Auxiliary device for measuring DC resistance of main transformer low voltage side pipe and its parameter calculation method

Abstract

The present invention provides a device for measuring the DC resistance of a main transformer low-voltage side pipe mother and a method for calculating its parameters. The device includes a bracket body, which is a U-shaped opening. A first contact finger and a second contact finger are respectively arranged on the concave surface of the U-shaped opening of the bracket body. The first contact finger and the second contact finger are respectively arranged on the left and right sides of the concave surface of the bracket body and fixed on the bracket body. The first contact finger and the second contact finger are both elastic and arc-shaped, and the arc-shaped concave surface of the first contact finger and the second contact are in the same direction as the concave surface of the bracket body. A wiring terminal is arranged on the bracket body relative to the outer side of the concave surface. The present invention can be well engaged on the pipe mother or the pipe mother clamp through the cooperation of the bracket body and the elastic contact finger, ensuring a more fitted contact surface. In cooperation with other contact devices on site, the DC resistance of the reactive pipe mother on the low-voltage side of the main transformer can be measured, thereby ensuring the accuracy of the measurement, facilitating on-site maintenance operations, and reducing the damage of maintenance operations to the equipment to be repaired.

Description

Technical Field

[0001] The invention relates to a main transformer low-voltage side tube mother DC resistance measurement auxiliary device and a parameter calculation method thereof, belonging to the technical field of power detection. Background Art

[0002] The electrical conductive circuit is always composed of several components, in which two parts are in contact with each other through mechanical connection to achieve conductivity, and their contact surface is called conductive contact surface. In the substation, whether it is a transformer, switch or busbar, there are many such conductive contact surfaces. The contact surface of the electrical contact will always be covered by some substances with poor conductivity. The increase in resistance due to this reason is called surface resistance. Such substances include oxides, sulfides, dust, dirt, oil film, water film, etc. Oxides are mostly semiconductors with high resistivity. Any metal surface that looks very smooth to the naked eye is actually rough and uneven. When the two metal surfaces are in contact with each other, only a few protruding points (small faces) have real contact, and only a small number of spots with metal contact or semi-metal contact can conduct electricity. When the current passes through these small conductive spots, the current line will inevitably shrink. The current line shrinks, the current path flowing near the conductive spot increases, the effective conductive cross-section decreases, and the resistance value increases accordingly. This additional resistance formed by the contraction of the current line is called contraction resistance, which is another component of the contact resistance. The main phenomenon of current passing through the electrical contact between two conductors is the occurrence of local high temperature at the contact point. The reason for this phenomenon is that there is an additional resistance at the electrical contact, called contact resistance, which includes the above-mentioned surface resistance and contraction resistance.

[0003] In recent years, there have been several incidents of forced shutdown of equipment due to heating of contact surfaces in the power system. The reason is that the contact resistance of the conductive contact surface is not well controlled, which leads to the rise of contact resistance and heating. Therefore, the system has issued a document requiring multiple measures to control the occurrence of heating defects.

[0004] The contact resistance measurement of the lap joint between the mother tube and the clamp on the low-voltage side of the 500kV main transformer has always been a key test item for contact resistance measurement in the substation. Due to the large outer diameter of the mother tube, it is not suitable for the wire clamp equipped with the loop resistance meter. At present, the site can only press the wire clamp mouth on the mother tube, which leads to obvious inaccuracy in data measurement. Even if the process links such as the contact surface have met the requirements, it often does not meet the 10uΩ requirement stipulated by the company, and increases the risks of operations such as climbing and using scaffolds, or the parameters are calculated by special tools specific to a certain type of mother tube, but it is easy to reduce the versatility. Summary of the invention

[0005] The invention aims to provide a test fixture specially for a tube mother or a tube mother clamp, because the wire clamp equipped with the current loop resistance meter is not suitable for the outer diameter of the tube mother.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions.

[0007] The present invention provides a main transformer low-voltage side mother DC resistance measurement auxiliary device, comprising a bracket body, the bracket body is a U-shaped opening, a first contact finger and a second contact finger are respectively arranged on the concave surface of the U-shaped opening of the bracket body, the first contact finger and the second contact finger are respectively arranged on the left and right sides of the concave surface of the bracket body and fixed on the bracket body; the first contact finger and the second contact finger are both elastic and arc-shaped, and the arc-shaped concave surfaces of the first contact finger and the second contact are in the same direction as the concave surface of the bracket body; a wiring terminal is arranged on the bracket body relative to the outer side of the concave surface.

