\mathrm{x}}_{\mathrm{4}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{-}\left({\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)\right)$$

$$\begin{array}{cc}{\mathrm{x}}_{\mathrm{3}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}& \mathrm{=}\left({\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\right)\mathrm{/}\left({\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\right)\mathrm{*}\left({\mathrm{t}}_{\mathrm{3}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\right)\mathrm{+}\mathrm{(}\left({\mathrm{x}}_{\mathrm{4}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\right)\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{-}\mathrm{(}{\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{*}{\left({\mathrm{t}}_{\mathrm{3}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\right)}^{\mathrm{2}}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{.}\end{array}$$

This gives x ₃ for the contact closing position $${\mathrm{x}}_3\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{=}\mathrm{v}\mathrm{*}\left({\mathrm{t}}_3\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)\mathrm{+}\mathrm{0.5}\mathrm{*}{\mathrm{b}}_{\mathrm{m}}\mathrm{*}{\left({\mathrm{t}}_3\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)}^{\mathrm{2}}\mathrm{.}$$

$$\begin{array}{cc}{\mathrm{x}}_{\mathrm{3}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}& \mathrm{=}\left({\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\right)\mathrm{/}\left({\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)\mathrm{*}\left({\mathrm{t}}_{\mathrm{3}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)\mathrm{+}\mathrm{(}\left({\mathrm{x}}_{\mathrm{4}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\right)\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{-}\mathrm{(}{\mathrm{x}}_{\mathrm{2}}\mathrm{-}{\mathrm{x}}_{\mathrm{1}}\mathrm{)}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{2}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{*}{\left({\mathrm{t}}_{\mathrm{3}}\mathrm{-}{\mathrm{<figure-callout\; id="1"\; label="t"\; filenames="imgf0003.png"\; state="\{\{state\}\}">t</figure-callout>}}_{\mathrm{1}}\right)}^{\mathrm{2}}\mathrm{/}\mathrm{(}{\mathrm{t}}_{\mathrm{4}}\mathrm{-}{\mathrm{t}}_{\mathrm{1}}\mathrm{)}\mathrm{,}\end{array}$$

It can be seen that the change of the contact-closure position to calculate only the differences of the measured contact times t _i and the known position values are needed. A spatial adjustment for the determination of absolute position values is therefore not required.

In the new state of the contacts with the position sensor, the measured values of the component positions and the switch-on contact to become a channel (x ₃ -x ₁₎ is _recalculated on a microprocessor. Due to contact wear, possibly with additional mechanical wear, a current value of the travel is obtained during switching operation (x ₃ -x ₁ ).

The wear, for example in mm here is, by the difference of the calculated paths (x ₃ -x ₁₎ - _{redistributed} (x ₃ -x _1). When Kontaktabbrand this difference corresponds to the decrease in the through-pressure by reducing the contact piece thickness. If, in addition, there is a decrease in the permissible pressure due to wear of mechanical, force-transmitting parts of the device drive, the mechanical, reduced pressure drop is also recorded as part of the total reduction in permeate pressure since the contacts and the drive components are in frictional contact during the accelerated switch-on movement.

FIG. 5 illustrates the mathematical procedure with reference to a flowchart. The individual steps 201 to 212 are largely self-explanatory: About the start and a presetting of switchgear encoder data corresponding to the positions 201 and 202, the times t ₂ , t ₃ and t ₄ are determined according to position 205. From this, the output values x ₃ (t ₃ ) and x ₁ (t ₁ ) or their difference x ₃ -x ₁ can be calculated correspondingly. The difference (x ₃ -x ₁ ) _new - (x ₃ -x ₁ ) results in the current change in pressure according to item 210. According to item 211, the change in pressure is correlated with the life end of the contacts and, if the given conditions are met, according to position 212 finished the program. If this is not the case, the position 203 is returned and t ₁ , t ₂ and t ₃ are re-determined according to the positions 204, 205. Positions 206 and 208, respectively, provide test routines for averaging x ₃ -x ₁ .

