Contact measurement system and method for measuring parameters of contacts of a switchgear

Abstract

The present invention relates to a contact measurement system and method for measuring parameters of a contact of a switching device, and more particularly to a contact measurement system for measuring parameters of a contact of a switching device, comprising a first device configured to measure the resistance of the contact and spatially and / or dynamically map the resistance; a second device configured to measure the axial force of the contact and spatially and / or dynamically map the axial force; and a third device configured to measure the position of the contact; wherein the contact measurement system is configured to determine a force characteristic that depends on a position based on the measured axial force of the contact and the position of the contact; wherein the contact measurement system is configured to determine a state of the contact based on a combination of the force characteristic that depends on the position and the resistance of the contact.

Description

Technical Field

[0001] The present invention relates to a test device for the inspection task of female contacts in LV switchgear. In particular, the present invention relates to a contact measurement system and a method for measuring parameters of contacts of a switchgear. Background Art

[0002] Because the female and male contacts of switchgear are subject to electrical and mechanical wear, they need to be inspected during planned maintenance intervals. Therefore, a test method is needed to infer the contact condition.

[0003] It is mainly the female contact that needs to be checked, since this includes the thin lamella (sometimes called petal) that ensures good electrical conduction.

[0004] The two main parameters that are of interest are:

[0005] Resistance and contact force. Too high a resistance will result in electrical losses and excessive heating. Low contact force will result in poor contact performance during a short circuit event, as high forces during such an event can result in physical separation of the contacts, thus causing an arc to form.

[0006] As an indirect effect of too low a contact force is an increase in contact resistance. These problems need to be addressed. Summary of the invention

[0007] It would therefore be advantageous to have an improved technique for measuring contacts of switchgear.

[0008] The objects of the invention are solved by means of the subject-matter of the independent claims, wherein further embodiments are incorporated in the dependent claims.

[0009] In a first aspect, a contact measurement system for measuring parameters of a contact of a switching device is provided, comprising a first device configured to measure the resistance of the contact and spatially and / or dynamically map the resistance; a second device configured to measure the axial force of the contact and spatially and / or dynamically map the axial force; and a third device configured to measure the position of the contact; wherein the contact measurement system is configured to determine a position-dependent force characteristic based on the measured axial force of the contact and the position of the contact; wherein the contact measurement system is configured to determine a state of the contact based on a combination of the position-dependent force characteristic and the resistance of the contact.

[0010] In this way, a test device is provided which enables monitoring of the contact condition by measuring the peak sliding force when the male contact is pulled out of the connection, although according to the prior art, and achieves improved measurements. The condition of any contact can be defined by three separate measurements: visual inspection, resistance measurement and contact force measurement. The present measurement system allows comprehensive and thus combined measurements of resistance, axial force and position.

[0011] In this way, a test device is provided which enables a measurement of the contact quality: a measurement of the sliding force versus position is combined with a measurement of the electrical resistance.

[0012] The present invention achieves an indication of contact quality; contamination, aging and lubrication caused by field conditions have an impact on contact quality, and the impact of contamination, aging and lubrication caused by field conditions on contact quality can be identified by combining the measurement of sliding force relative to position with the measurement of resistance.

[0013] Thereby, a position-dependent force characteristic can be derived.The combination of resistance and force / position characteristic allows a suitable in-situ inspection of the general status of the sheet and the current situation.

[0014] The proposed solution also dynamically maps the contact force (sliding force or radial force), ie maps the contact force versus position when inserting and / or withdrawing the male test pin.

[0015] The test pin is similar to the pin used in medium voltage switchgear, but can be adapted to support the measurement. The performance of the contacts during operation is mainly determined by the radial forces.

[0016] In a second aspect, a disclosed method is provided which allows various information about the contact condition to be extracted from the dynamic measurement.