[0008] Furthermore, a first spring is arranged between the first contact finger and the bracket body, one end of the first spring is connected to the first contact finger, and the other end is connected to the bracket body; a second spring is arranged between the second contact finger and the bracket body, one end of the second spring is connected to the second contact finger, and the other end is connected to the bracket body, and the first spring and the second spring correspond in position.

[0009] Furthermore, one end of the U-shaped opening of the bracket body is connected to the operating rod.

[0010] Furthermore, the bracket body includes a left bracket and a right bracket, and the left bracket and the right bracket are connected and fixed by a connecting piece.

[0011] Furthermore, one end of the U-shaped opening of the bracket body also includes a bending portion, and the bending portion and the bracket body are an integral structure.

[0012] Furthermore, the first contact finger and the second contact finger are riveted to the bracket body by rivets.

[0013] Furthermore, the first spring and the second spring are riveted to the bracket body by rivets.

[0014] On the other hand, in order to provide a parameter calculation method for the device, the present invention also provides a parameter calculation method for a main transformer low-voltage side mother DC resistance measurement auxiliary device, including: the size of the U-shaped opening of the device is divided into two grades: Φ160~Φ200 and Φ200~260.

[0015] Furthermore, a torsion spring is selected as the first spring and the second spring, and the parameters of the first spring and the second spring are determined as follows:

[0016] (1) Determine the force parameters: Determine the clamping force at the contact point based on the diameter of the tube mother and the diameter of the tube mother clamp;

[0017] (2) Determine the torque parameters: According to the dimensions of the device, preliminarily determine the torsion arm of the spring. If a double torsion spring structure is used, the torque borne by each spring is half of the total torque. Determine the installation torque T 1 and working torque T 2 ;

[0018] (3) Determine other parameter requirements, including: determine the material according to the actual service life requirements;

[0019] Determine the allowable bending stress of the selected spring by calculating the cyclic characteristic γ, expressed as: Determine the loop characteristic γ and 10 in the manual 7 The ordinate of the intersection point of the lines is determined by the relationship between the ordinate and the material tensile strength R m The product of determines the allowable bending stress [σ] of the spring; calculates the wire material diameter d,

[0020] Where T is the torque of each spring, K b is the intermediate variable,

[0021] According to the spring inner diameter D 1 The winding ratio C is determined by the diameter d of the steel wire material. The formula is as follows: Where D is the spring median diameter: D = D 1 +d;

[0022] Calculate the spring stiffness T' and torsional deformation angle θ according to the following formula 1 ° and θ 2 °,

[0023]

[0024]

[0025]

[0026] Use the following formula to calculate the effective number of spring coils n:

[0027]

[0028] E is the elastic modulus of the material; l 1 is the torsion arm length on one side of the torsion spring; l 2 is the length of the torsion arm on the other side of the torsion spring;

[0029] According to the test bending stress σ s , then the test torque T s And the change angle θ under the test torque s °The calculation formula is as follows:

[0030]

[0031]

[0032] Dn is the spring diameter; n is the effective number of coils of the spring,

[0033] Calculate the guide rod diameter D', the formula is as follows:

[0034] D′=0.9(D 1 -ΔD s )

[0035] Calculate the free length H 0 , the formula is as follows:

[0036] H 0 =(nt+d)+L 0 ,

[0037] L 0 is the length of the torsion arm on the axis, n is the effective number of coils of the spring; t is the spring pitch, calculate the spring expansion length L, the formula is: L≈πDn+L 1 , L 1 is the length of the torque arm.

[0038] Furthermore, the fatigue life of the spring is determined as follows:

[0039]

[0040] where σ max Maximum allowable bending stress of the spring, σ min The minimum allowable bending stress of the spring is used to determine the ratio of the maximum allowable bending stress of the spring to the allowable stress of the material selected for the spring, as well as the ratio of the minimum allowable bending stress of the spring to the allowable stress of the material selected for the spring. The fatigue life of the spring is determined based on the comparison results.

