Auxiliary fixture and method for testing a screw-in type capacitor

Abstract

The embodiment of the present application provides a kind of auxiliary fixture and the method for testing screw rod lead-out type capacitor.The auxiliary fixture includes: the fixture body made of first conductive material, the lower part of the fixture body is provided with screw hole, the screw hole is suitable for being engaged with the lead-out screw terminal of the capacitor by thread, the upper part of the fixture body is provided with clamping block;Spring leaf made of second conductive material, the spring leaf is sleeved on the clamping block, and forms the limiting groove pair suitable for stopping the test clamp when the clamping block is clamped by test clamp.The embodiment of the present application can avoid the measurement error caused by the shaking of measurement clamp and the change of measurement position due to human in the test process of screw rod lead-out type capacitor, can effectively improve the consistency of key parameters such as equivalent series resistance test, and improve test efficiency.

Description

Technical Field

[0001] This invention relates to the field of capacitor testing technology, and more particularly to an auxiliary fixture and a method for testing screw-lead type capacitors. Background Technology

[0002] Screw-lead type power capacitors are one of the fundamental components of various rail transit converter products. Accurate testing of key parameters such as capacitance, loss tangent, and equivalent series resistance is crucial for evaluating capacitor quality and condition. Currently, a bridge tester (e.g., an LCR bridge) is commonly used to test these key parameters. The testing method involves clamping the bridge's test clips onto the screw terminals of the capacitor. In this case, the contact between the bridge test clips and the screw terminals is point contact, and the bridge test clips need to be manually supported. The vibrations that occur when manually operating the bridge test clips cause fluctuations in the contact resistance between the bridge test clips and the capacitor screw terminals, and these fluctuations are directly reflected in the measured equivalent series resistance value. Furthermore, different operating habits and clamping positions can also lead to errors in the measurement results. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide an auxiliary fixture and a method for testing screw-lead type capacitors using the auxiliary fixture.

[0004] Based on the above objectives, embodiments of the present invention provide an auxiliary clamp, comprising: a clamp body made of a first conductive material, wherein a screw hole is provided at the lower part of the clamp body, the screw hole being adapted to engage with the lead screw terminal of the capacitor via threads, and a clamping block being provided at the upper part of the clamp body; and a spring made of a second conductive material, the spring being sleeved on the clamping block and forming a pair of limiting grooves adapted to hold the test clamp when the clamping block is clamped by the test clamp.

[0005] Based on the same inventive concept, embodiments of the present invention provide a method for testing screw-lead type capacitors using an auxiliary fixture, comprising:

[0006] With the clamp bodies of the pair of auxiliary clamps respectively engaged with a pair of screw samples via threads, and the pair of test clamps of the bridge tester respectively clamping the clamping blocks of the clamp bodies and being locked within the limiting grooves of the springs, the first resistance test result R of the bridge tester is obtained. C1 The screw sample has the same material and shape as the lead screw terminal of the capacitor;

[0007] With the clamp bodies of the auxiliary clamps respectively engaged with the two lead screw terminals of the capacitor via threads, and the clamping blocks of the clamp bodies respectively clamped by a pair of test clamps of the bridge tester and locked within the limiting grooves of the spring plates, the second resistance R of the bridge tester is obtained. C2 Test results.

[0008] R C2 With R C1 The difference is used as the equivalent series resistance R after the capacitor compensation calibration. S The test value. That is:

[0009] R S =R C2 -R C1

[0010] As can be seen from the above description, according to the embodiments of the present invention, the clamp body and the lead screw of the capacitor under test can be engaged by threads to ensure close contact. The contact area between the measuring clamp of the bridge tester and the auxiliary clamp is increased by a metal strip to reduce contact resistance, and the contact stability between the measuring clamp of the bridge tester and the clamp body is improved by a spring. This avoids measurement errors caused by human error during capacitor testing, such as clamp jitter and changes in measurement position. It effectively improves the consistency of testing key parameters such as equivalent series resistance and increases testing efficiency. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a schematic diagram of the auxiliary clamp structure according to an embodiment of the present invention.

[0013] Figure 2 This is a schematic diagram of the assembly of the auxiliary fixture before testing according to an embodiment of the present invention.

[0014] Figure 3 This diagram illustrates the equivalent series resistance analysis during actual testing of a traditional screw-type capacitor.

[0015] Figure 4 This is a schematic diagram illustrating the equivalent series resistance analysis during the testing of a screw-lead type capacitor using an auxiliary fixture, according to an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this invention should have the ordinary meaning understood by those skilled in the art. The terms "first," "second," and similar terms used in the embodiments of this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0018] As described in the background section, measuring key parameters of capacitors is an essential step in the manufacturing and use of capacitors. In the prior art, the measurement of key capacitor parameters often involves directly clamping the measuring clamp onto the capacitor's lead screw due to the lack of suitable auxiliary fixtures that match the measuring clamp of the testing instrument. This results in point contact between the measuring clamp and the capacitor under test, leading to high contact resistance and potential issues such as fluctuating resistance and clamp slippage. Furthermore, human error can cause significant operational errors, severely affecting the measurement results.

