CN104882764B - A kind of method for reducing transmission facility contact gold utensil contact heating - Google Patents
A kind of method for reducing transmission facility contact gold utensil contact heating Download PDFInfo
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- CN104882764B CN104882764B CN201510180554.9A CN201510180554A CN104882764B CN 104882764 B CN104882764 B CN 104882764B CN 201510180554 A CN201510180554 A CN 201510180554A CN 104882764 B CN104882764 B CN 104882764B
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- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000010438 heat treatment Methods 0.000 title claims abstract description 23
- 230000005540 biological transmission Effects 0.000 title claims abstract description 14
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 title abstract description 9
- 239000010931 gold Substances 0.000 title abstract description 9
- 229910052737 gold Inorganic materials 0.000 title abstract description 9
- 238000012360 testing method Methods 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims description 34
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 13
- 229910052802 copper Inorganic materials 0.000 claims description 13
- 239000010949 copper Substances 0.000 claims description 13
- 238000009434 installation Methods 0.000 claims description 12
- 229910052782 aluminium Inorganic materials 0.000 claims description 11
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 11
- 230000006835 compression Effects 0.000 claims description 11
- 238000007906 compression Methods 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 238000013461 design Methods 0.000 claims description 9
- 230000020169 heat generation Effects 0.000 claims description 6
- 238000004364 calculation method Methods 0.000 claims description 4
- 238000005259 measurement Methods 0.000 claims description 4
- 238000012935 Averaging Methods 0.000 claims description 2
- 238000009826 distribution Methods 0.000 abstract description 3
- 238000009413 insulation Methods 0.000 abstract description 3
- 230000015556 catabolic process Effects 0.000 abstract 1
- 239000004020 conductor Substances 0.000 description 15
- 239000010408 film Substances 0.000 description 12
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 238000003825 pressing Methods 0.000 description 5
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 238000013021 overheating Methods 0.000 description 4
- 230000017525 heat dissipation Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000005489 elastic deformation Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 230000013011 mating Effects 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000007431 microscopic evaluation Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000010301 surface-oxidation reaction Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Gasket Seals (AREA)
- Preventing Corrosion Or Incrustation Of Metals (AREA)
Abstract
The present invention provides a kind of method for reducing transmission facility contact gold utensil contact heating, and its step is as follows：Contact gold utensil contact mechanical property test block is made, the yield strength of test block is tested；Calculate fastening bolt pretightning force, the prefastened moment of torsion of fastening bolt is calculated by fastening bolt pretightning force again, finally, adjust with the torque value of torque wrench to the prefastened moment of torsion of fastening bolt, again with torque wrench securable fastener nut, the stopping fastening when torque wrench sends alarm, the connection fastening of electrical contact gold utensil contact is completed.To solve the existing contact of contact gold utensil at this stage when in use, contact resistance is larger between contact, easily there is superheating phenomenon, contact situations such as insulation breakdown occur, burn fracture that be badly damaged in a short time can be caused to cause accident and interruption of power supply when serious, have a strong impact on the problem of distribution safety.The invention belongs to technical field of electric power transmission.
Description
Technical Field
The invention relates to a connection fastening method for reducing heating of an electrical contact hardware fitting contact, and belongs to the technical field of power transmission.
Background
The electric contact hardware fitting in the power system is used for connecting a hard bus and a soft bus with an outlet terminal of electric equipment, T connection of a lead, parallel connection without bearing force and the like. The contact hardware fitting contact is a contact connection part of two conductors or a plurality of conductors, such as a bus or a lead, the contact plate of the electrical contact hardware fitting is usually a flat plate, a bolt hole is processed on the contact plate, the contact hardware fitting contact generally comprises an inflow contact hardware fitting and an outflow contact hardware fitting, and the inflow contact hardware fitting contact plate and the outflow contact hardware fitting contact plate are connected by a fastening bolt. The typical structure is shown in figure 1.
The heating of the electric contact hardware contact during normal operation is related to the contact resistance value, so the quality of the contact depends on the contact resistance value of the contact to a great extent. Normally, contact pressure between contacts, surface processing conditions, surface oxidation degree, contact conditions and the like affect contact resistance.
1 contact resistance of electric contact hardware contact
Electrical contact is the study of mechanical phenomena in solid-state conductors and in the contact transition region of solid-state conductors. There are three types of electrical contacts: point contact, line contact and surface contact, and the influence of the contact form on the contact resistance is mainly reflected on the number of contact points. Generally, the contact resistance decreases as the number n of contact points of the surface contact increases. The smaller the number of contact points n of the point contact, the larger the contact resistance, and the line contact is interposed therebetween.