[0041] Beneficial technical effects achieved by the present invention:

[0042] The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother provided by the present invention can be well engaged on the pipe mother or the pipe mother clamp through the cooperation of the bracket body and the elastic contact fingers, thereby ensuring a more fitted contact surface. In cooperation with other contact devices on site, the DC resistance of the main transformer low-voltage side pipe mother can be measured, thereby ensuring the measurement accuracy, facilitating on-site maintenance operations, and reducing the damage to the equipment to be repaired caused by the maintenance operations.

[0043] By adding a spring design, the clamping force is further enhanced. By setting a connecting rod on the bracket body, on-site maintenance work is facilitated, the accuracy of measuring loop resistance data is improved, and the maintenance quality and efficiency are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of the structure of an auxiliary device provided in an embodiment of the present invention;

[0045] Figure 2 A schematic diagram of the structure of an auxiliary device provided in another embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the overall view of the low-voltage side mother tube of the 500kV main transformer;

[0047] Figure 4 It is the contact surface measurement point of position A in the overall diagram of the low-voltage side mother tube of the 500kV main transformer;

[0048] Figure 5 It is the contact surface measurement point of position B in the overall diagram of the mother tube on the low-voltage side of the 500kV main transformer;

[0049] Figure 6 It is the contact surface measurement point of the C position in the overall diagram of the low-voltage side mother tube of the 500kV main transformer;

[0050] Figure 7 It is the contact surface measurement point at position D in the overall diagram of the mother tube on the low-voltage side of the 500kV main transformer;

[0051] Figure 8 An application principle diagram of a specific embodiment of the present invention;

[0052] Fig. 9 This is a schematic diagram of the measurement dimensions of the tube mother and busbar clamp;

[0053] Fig.10 It is a spring working diagram in a specific embodiment;

[0054] In the figure: 1: bracket body; 2: first contact finger; 3: second contact finger; 4: first spring; 5: second spring; 6: connection terminal; 7: operating lever; 8: bending part; 9: connecting piece; 10: serrated surface. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. In order to better understand the technical solution of the present invention, the measurement of the mother tube contact resistance is further introduced below.

[0056] In the description of the present invention, it should be understood that the terms "inside", "outside", "upper layer", "top", "lower layer", "left", "right", "vertical", "horizontal", "parallel", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0057] Figure 3 This is a schematic diagram of the overall view of the low-voltage side of the 500kV main transformer of a 500kV substation. Figure 4-Figure 7 Shows Figure 3 The test method and test fixture of the contact resistance of the conductive contact surface of 4 different types of clamps and wire clamps (A to D), that is, the clamping position of the measuring fixture. Figure 4 The measurement points of part A are shown in the figure: the tube clamp (point g) - the double-row wire clamp (point s). The clamp at point g needs to be clamped on the outer edge of the tube clamp. Figure 5 The measurement points of part B are shown in the figure: the tube mother (point m) - the tube mother clamp (point g). Figure 6 The measurement points of part C are shown in the figure: the mother tube (point m) - the mother coupling clamp (point x). Figure 7 The measurement points of position D are shown in the figure: pipe mother (point m) - single-line clamp (point d).

[0058] The present invention is directed to Figure 4 Middle tube female clamp (g-spot), Figure 5 Middle tube mother (point m), Figure 6 The middle mother tube (point m) and the mother tube (point m) provide an auxiliary device for measuring the DC resistance of the reactive mother tube on the low-voltage side of the main transformer, that is, a measuring fixture.

[0059] The following are specific embodiments.

[0060] Embodiment 1: A device for measuring the DC resistance of reactive power tube mother on the low voltage side of a main transformer, such as Figure 1 As shown, it includes a bracket body 1, the bracket body 1 is a U-shaped opening, and a first contact finger 2 and a second contact finger 3 are respectively arranged on the concave surface of the U-shaped opening of the bracket body 1, the first contact finger 2 and the second contact finger 3 are respectively arranged on the left and right sides of the bracket body 1 and fixed on the bracket body 1; the first contact finger 2 and the second contact finger 3 are both elastic and arc-shaped, and the arc-shaped concave surfaces of the first contact finger 2 and the second contact are in the same direction as the concave surface of the bracket body 1; a wiring terminal 6 is arranged on the bracket body 1 relative to the outer side of the concave surface.