[0017] A second aspect of the present invention relates to a contact measurement method for measuring parameters of a contact of a switching device, the method comprising the following steps: measuring the resistance of the contact by means of a first device and mapping the resistance spatially and / or dynamically; measuring the axial force of the contact by means of a second device and mapping the axial force spatially and / or dynamically; and measuring the position of the contact by means of a third device; wherein the method further comprises the following steps: determining a position-dependent force characteristic based on the measured axial force of the contact and the position of the contact; wherein the method further comprises the following steps: determining the state of the contact based on a combination of the position-dependent force characteristic and the resistance of the contact.

[0018] In an example, the method may be combined with the measurement of contact resistance.

[0019] To conventionally provide current, the two bodies are mechanically joined. In some applications, dedicated thin sheets are embedded to provide good electrical contact. Depending on, for example, switching cycles, current transfer duration, overcurrent due to external faults (such as short circuits), these thin sheets can be broken down or damaged.

[0020] In other words, the present invention relates to a testing method for inferring the condition of such a female electrical contact, for example a female electrical contact having a petal-shaped contact.

[0021] In an exemplary embodiment of the present invention, a contact measurement system is configured to scan a surface of a switchgear.

[0022] In an exemplary embodiment of the present invention, the contact is a female contact or a male contact.

[0023] In an exemplary embodiment of the invention, the contact is measured on an embedded component of the switchgear.

[0024] In an exemplary embodiment of the present invention, the contact measurement system is portable.

[0025] In an exemplary embodiment of the present invention, the contact measurement system is non-portable.

[0026] In an exemplary embodiment of the invention, the contact measurement system comprises a hollow surrounding shaft which houses an electrically isolated pin and which is used by a first device for measuring the electrical resistance of a contact.

[0027] In an exemplary embodiment of the present invention, the first means for measuring resistance comprises a 4-point measurement setup.

[0028] In an exemplary embodiment of the present invention, the first means for measuring resistance comprises a 3-point measurement setup.

[0029] In an exemplary embodiment of the invention, the first device is configured to perform the measurement of the resistance by connecting a voltage measurement at any point in the electrical path of the extractable module.

[0030] In an exemplary embodiment of the present invention, the third device is configured to be shut down in a suspend mode, and wherein the contact measurement system is configured to determine the force characteristic based on the measured axial force of the contact; wherein the contact measurement system is configured to determine the state of the contact based on a combination of the force characteristic and the resistance of the contact.

[0031] The above aspects and examples will be apparent from and elucidated with reference to the embodiments described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Exemplary embodiments will be described below with reference to the following drawings:

[0033] Figure 1 A schematic illustration showing the concept of 4-point measurement according to an exemplary embodiment of the present invention is shown;

[0034] Figure 2 shows an example of a 4-point measurement setup on the outside according to an exemplary embodiment of the present invention;

[0035] Figure 3 shows an example of a 4-point measurement on a tip according to an exemplary embodiment of the present invention;

[0036] Figure 4 An example of a 4-point measurement setup according to an exemplary embodiment of the present invention is shown;

[0037] Figure 5 An example of a 4-point measurement setup in any location according to an exemplary embodiment of the present invention is shown;

[0038] Figure 6 shows an example of a cross-sectional view of a test device according to an exemplary embodiment of the present invention;

[0039] Figure 7 An example of a test device according to an exemplary embodiment of the present invention is shown;

[0040] Figure 8 shows an overview of an example of a contact device according to an exemplary embodiment of the present invention;

[0041] Fig. 9 shows an example of a line graph of force versus position according to an exemplary embodiment of the present invention;

[0042] Fig.10 Several regions of information of a sliding force versus position curve are shown according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0043] Figure 1 A general schematic diagram of a developed test device according to an exemplary embodiment of the present invention is shown. The test device may include a hollow surrounding shaft that houses an electrically isolated pin. The red components in the schematic are the components of interest.

[0044] With a 4-point measurement setup, the resistance of the red device can be measured directly. The middle pin is spring loaded to provide sufficiently good current transfer to the female contact. Alternatively, a 3-point measurement can be used when the electrical connections of the current source and voltage measurement pins can be defined during the construction of the test device.