The surface of the contact fitting contact was observed under a microscope, and the convex portion of 5 to 10 μm was observed although the surface was very smooth. It will be seen that the contact of the mating pair of contacts is not the contact of the entire contact surface, but is spread over the contact surface at points of contact. The actual contact surface is necessarily smaller than the theoretical contact surface. The difference between the two can reach thousands of times according to the surface smoothness and the contact pressure. The actual contact surface can be divided into two parts; one is the real metal-to-metal direct contact portion. I.e., contact micro-points with no transition resistance between metals, also known as contact patches, which are formed after the interfacial film is damaged by contact pressure or heat. The portion occupies about 5-10% of the actual contact area. The second is the parts which are contacted with each other after the film is polluted through the contact interface. Since any metal has a tendency to return to the oxide state. In fact, there is no truly clean metal surface in the atmosphere, even a very clean metal surface, once exposed to the atmosphere, will soon develop an initial oxide film layer of several microns. For example, copper can be formed in 2-3 minutes, nickel can be formed in about 30 minutes, and aluminum can be formed in about 2-3 seconds, and an oxide film with a thickness of about 2 microns can be formed on the surface of the copper. Even if the noble metal gold is particularly stable, an organic gas adsorption film is formed on the surface of the gold due to its high surface energy. In addition, dust and the like in the atmosphere also form a deposited film on the surface of the contact. Thus, any contact surface is a contaminated surface from microscopic analysis.
For a contact hardware contact, the conductor resistance is relatively small, and the contact resistance is greatly influenced by the material, contact pressure, contact area and the like of the contact surface. According to the current line shrinkage and the contact spot condition, most of the contact surface is a gap, the gap does not participate in actual contact, and only part of the peak points of the profile are actually contacted to form the conductive spot. When the current line passes through the vicinity of the conductive spot, heat energy is generated to shrink, so that the path through which the current flows is increased, the effective conductive area is reduced, and thus, the shrinkage resistance is generated. Under the action of external contact force, the area of the element which is actually contacted is very small, and the initial contact point firstly generates elastic deformation and then transits to plastic deformation. The contact process is ended when the total actual contact area is enlarged to a point where the support force is balanced with the external force.
In summary, the true contact resistance should be composed of the following parts:
(1) centralized resistor
When current passes through the actual contact surface, the resistance is shown due to the contraction (or concentration) of the current lines. It is referred to as a lumped resistance or a pinch resistance.
(2) Film resistor
Due to the film resistance formed by the contact surface film and other contaminants. From the contact surface state analysis, the surface contamination film can be divided into a firmer thin film layer and a looser impurity contamination layer. Therefore, the film resistance can be also called an interface resistance.
(3) Conductor resistor
The actual measurement of the contact resistance of the contact hardware fitting contact is carried out at the contact leading-out end, so the actually measured contact resistance also comprises the conductor resistance of a contact piece and a leading-out wire per se outside the contact surface. The resistance of a conductor depends mainly on the electrical conductivity of the metal material itself, and its relationship with the ambient temperature can be characterized by a temperature coefficient.
For the sake of distinction, the collective resistance plus the film resistance is referred to as the true contact resistance. And the actual measured value including the conductor resistance is referred to as the total contact resistance.
2 factors influencing contact resistance of contact of electric contact fitting
The contact resistance of the electrical contact fitting contact is formed by the contact surface contact of two conductors which form the electrical contact, and depends on the current carrying area of the two conductors in direct contact, the pressure applied to the contact surface and the corrosion degree of the contact surface.
Through analysis, the following four major factors influencing the contact resistance should be considered when designing, manufacturing and installing the electrical contact fitting contact.
(1) The effective current-carrying cross-sectional area of the electrical contact hardware contact.
The effective current-carrying sectional area refers to a contact area which is in contact with the hardware contact under the action of sufficient pressure. The current carrying capacity of a conductor is closely related to the cross-sectional area of the conductor, and as a current-conducting electrical contact, the current carrying capacity without overheating also depends on the current carrying cross-sectional area.
(2) And electrically contacting the pressure of the hardware contact.
The contact surface of the contact fitting is not absolutely flat, and is still uneven from a microscopic view, the contact surface can make the uneven surface effectively contact only under the action of enough pressure, otherwise, the pressure is insufficient, and the effective current carrying surface of the contact surface is reduced, so that the contact resistance is increased.
(3) Corrosion protection of electrical contact hardware contacts.
If the contact surface is corroded by thermal oxidation, the resistivity of the contact surface is increased, so that the contact resistance is increased.
(4) The material of the electric contact hardware contact and the fastener is fatigue.
When the contact is heated for a long time in operation, the mechanical strength of the electrical contact and the fastener can be gradually weakened, so that the pressure of a contact surface is reduced, the effective current carrying area is reduced, and the contact resistance is increased.