[0061] Since the shapes of the mother pipe and the mother pipe clamp are basically the same, both are round tubes, the bracket body 1 in this embodiment is a U-shaped opening, and two elastic contact fingers are installed on both sides of the bracket body 1. Since the contact fingers have a certain elasticity, when the bracket body 1 is engaged with the mother pipe or the mother pipe clamp through the contact fingers, there is a certain margin to ensure a more fitted contact surface, and in conjunction with other contact devices on site, the DC resistance of the reactive mother pipe on the low-voltage side of the main transformer can be measured, which ensures the accuracy of the measurement, facilitates on-site maintenance operations, and reduces the damage to the equipment to be repaired by maintenance operations. The opening size of the clamp can be designed by a technician in this field according to actual conditions. When in use, the test line is connected through the terminal 6.

[0062] Since the fixture needs to reach a certain point and has a certain mechanical strength, and also needs to take into account the requirement of "light weight", the bracket body 1 and the contact finger can be made of copper or aluminum alloy.

[0063] This embodiment also includes: a first spring 4 is arranged between the first contact finger 2 and the bracket body 1, one end of the first spring 4 is connected to the first contact finger 2, and the other end is connected to the bracket body 1; a second spring 5 is arranged between the second contact finger 3 and the bracket body 1, one end of the second spring 5 is connected to the second contact finger 3, and the other end is connected to the bracket body 1, and the first spring 4 and the second spring 5 correspond in position.

[0064] This embodiment ensures a certain finger pressure by setting a spring, so that the auxiliary device can be well engaged on the pipe mother or the pipe mother clamp, and the torsion spring is used as the working spring according to the test principle of the clamp. Preferably, general purpose carbon steel wire is selected.

[0065] Embodiment 2: Based on the above embodiment, one end of the U-shaped opening of the bracket body 1 in this embodiment is connected to an operating rod 7. Adding the operating rod 7 facilitates the site, improves the accuracy of measuring loop resistance data, and improves the quality and efficiency of maintenance.

[0066] Optionally, the support body 1 includes a left support and a right support (such as Figure 2 As shown), the left bracket and the right bracket are connected and fixed by a connecting member 9. Optionally, the left bracket and the right bracket are riveted on the connecting member 9.

[0067] Optionally, one end of the U-shaped opening of the bracket body 1 further includes a bending portion 8, and the bending portion 8 is an integral structure with the bracket body 1. By providing the bending portion 8, it is convenient for the bracket body 1 to be snapped into the tube mother or the tube mother clamp. Figure 2 As shown, in the specific embodiment, one end of the U-shaped opening of the bracket body 1 is connected to the operating rod 7, and the other end of the U-shaped opening is provided with a bending portion 8.

[0068] Optionally, the first contact finger 2 and the second contact finger 3 are riveted to the bracket body 1 by rivets.

[0069] Optionally, the first spring 4 and the second spring 5 are riveted to the bracket body 1 by rivets.

[0070] In order to further improve the friction between the first contact finger 2 and the second contact finger 3 and the tube mother or the tube mother clamp, in the specific embodiment, the inner concave surfaces of the first spring 4 and the second spring 5 are both provided with serrated surfaces 10.

[0071] The present invention provides a main transformer low-voltage side reactive bus DC resistance measurement auxiliary device, and the application method is as follows: The application method is as follows: When measuring reactive loop resistance, it is necessary to prepare a loop resistance meter, two groups of test wires, two main transformer low-voltage side reactive bus DC resistance measurement auxiliary devices (whose functions are the same as bus clamps or bus clamps), and a power cord reel. Connect the two groups of test wires to the main transformer low-voltage side reactive bus DC resistance measurement auxiliary devices respectively, and two people cooperate to operate and hang the two bus clamps at the measured position, such as Figure 8 The auxiliary device for measuring the DC resistance of reactive mother pipe on the low voltage side of the main transformer provided by the present invention can be well engaged on the mother pipe or the mother pipe clamp through the cooperation of the bracket body 1 and the elastic contact finger, ensuring a more fitted contact surface, and can realize the measurement of the DC resistance of reactive mother pipe on the low voltage side of the main transformer in cooperation with other contact devices on site, thereby ensuring the measurement accuracy, facilitating on-site maintenance operations, and reducing the damage of maintenance operations to the equipment to be repaired.

[0072] By adding a spring design, the clamping force is further enhanced, and by arranging a connecting rod on the bracket body 1, on-site maintenance operations are facilitated, the accuracy of measuring loop resistance data is improved, and the maintenance quality and efficiency are improved.