After reaching the contact life end and the installation of new contacts, the current value (x ₃ -x ₁ ) is _newly determined at the beginning of a new life cycle, which implicitly includes the current state of wear of the switching device mechanism. This ensures a reliable assessment of contact wear in each subsequent life cycle.

A particularly advantageous development of the procedure described above is a speed control of the drive: For speed-controllable drives, in particular contactor drives, which consist of a controllable, magnetic drive, the speed v measured with the position sensor can be used to iteratively set the drive to a predetermined speed , or to limit the speed to a predetermined value range. For this purpose, the control parameters with each switching on of the drive with a predetermined parameter step in the direction of higher speed, as long as the speed is less than the setpoint or less than the setpoint range, or set to lower speed as long as the speed is greater than the setpoint or above the setpoint range. This ensures that the contacts close after reaching the speed setting with the specified speed.

t_Beginn =

den Zeitpunkt des Anlegens von Spannung an die Spule entweder

• unter Berücksichtigung der Phasenlage der Spannung zur Erfassung der unterschiedlichen Kraftentwicklung oder
• unter Einsatz eines phasengesteuerten Zuschaltens, was der Herbeiführung von Synchronismus dient.

t_Ende =

Erfassung des Kontaktschließens, wozu die Schaltstreckenspannung gemessen wird.

An alternative to the procedure described above results from the determination of two points in time t _beginning and t _end for the sequence of the switch-on process and the residual life calculated therefrom. It means:

t _beginning =

the time of applying voltage to the coil either

• taking into account the phase position of the voltage to detect the different force development or
• using phased switching, which serves to provide synchronism.

t _end =

Detecting the contact closing, for which the switching path voltage is measured.

A particular advantage is that the method can be applied to existing shooters. However, this requires the detection of the voltage waveform with an A / D converter or zero-crossing detection on the control voltage.

To evaluate the switch-on from the times t _beginning and t _end , the predetermined and empirically determinable path-time curve of the magnetic drive according to Figure 1 is used. The change of the Einschaltweges in use state with respect to the new condition then provides a direct or proportional measure in the change in the contact piece thickness.

t_Beginn =

Zeitpunkt des Kontaktschließens, wozu die Schaltstreckenspannung gemessen wird.

t_Ende =

Erfassung eines Wegepunktes, entweder wenn

• das Magnetsystem schließt, wobei die Messung z.B. durch Anlegen einer Spannung erfolgt, die Joch-Anker-Bewegung und ein Spannungsnullwert gemessen wird, oder
• ein Schalter am Magnetsystem oder beliebigem Wegepunkt angebracht wird.

Alternatively, the determination of two other times t _beginning and t _end for the sequence of the switch-on and calculated from this residual life. The measured variables are defined as follows:

t _beginning =

Time of contact closure, for which the switching path voltage is measured.

t _end =

Detecting a waypoint, either when

• closing the magnet system, wherein the measurement is carried out, for example, by applying a voltage, the yoke-armature movement and a voltage zero value is measured, or
• a switch is attached to the magnet system or any waypoint.

From the empirically given according to Figure 1 path-time curve of the magnetic drive, a pressure value of the contact force spring is determined and determined from the change in use, the wear-related change in pressure. Advantage of this method is a simple detection of the timestamps. However, a modification of the contactor structure and thus a redesign may be required for the method.

In the first alternative, an advantageous embodiment of a speed control of the drive can be carried out as follows: By means of several position rings on a position sensor, it is possible to measure the path during the armature movement and to achieve an almost constant speed for closing the switching device by controlling the magnetic force. As a result, not only the switching movement is optimized, but also the forces causing the wear on the mechanically moving parts are minimized as much as possible.