The contact hardware contact is formed by connecting conductors and plays a role in guiding current, various electrical equipment in an electric power system needs to be connected with the contact hardware contact, but a certain contact resistance exists at the contact hardware contact, a part of electric energy is consumed when current flows through the contact, the part of electric energy is converted into heat energy to cause the contact to generate heat, and the temperature of the contact rises along with the heat energy until the heat generation and the heat dissipation reach balance. The temperature rise of the contact relative to the environment temperature depends on the magnitude of heat productivity and the quality of heat dissipation conditions, under the condition that the heat dissipation conditions are basically consistent, the larger the heat productivity is, the higher the temperature rise is, the more serious the damage of the contact caused by corrosion, material fatigue and the like is, when the temperature of the contact exceeds the highest allowable temperature and is even higher, the overheating condition occurs, and the contact can be seriously damaged in a short time, and the power supply is interrupted due to the conditions of insulation damage, burning fracture and the like.
According to defects statistics of Guizhou power grid companies, 3200 parts of contacts of Guizhou power grid electrical contact hardware in 2014 seriously generate heat, and the safety of a distribution network is seriously influenced. Therefore, researches on measures for reducing the heating of the contact of the power grid contact hardware are urgent and have very important significance.
Disclosure of Invention
The invention aims to: the method for reducing the heating of the contact hardware fitting contact of the power transmission equipment is provided, and the problems that when the contact hardware fitting contact is used at the present stage, the contact indirect electric shock resistance is large, the overheating phenomenon is easy to occur, and the power supply is interrupted and the distribution network safety is seriously influenced due to the fact that the contact is seriously damaged in a short time, the insulation damage occurs, the burning fracture occurs and the like in the serious case are solved.
The scheme of the invention is as follows: a method for reducing the heating of a contact hardware fitting contact of power transmission equipment comprises the following specific steps:
manufacturing a contact hardware fitting contact mechanical property test block, and testing the yield strength of the test block;
calculating the pretightening force of the fastening bolt:
the temperature after installation is t when not put into operation0When the gap between the inflow contact and the outflow contact is α0Thickness of the inflow contact10Is composed of
Thickness of outflow contact20Is composed of
Length l between two washers of bolt0Is composed of
l0＝10+20+α0(3)
The original length of the length between two washers of the bolt after installation, i.e. the free length L is
Wherein,
d1initial thickness of the inflow contact
d2Original thickness of the tap
E1Young's modulus of bolt
E2Young's moduli of inflow and outflow contacts
p-bolt installation stress
m-bolt cross section area
s-contact area of the contact hardware, and taking the area of the compression gasket when the size of the contact area of the contact hardware is larger than that of the compression gasket;
the pressure of the bolt gasket is equal to the elastic force of the contact, and the direction is opposite to that of the contact, namely
Wherein,
delta-operating temperature t1The total elastic length deformation of the inflow contact and the outflow contact is elongated in a positive value and compressed in a negative value;
Δ l-temperature in operation t1The original length of the bolt between the two gaskets is deformed, the positive value is elongated, and the negative value is compressed;
the total thickness of the contact plus the length of the bolt between the two gaskets, including
L+Δl+[(10+20+α0)×(t1-t0)×A1]＝
d1+d2+Δ+(10+20)×(t1-t0)×A2+α0(6)
Wherein,
t0temperature when not in operation after installation
t1For operating temperature, i.e. temperature at the time of measurement
A1Coefficient of linear expansion of the bolt
A2-the linear expansion coefficients of the inflow and outflow contacts;
by the formula (5) and (6), the following can be obtained:
boundary conditions:
1) operating temperature t1In order to design the lowest temperature of the environment, the bolt tension N must be greater than 0, i.e.Nmin>0；
2) Operating temperature t1In order to design the maximum environment temperature, the maximum design environment temperature may have different standards for different enterprises, the Guizhou power grid company uses 70 ℃ as the maximum design environment temperature, generally 70 ℃ or 80 ℃ as the standard, and the contact stress Q of the contact hardware must be smaller than the yield strength sigma of the contact hardwaresI.e. by
The pretightening force of the fastening bolt is represented by the formulas (1), (2), (3), (4), (5), (6), (7) and (8)Deriving boundary conditions, and taking the average value of the lowest temperature allowable value and the highest temperature allowable value to obtain the pretightening force F of the fastening bolt0Comprises the following steps:
calculating the pre-fastening torque of the fastening bolt according to the pre-fastening force of the fastening bolt, wherein the process can be realized by adopting a conventional calculation means in the field;
and then, adjusting the torque value of the torque wrench to the pre-tightening torque of the fastening bolt, tightening the nut of the fastening piece by using the torque wrench, stopping tightening when the torque wrench gives an alarm, and completing the connection and tightening of the electric contact hardware fitting contact.