[0073] When designing the test fixture (i.e., the auxiliary device for measuring the DC resistance of the reactive power bus on the low-voltage side of the main transformer), it is necessary to have a detailed understanding of the relevant dimensions of the test object. For this purpose, the relevant dimensions were tested on-site using the bus power outage opportunity (the units used in this article are all mm).

[0074] 1) Measure the circumference of the tube: C = 550mm, calculate the diameter Φ = about 175mm, see Fig. 9 .

[0075] 2) Measure the circumference of the busbar clamp: C = 780mm, calculate the diameter Φ = about 248mm, width 190mm, see Fig. 9 .

[0076] Embodiment 3. A parameter calculation method for a main transformer low-voltage side reactive main DC resistance measurement auxiliary device, wherein the auxiliary device adopts the device provided in the above embodiment, and the parameter calculation method comprises:

[0077] According to the measured data (such as Fig. 9 ), the diameter of the mother tube is Φ175, the outer diameter of the busbar clamp is Φ248, and the design measurement range is Φ175~Φ248. Now there is a certain margin, and it is designed according to Φ160~Φ260, that is, the measurement range is suitable for mother tubes and clamps of Φ160~Φ260.

[0078] according to Figure 1For the structural type, the compression of the finger springs on both sides must be greater than 50mm. If the spring is designed according to the minimum tube mother diameter Φ160 and a certain finger pressure is guaranteed, when measuring the maximum tube mother diameter Φ260, the compression of the single-side spring will exceed 50mm, and its finger pressure will be hundreds of Newtons. The high pressure will make it difficult to operate and cause measurement failure.

[0079] Based on the above considerations, the opening size of the clamp is divided into two grades: Φ160~Φ200 and Φ200~260. The following is only the design description based on the Φ160~Φ200 grade.

[0080] (I) Selection of materials

[0081] This fixture needs to be conductive and have a certain mechanical strength, while also taking into account the requirement of "light weight". First, the relevant materials are listed in Table 1 for comparison.

[0082] According to the parameters listed in Table 1, considering the strength, conductivity, hardness and weight, 2 series and 7 series aluminum alloys are more suitable.

[0083] Table 1 Comparison of performance parameters of several materials

[0084]

[0085] (ii) Spring design

[0086] The spring is the key component of the fixture. According to the testing principle of the fixture, a torsion spring is selected as the working spring.

[0087] 1) Determination of basic parameters

[0088] (1) Determination of force value

[0089] The diameter of the busbar measured this time is Φ175 and the diameter of the busbar clamp is Φ248. During measurement, the clamping force at the contact point should be no less than 25N. This value should be as large as possible to facilitate the removal of the oxide layer. However, if it is too large, the clamping force will be too large, which is not conducive to operation. Now 28N is selected.

[0090] (2) Torque determination

[0091] According to the dimensions of the fixture, the spring torsion arm is initially determined to be 60. With a double torsion spring structure, the torque borne by each spring is half of the total torque (14×60=840N.mm). Determine the installation torque (preload force) T 1 =300N.mm,

[0092] Working torque T 2 =840N.mm.

[0093] (3) Other parameter requirements

[0094] The spring structure type is NVI single-arm torsion close-rotation right-hand spring, torsion in the forward direction, working torsion deformation angle θ°=θ 2 °-θ 1 °=53°, inner diameter ≥7mm, torsion arm length is 60mm, (the influence of long torsion arm on torsional deformation angle needs to be considered), this structure requires compact size. Fatigue life N>100,000 times.

[0095] 2) Select materials

[0096] According to the actual service life requirements, select the general purpose carbon steel wire group C. According to the working torque T 2 =840N·mm, assuming that the material diameter d = 1.8mm ~ 2.2mm. Check the relevant manual to get the material elastic modulus E = 206×10 3 MP a , the material tensile strength R is obtained from the relevant manual m =1760MP a ~1660MP a , take R m =1710MP a .