[0019] In view of this, the present invention proposes an auxiliary fixture and a method for testing screw-lead type capacitors using the auxiliary fixture. The fixture body and the lead screw of the capacitor under test are engaged by threads to ensure tight contact. A metal strip is used to increase the contact area between the measuring clamp of the bridge tester and the auxiliary fixture to reduce contact resistance. A spring is used to improve the stability of the contact between the measuring clamp of the bridge tester and the fixture body. The method for testing screw-lead type capacitors using the auxiliary fixture of the present invention measures an equivalent replacement screw sample using the auxiliary fixture to obtain a first resistance test result. Further, based on the resistance test result, the equivalent resistance value of the capacitor under test is measured.

[0020] The auxiliary fixture and application method of the present invention can avoid measurement errors caused by human error during the testing of power capacitors, such as jitter of the measuring clamp and changes in the measuring position. It can effectively improve the consistency of testing key parameters such as equivalent series resistance and improve testing efficiency.

[0021] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0022] refer to Figure 1 This is a schematic diagram of the auxiliary clamp structure according to an embodiment of the present invention.

[0023] The auxiliary clamp of this invention includes a clamp body 101 made of a first conductive material, wherein the first conductive material includes, but is not limited to, a metal material. A screw hole 102 is provided at the lower part of the clamp body 101, which is adapted to engage with the lead screw terminal of a capacitor via threads. The type of screw hole 102 includes, but is not limited to, connecting threads and transmission threads. The screw hole at the lower part of the clamp body 101 ranges from M4 to M32, and a clamping block 103 is provided at the upper part of the clamp body 101. In this embodiment, the clamp body 101 and the clamping block are integral. The auxiliary clamp of this invention also includes a spring 104 made of a second conductive material, wherein the second conductive material includes, but is not limited to, a metal material. The spring 104 is sleeved on the clamping block 103 and forms a pair of limiting grooves 106 adapted to hold the test clamp when the clamping block 103 is clamped by the test clamp. A metal strip 105 is wound around the clamping block 103. In this embodiment, the metal strip 105 is welded to the surface of the clamping block 103. The metal strip 105 is made of a metal material with excellent conductivity, such as copper, and is gold-plated to reduce contact resistance and improve oxidation resistance. In this embodiment, the metal strip 105 is a metal braided strip. By tightly winding and welding the metal strip 105 to the clamping block 103, the contact area between the measuring clamp and the auxiliary clamp can be increased, reducing contact resistance and thus minimizing the impact of contact resistance on the measurement results. The spring 104 improves the stability of the contact between the measuring clamp and the clamp body 101, avoiding inaccurate measurement results caused by fluctuations in contact resistance.

[0024] refer to Figure 2 This is a schematic diagram of the auxiliary fixture assembly before testing according to an embodiment of the present invention.

[0025] In this embodiment of the invention, an LCR bridge tester is used. The tester is connected to an auxiliary fixture via test leads with test clips. Specifically, when the test clips are clamped onto the clamping block of the auxiliary fixture, they are engaged with the limiting groove and make stable surface contact with the auxiliary fixture through the metal strip. The screw hole at the bottom of the fixture body is screwed onto the lead-out screw terminal of the capacitor under test, and the threads on the lead-out screw terminal of the capacitor under test are engaged. After all connections are completed, the test can be performed.

[0026] refer to Figure 3 This is a schematic diagram illustrating the equivalent series resistance analysis during actual testing of a traditional screw-type capacitor.

[0027] In practice, the bridge test clamp is typically clamped onto the lead-out screw terminals of the capacitor equivalent model manually. This point contact between the bridge test clamp and the screw terminals results in contact resistances R2 and R3 during testing. Furthermore, hand-operated jitter causes fluctuations in these contact resistances, directly impacting the measured equivalent series resistance. Additionally, different operator habits and clamp positions can lead to variations in the measured lead-out screw resistance R4, causing further errors. The line resistance R1 also contributes to the measurement. All these issues reduce the consistency and validity of the capacitor equivalent series resistance parameter test results.

[0028] Based on the same inventive concept, this disclosure also provides a method for testing screw-lead type capacitors using an auxiliary fixture, including:

[0029] With the clamp bodies of the pair of auxiliary clamps respectively engaged with a pair of screw samples via threads, and the pair of test clamps of the bridge tester respectively clamping the clamping blocks of the clamp bodies and being locked within the limiting grooves of the springs, the first resistance test result R of the bridge tester is obtained. C1 The screw sample has the same material and shape as the lead screw terminal of the capacitor;

[0030] With the clamp bodies of the auxiliary clamps respectively engaged with the two lead screw terminals of the capacitor via threads, and the clamping blocks of the clamp bodies respectively clamped by a pair of test clamps of the bridge tester and locked within the limiting grooves of the spring plates, the second resistance R of the bridge tester is obtained. C2 Test results.