[0045] For female contacts ( Figure 1For voltage measurement on the blue component in the figure, several alternatives can be used:

[0046] According to an exemplary embodiment of the present invention, Figure 2 The measurements on the outside of the female contact are shown in . In this case, the insulating cover of the female contact will need to be modified.

[0047] Figure 2 An example of a 4-point measurement setup on the outside according to an exemplary embodiment of the present invention is shown.

[0048] In an exemplary embodiment, it is also possible to use Figure 2 The middle pin shown in the figure performs the voltage measurement.

[0049] Measurements on LV switchgear equipment not in Figure 1 The advantage would be simple access without the need to modify the insulating cover.

[0050] Figure 3 An example of a 4-point measurement on a tip according to an exemplary embodiment of the present invention is shown.

[0051] According to an exemplary embodiment of the present invention, Figure 3 The measurements on the top of the female contact are shown in . In this case, a dedicated surface on the male contact will be required.

[0052] Figure 4 An example of a 4-point measurement setup according to an exemplary embodiment of the present invention is shown.

[0053] According to an exemplary embodiment of the present invention, Figure 4 Measurements made with a third electrical pin extending inside the pin are shown in .

[0054] Figure 5 An example of a 4-point measurement setup in any location according to an exemplary embodiment of the present invention is shown.

[0055] The measurement is accomplished by connecting a voltage measurement anywhere in the electrical path of the removable module. Ideally, the electrical connection will be accessible from Figure 5 The removable modules are accessible from the front.

[0056] As a second physical measurement, the axial (sliding) force during insertion or extraction is of interest. Therefore, the entire device is connected in series with a force sensor and a position sensor, which enables force and position relationship measurement.

[0057] Figure 6 An example of a cross-sectional view of a testing device according to an exemplary embodiment of the present invention is shown.

[0058] Figure 7An example of a testing device according to an exemplary embodiment of the present invention is shown.

[0059] To allow for series assembly, the spring loaded current probe is T-shaped so that the required electrical connection can be made. Figure 7 A CAD model of the test rig is shown.

[0060] Figure 8 An overview of an example of a contact device according to an exemplary embodiment of the present invention is shown.

[0061] Figure 8 An overview of a contact device is given, which includes a male pin and its tip, a contact sheet and a female contact part.

[0062] Fig. 9 An example of a force versus position graph is shown according to an exemplary embodiment of the present invention.

[0063] Fig. 9 Multiple locations are shown.

[0064] Position 1: Male pin is outside of female contact

[0065] Position 2: The top of the male pin begins to enter the female contact

[0066] Position 3: The male pin enters the sheet. A large force is required at the beginning to deform the sheet.

[0067] After this initial deformation, the sliding force remains stable at a low value.

[0068] Position 4: The male pin enters the lower part of the female contact and is centered.

[0069] Position 5: The male pin directly contacts the female contact and stops moving.

[0070] Fig.10 Several regions of information of a sliding force versus position curve are shown according to an exemplary embodiment of the present invention.

[0071] Fig.10 An example is given for regional analysis.

[0072] Fig.10 Examples are given for determining and identifying different locations:

[0073] Region A:

[0074] The force measurements on the inward and outward sections need to be equal and can be used to define the zero level of the sliding force. The deviation of the inward and outward force measurements indicates the drift of the force sensor used for the force measurement. Therefore, it can be used to check the quality of the measurement. In addition, this information can be used to compensate for the drift.

[0075] Region B:

[0076] The maximum force on the inward section precisely defines where the slice begins (area B1) and where the slice ends (area B2). From the stop position, the depth of the contact can be determined (area B3). This information about the physical dimensions of the contact can be used to identify the contact type and additional specifications.

[0077] Region B1: At this location, the male pin enters the sheet and deforms it. Therefore, if a suitable model is used that includes the velocity, dimensional parameters of the tip of the male pin and the material parameters of the tip of the male pin, the radial force F can be extracted from this measurement. r。

[0078] Region C: The sliding force can be inferred from this measurement section. A comparison of the data from regions C and D can be used to determine whether the male contact is well centered. Here, there is only a single mechanical guide, which is positioned in front of the lamella.