[0097] 3) Select the allowable bending stress of the spring

[0098] The spring is subjected to dynamic loading according to the cyclic characteristic γ:

[0099]

[0100] In the manual, γ = 0.35 and 10 7 The ordinate of the intersection of the lines is approximately 0.57, so the allowable bending stress is

[0101] [σ]=0.57R m =0.57×1710=974.7MP a

[0102] 4) Wire diameter

[0103] Calculate the wire material diameter according to the formula, take K b =1

[0104]

[0105] Taking d = 2mm is basically consistent with the original hypothesis and conforms to the GB / T1358 series value. m =1710MP a , [σ] = 0.57R m =0.57×1710=974.7MP a

[0106] 5) Spring diameter

[0107] The inner diameter of the spring is D 1 =7mm, then D 2 =D 1 +2d=7+2×2=11mm

[0108] Spring middle diameter: D = D 1 +d=7+2=9mm

[0109] Convolution ratio C:

[0110] 6) Spring stiffness and torsional deformation angle

[0111] Calculate by formula

[0112]

[0113] Calculate by formula

[0114]

[0115]

[0116] 7) Number of effective spring turns

[0117] Considering the influence of the long torsion arm on the torque deformation angle, the formula is used to calculate

[0118]

[0119] Take n = 9 turns

[0120] 8) According to the test bending stress σ s =0.78R m =0.78×1710=1334MP a , then the test torque T s And the change angle θ under the test torque s °Calculation:

[0121]

[0122]

[0123]

[0124] Then 0.2θ s °≤θ 1 , 2 °≤0.8θ s °, meet the characteristic requirements.

[0125] 9) Guide rod diameter

[0126] Calculate the guide rod diameter D′ according to the formula:

[0127]

[0128] D′=0.9(D 1 -ΔD s )=0.9(7-0.29)=6.04mm

[0129] Take the guide rod diameter D′=6mm.

[0130] 10) Fatigue strength verification

[0131] Calculated by the formula, take K b =1, we get:

[0132]

[0133]

[0134] thereby Among them, 0.11 is the ratio of the minimum stress of the spring when in use to the allowable stress of the material selected for the spring. 0.31 is the ratio of the maximum stress of the spring when in use to the allowable stress of the material selected for the spring.

[0135] A ratio less than 1 indicates that the stress of the spring during use is less than the allowable stress of the material selected for the spring, and the fatigue life of the spring is longer.

[0136] The curve in the manual is a test (verification) curve. The calculated value falls within a certain area, indicating that the fatigue life meets the corresponding value in the area.

[0137] According to the curve in the manual, it can be seen that the point (0.11, 0.31) is between γ = 0.35 and 10 6 Below the intersection of the lines of action, it indicates that the fatigue life of this spring is N>100,000 times.

[0138] 11) Free length and spring expansion length

[0139] The free length is calculated according to the formula:

[0140] H 0 = (nt + d) + length of the torsion arm on the axis = (9 × 2 + 4) + (6 × 2-4) = 30 mm The unfolded length of the spring is calculated according to the formula:

[0141] L≈πDn+torsion arm length=3.14×9×9+(60+30+12)=356.34mm

[0142] 12) Spring working diagram Spring working diagram see Fig.10 , the technical requirements in the figure are:

[0143] a. Spring end structure type: NVI single-arm bending torsion spring;

[0144] b. Rotation direction: right-handed;

[0145] c. Effective number of turns: n = 9 turns;

[0146] d. Surface treatment: apply anti-rust paint;

[0147] e. Manufacturing technical conditions: The rest shall be in accordance with GB / T 1239.3 second level precision.

[0148] 13) Spring parameter table is shown in Table 2.

[0149] Table 2 Design parameters of spring

[0150]

[0151] The present invention analyzes the conductive contact surface structure type of the primary equipment within the jurisdiction, and the method of measuring and processing the contact resistance. The present invention will study the working conditions of measuring resistance, design and process the contact surface resistance fixture for measuring the busbar or busbar clamp. The successful development of the device will effectively solve the difficulties on site, facilitate on-site maintenance work, reduce the damage of maintenance work to the equipment to be repaired, improve the accuracy of the measured loop resistance data, and improve the quality and efficiency of maintenance. The successful development of the device can not only solve the measurement of the reactive circuit mother and clamp on the low-voltage side of the 500kV main transformer, but can also be promoted to the measurement of the DC resistance of the clamp of the 220kV and 110kV open-type mother.