Claims (18)

1. Method for determining the remaining service life of a switchgear, the service life of which is conditional upon switching contact erosion on the one hand and mechanical wear of an associated switchgear mechanism on the other hand, having switching contacts (141,141',151,151'), which are switched by the switchgear mechanism to an on or off position, with a through-pressure of a contact force spring (127) being produced in order to apply a predetermined contact force in an on position, and with the switching contact erosion in particular being determined by detecting the through-pressure change,
   characterised in that the following measures are carried out

   - the through-pressure change is detected during the switching-on process of the switchgear,

   - the switching contact erosion on the one hand and the mechanical wear of the switchgear mechanism on the other hand are determined by detecting the through-pressure change during the switching-on process

   - to which end at least one position sensor (120) is used, by means of which at least three time points are determined during the switching-on process at three positions of the contacts.
2. Method according to claim 1,
   characterised in that
   the closing speed of the contact/s is determined from two of the positions and associated time points.
3. Method according to claim 1,
   characterised in that
   the increase or decrease in the closing speed is determined from the third time point of the third position.
4. Method according to one of the preceding claims,
   characterised in that
   the contact position is calculated from the contact closing time.
5. Method according to claim 4,
   characterised in that
   the through-pressure change is determined from the change in the contact position.
6. Method according to claim 1,
   characterised in that
   a temporal determination of predetermined positions of the moveable components of the switchgear mechanism of the switchgear is carried out in order to detect the through-pressure.
7. Method according to claim 1,
   characterised in that
   a determination of the speed and/or of the acceleration of moveable components of the switchgear mechanism on the one hand and a measurement of the switching-on time points of the switching contacts during their closing movement are carried out in order to detect the through-pressure.
8. Method according to one of the preceding claims,
   characterised in that
   the speed of the moveable components is controlled during the switching-on process.
9. Device for implementing the method according to claim 1 or one of claims 2 to 9, with the switchgear being a contactor, with which the motion contacts (141, 141') are switched, by means of the magnetic armature (110) of a magnetic drive (100), which is formed from the armature (110), yoke (101) and magnet coils (102, 102'), to an on or off position, characterised in that
   a position sensor (120) is coupled in a non-positive manner to the magnetic armature (110).
10. Device according to claim 9,
    characterised in that
    ring contacts (122 to 124) are present on the position sensor (120) to detect a position.
11. Device according to claim 9,
    characterised in that
    contact rollers (125) are arranged on the position sensor (120) to provide position-dependent contact.
12. Device according to claim 11,
    characterised in that
    the position sensor is designed as a cylindrical rod (120), the cylindrical outer surface (121) of which is subdivided in the axial direction into a number of conductive and nonconductive surface segments (122-124).
13. Device according to one of claims 9 to 12,
    characterised in that
    a relative position (x ₃) of the contact can be derived at the sensor positions (x ₁ x ₂ x ₃) from the contact closing time point (t ₃) using the position sensor, it being possible to determine contact erosion from the change therein compared with a new value (x _3new ).
14. Device according to claim 13,
    characterised in that
    the remaining service life can be determined from the relative contact positions (x₃) in the used state and in the new state (x _3new ).
15. Device according to one of claims 9 to 14,
    characterised by
    means for calculating and displaying the remaining service life of the switchgear.
16. Device according to claim 15,
    characterised in that
    the means comprise a computer, in the storage device of which a path-time curve is stored.
17. Device according to claim 16,
    characterised in that
    the closing path can be determined from the predetermined path-time curve by detecting the start of the armature movement (t_start ) when switching-on and the contact closing time point (t_end ) during the switching-on process and that the change in the contact piece thickness can be calculated from a change in the closing path, with the change in the contact piece thickness corresponding to the erosion.
18. Device according to claim 16,
    characterised in that
    a part of the armature path can be determined from the contact closing time point (t_start) and a time point (t_end) of a predetermined armature position with the aid of the predetermined path-time curve, from the change in which a change in the through-pressure of the contact force spring can be derived.

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