[0079] Region D: The sliding force can be inferred from the measurement section. A comparison of the data from regions C and D can be used to determine if the male contact is well centered. Here, dual mechanical guides, positioned before and after the sheet.

[0080] The curves measured in Section C and Section D on the inward and outward sections can be further analyzed. The average value is an indication of the contact force, and the fluctuation is a measure for the roughness of the contact. s =μF r , the sliding force and the radial force are related via the friction coefficient μ. Both contact surfaces are metallic.

[0081] During the above measurement, at least one measurement of the contact resistance can be performed. Information from the force and position relationship measurement can be used to trigger (multiple) contact resistance measurements. More than one contact resistance measurement can be completed to achieve more statistics or to measure the contact resistance at a certain contact force.

[0082] Although the present invention has been shown and described in detail in the drawings and the foregoing description, such showing and description are to be considered as illustrative or exemplary rather than restrictive. The present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and implemented by those skilled in the art in practicing the claimed invention by studying the drawings, the disclosure, and the dependent claims.

Claims

1. A contact measurement system for measuring parameters of a contact of a switch device, comprising: a first device configured to measure the resistance of the contact and to spatially and / or dynamically map the resistance; a second device configured to measure an axial force of the contact and to spatially and / or dynamically map the axial force; as well as a third device configured to measure the position of the contact; wherein the contact measurement system is configured to determine a position-dependent force characteristic based on the measured axial force of the contact piece and the position of the contact piece; wherein the contact measurement system is configured to determine a state of the contact piece based on a combination of the position-dependent force characteristic and a resistance of the contact piece, wherein said first means for measuring said resistance comprises a 4-point measurement setup, and wherein said first means are configured to perform the measurement of said resistance by connecting a voltage measurement anywhere in the electrical path of the extractable module.

2. The contact measurement system according to claim 1, characterized in that: The contact measurement system is configured to scan a surface of the switchgear.

3. The contact measurement system according to claim 1, characterized in that: The contact is a female contact or a male contact.

4. The contact measurement system according to any one of claims 1 to 3, characterized in that: The contact piece is an embedded component of the switching device.

5. The contact measurement system according to any one of claims 1 to 3, characterized in that: The contact measurement system is portable.

6. The contact measurement system according to any one of claims 1 to 3, characterized in that: The contact measurement system is non-portable.

7. The contact measurement system according to any one of claims 1 to 3, characterized in that: The contact measurement system comprises a hollow surrounding shaft which houses an electrically isolated pin and which is used by the first device for measuring the resistance of the contact.

8. The contact measurement system according to any one of claims 1 to 3, characterized in that: The first means for measuring the resistance comprises a 3-point measurement setup.

9. The contact measurement system according to any one of claims 1 to 3, characterized in that: The third device is configured to be turned off in a pause mode, and wherein the contact measurement system is configured to determine a force characteristic based on the measured axial force of the contact; wherein the contact measurement system is configured to determine the state of the contact based on a combination of the force characteristic and the resistance of the contact.

10. A contact measurement method for measuring parameters of a contact of a switch device, the method comprising the following steps: measuring the resistance of the contact by means of a first device and mapping the resistance spatially and / or dynamically; measuring the axial force of the contact element by means of a second device and mapping the axial force spatially and / or dynamically; and measuring the position of the contact member by means of a third device; wherein the method further comprises the steps of: determining a position-dependent force characteristic based on the measured axial force of the contact and the position of the contact; wherein the method further comprises the steps of: determining a state of the contact based on a combination of the position-dependent force characteristic and the resistance of the contact, wherein said first means for measuring said resistance comprises a 4-point measurement setup, and wherein said first means are configured to perform the measurement of said resistance by connecting a voltage measurement anywhere in the electrical path of the extractable module.

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