[0152] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Auxiliary device for measuring DC resistance of main transformer low voltage side pipe mother, characterized in that: include A bracket body, wherein the bracket body is a U-shaped opening, and a first contact finger and a second contact finger are respectively arranged on the concave surface of the U-shaped opening of the bracket body, and the first contact finger and the second contact finger are respectively arranged on the left and right sides of the concave surface of the bracket body and fixed on the bracket body; the first contact finger and the second contact finger are both elastic and arc-shaped, and the arc-shaped concave surfaces of the first contact finger and the second contact finger are in the same direction as the concave surface of the bracket body; a wiring terminal is arranged on the bracket body relative to the outer side of the concave surface; a first spring is arranged between the first contact finger and the bracket body, one end of the first spring is connected to the first contact finger, and the other end is connected to the bracket body; a second spring is arranged between the second contact finger and the bracket body, one end of the second spring is connected to the second contact finger, and the other end is connected to the bracket body, and the first spring and the second spring are in corresponding positions; One end of the U-shaped opening of the bracket body further includes a bending portion, and the bending portion and the bracket body are an integral structure.

2. The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother according to claim 1, characterized in that: One end of the U-shaped opening of the bracket body is connected to the operating rod.

3. The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother according to claim 1 is characterized in that: The bracket body comprises a left bracket and a right bracket, and the left bracket and the right bracket are connected and fixed by a connecting piece.

4. The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother according to claim 1 is characterized in that: The first contact finger and the second contact finger are riveted to the bracket body by rivets.

5. The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother according to claim 1 is characterized in that: The inner concave surfaces of the first contact finger and the second contact finger are both provided with serrated surfaces.

6. The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother according to claim 1 is characterized in that: The first spring and the second spring are riveted to the bracket body by rivets.

7. The parameter calculation method of the auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother is characterized in that: The auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother is a device as described in any one of claims 1 to 6, and the parameter calculation method includes: the size of the U-shaped opening of the device is divided into two levels: Φ160~Φ200 and Φ200~260.

8. The parameter calculation method of the main transformer low-voltage side mother DC resistance measurement auxiliary device according to claim 7 is characterized in that: A torsion spring is selected as the first spring and the second spring. The parameters of the first spring and the second spring are determined as follows: (1) Determine the force parameters: Determine the clamping force at the contact point based on the diameter of the tube mother and the diameter of the tube mother clamp; (2) Determine the torque parameters: Based on the dimensions of the device, preliminarily determine the torsion arm of the spring. If a double torsion spring structure is used, the torque borne by each spring is half of the total torque. Determine the installation torque T1 and the working torque T2. (3) Determine other parameter requirements, including: determine the material according to the actual service life requirements; Determine the allowable bending stress of the selected spring by calculating the cyclic characteristic γ, expressed as: , determine the loop characteristic γ and 10 in the manual 7 The ordinate of the intersection point of the lines is determined by the relationship between the ordinate and the tensile strength R of the material. m The product of determines the allowable bending stress [σ] of the spring; calculates the diameter d of the steel wire material, Where T is the torque of each spring, is the intermediate variable, Determine the winding ratio C based on the spring inner diameter D1 and the wire material diameter d, the formula is as follows: ， Where D is the spring median diameter: D=D1+d; Calculate the spring rate using the following formula and torsional deformation angle and : ， ， ， The following formula is used to calculate the effective number of spring turns n: ， E is the elastic modulus of the material; l1 is the length of the torsion arm on one side of the torsion spring; l2 is the length of the torsion arm on the other side of the torsion spring; According to the test bending stress σ s , then the test torque T s And the change angle under the test torque The calculation formula is as follows: ， ， is the spring diameter; n is the effective number of coils of the spring, Calculate the guide rod diameter D', the formula is as follows: , ， Calculate the free length H0 using the following formula: H0=(nt+d)+L0, L0 is the length of the torsion arm on the axis, n is the effective number of coils of the spring; t is the spring pitch, Calculate the spring expansion length L, the formula is: L≈πDn+ L1, L1 is the torsion arm length.

9. According to the parameter calculation method of the auxiliary device for measuring the DC resistance of the main transformer low-voltage side pipe mother according to claim 8, the fatigue life of the spring is determined as follows: ， ， in, Maximum allowable bending stress in the spring, The minimum allowable bending stress of the spring is used to determine the ratio of the maximum allowable bending stress of the spring to the allowable stress of the material selected for the spring, as well as the ratio of the minimum allowable bending stress of the spring to the allowable stress of the material selected for the spring. The fatigue life of the spring is determined based on the comparison results.

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