[0031] R C2 With R C1 The difference is used as the equivalent series resistance R after the capacitor compensation calibration. S The test value. That is:

[0032] R S =R C2 -R C1

[0033] refer to Figure 4 This is a schematic diagram illustrating the equivalent series resistance analysis during the testing of a screw-lead type capacitor using an auxiliary fixture, according to an embodiment of the present invention.

[0034] In a specific implementation, when the clamp bodies of a pair of auxiliary clamps are respectively engaged with a pair of screw samples via threads, and the pair of test clamps of the bridge tester respectively clamp the clamping blocks of the clamp bodies and are locked within the limiting grooves of the springs, the first resistance R of the bridge tester is obtained. C1 The test results show that, in this embodiment of the invention, the screw sample and the lead screw terminals of the capacitor have the same material and shape. The screw sample can also be other test samples that can achieve an equivalent substitution effect with the capacitor under test. The first resistor R... C1 It consists of several parts: line resistance R1, contact resistances R2 and R3, and lead screw resistance R4, satisfying the following relationship:

[0035] R C1 =R1+R2+R3+R4

[0036] Furthermore, according to the first resistance test of the bridge tester, R... C1 As a result, the bridge tester was debugged and calibrated to eliminate the line resistance R1, contact resistances R2 and R3, and lead screw resistance R4 generated during the test. The lead screw resistance R4 is the resistance of the lead screw sample, which is an equivalent replacement for the lead screw of the capacitor under test. Therefore, this process can completely eliminate the resistance error of the lead screw of the capacitor under test.

[0037] Furthermore, in specific implementation,

[0038] With the clamp bodies of the auxiliary clamps respectively engaged with the two lead screw terminals of the capacitor via threads, and the clamping blocks of the clamp bodies respectively clamped by a pair of test clamps of the bridge tester and locked within the limiting grooves of the spring plates, the second resistance R of the bridge tester is obtained. C2 Test results.

[0039] R C2 With R C1 The difference is used as the equivalent series resistance R after the capacitor compensation calibration. S The test value. That is:

[0040] R S =R C2 -R C1

[0041] It should be noted that the above description describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims may be performed in a different order than that shown in the embodiments and still achieve the desired results. Furthermore, the processes depicted in the drawings do not necessarily require the specific or sequential order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0042] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in the details for the sake of brevity.

[0043] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An auxiliary fixture suitable for auxiliary testing of screw-lead type capacitors, characterized in that, include: The clamp body is made of a first conductive material, and the lower part of the clamp body is provided with a screw hole, which is adapted to engage with the lead screw terminal of the capacitor by thread, and the upper part of the clamp body is provided with a clamping block; A spring made of a second conductive material is sleeved on the clamping block and forms a pair of limiting grooves adapted to hold the test clamp when the clamping block is clamped by the test clamp.

2. The auxiliary clamp according to claim 1, characterized in that, The clamping block is wrapped with a metal strip.

3. The auxiliary clamp according to claim 2, characterized in that, The metal strip is welded to the surface of the clamping block.

4. The auxiliary clamp according to claim 3, characterized in that, The metal strip includes a metal braided strip.

5. The auxiliary clamp according to claim 4, characterized in that, The metal braided strip includes gold-plated copper wire braided strip.

6. The auxiliary clamp according to any one of claims 1 to 5, characterized in that, The first conductive material is a first metallic material, and the second conductive material is a second metallic material.

7. The auxiliary clamp according to claim 6, characterized in that, The second metallic material includes copper.

8. A method for testing a screw-lead type capacitor using an auxiliary fixture according to any one of claims 1 to 7, characterized in that, include: With the clamp bodies of the pair of auxiliary clamps respectively engaged with a pair of screw samples via threads, and the pair of test clamps of the bridge tester respectively clamping the clamping blocks of the clamp bodies and being locked within the limiting grooves of the springs, the first resistance test result R of the bridge tester is obtained. C1 The screw sample has the same material and shape as the lead screw terminal of the capacitor; With the clamp bodies of the auxiliary clamps respectively engaged with the two lead screw terminals of the capacitor via threads, and the clamping blocks of the clamp bodies respectively clamped by a pair of test clamps of the bridge tester and locked within the limiting grooves of the spring plates, the second resistance R of the bridge tester is obtained. C2 Test results; R C2 With R C1 The difference is used as the equivalent series resistance R after the capacitor compensation calibration. S The test value, that is: 。

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