Preferably, according to the material of the contact, as the heat treatment process of the contact material in the industry is very mature, each contact material is generally processed by adopting one or more corresponding specific heat treatment processes, the contact material of each brand is subjected to heat treatment by using the corresponding heat treatment process of the material to manufacture a contact material mechanical property test block, the hardness and the yield strength of the test block are tested, so that a hardness-yield strength relation curve of the contact material is manufactured, the relation curve is digitized, and a hardness-yield strength relation curve database of the contact material is established;
preferably, the contact material is electrical aluminum or electrical copper;
preferably, the method develops electric contact hardware fitting fastening bolt torque calculation software running in an intelligent terminal, compiles a database of a relationship curve of the hardness in Richardson and yield strength of a contact material, a calculation formula of the pre-tightening force of the fastening bolt and the torque of the fastening bolt and a friction coefficient nesting into the calculation software, when the contact hardware parameters and the fastener parameters are input into the intelligent terminal, the pre-tightening torque of the fastening bolt is automatically calculated, the software can be designed easily on the basis of the prior art, the contact hardware parameters comprise material, contact head hardness and contact area of a contact head plate, the fastener parameters comprise bolt material, nut material, bolt cross section diameter, thread nominal diameter, thread pitch, nut pressing surface diameter or nut opposite side, pressing gasket inner diameter and pressing gasket outer diameter, and the thread pitch is lead for multiple spirals;
preferably, the torque wrench is a digital display torque wrench, and the precision is not less than 0.1 Nm.
Compared with the prior art, the invention has the following advantages: the method can ensure that sufficient pressure exists between the electrical contact contacts, thereby ensuring that the electrical contact contacts have larger effective current-carrying sectional area, the contact resistance of the contact hardware contact is smaller, the calorific value is low during use, overheating is avoided, meanwhile, the thermal oxidation corrosion of the contact surface can be reduced due to low calorific value, the fatigue condition of the contact hardware contact and the material of a fastener is reduced, and the contact resistance of the contact hardware contact is further reduced.
Drawings
Figure 1 is a schematic structural diagram of the connection of an inflow contact fitting contact plate and an outflow contact fitting contact plate,
in the drawings, 1 denotes a hexagon bolt, 2 denotes a hexagon nut, 3 denotes a pressure washer, 4 denotes an inflow contact, and 5 denotes an outflow contact.
Detailed Description
To make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below,
example (b):
referring to fig. 1, the present embodiment provides a method for reducing heat generation of a contact of a power transmission equipment contact fitting,
by using different brands and different processing techniques to manufacture the copper mechanical property test block,
the method comprises the following steps of (1) carrying out heat treatment on each grade of electrical copper by using a corresponding heat treatment process of the electrical copper in the field to manufacture mechanical property test blocks of the electrical copper under different grades and different heat treatment process conditions (namely manufacturing the mechanical property test blocks of the copper by using different grades and different heat treatment processes), testing the hardness and yield strength of the test blocks, manufacturing a relation curve of the hardness-yield strength of the copper, digitalizing the relation curve, and establishing a relation curve database of the hardness-yield strength of the copper;
the method comprises the following steps of (1) carrying out heat treatment on each grade of electrical aluminum by using a corresponding heat treatment process of the electrical aluminum in the field to manufacture mechanical property test blocks of the electrical aluminum under different grades and different heat treatment process conditions (namely manufacturing the mechanical property test blocks of the aluminum by using different grades and different heat treatment processes), testing the hardness and yield strength of the test blocks, manufacturing an aluminum hardness-yield strength relation curve, digitalizing the curve, and establishing an aluminum hardness-yield strength relation curve database;
the electric contact fitting is used for connecting a hard bus and a soft bus in an electric power system with a wire outlet terminal of electric equipment, connecting a lead T and a parallel wire without bearing force, and the like, and is made of copper or aluminum, a contact plate of the electric contact fitting is usually a flat plate, a bolt hole is processed on the contact plate, the contact area of the contact of the electric contact fitting is larger than 3.5 times of the sectional area of a conductor of a transmission lead, parameters of the contact fitting are marked on the fitting, and the parameters of the contact fitting comprise material, contact hardness in Richardson and contact area of the contact plate.
The structure when electric contact gold utensil contact passes through the fastener and connects refers to figure 1, electric contact gold utensil contact fastener includes hex bolts 1, hex nuts 2, pressure pad 3(2 pieces), the hex bolts, the hex nuts is the standard component, pressure pad is made with 1Cr18Ni9Ti stainless steel, pressure pad diameter is greater than hex bolts nominal diameter x 1.625, pressure pad thickness is greater than hex bolts nominal diameter x 0.375, the fastener parameter includes the bolt material, the nut material, bolt cross section diameter, screw thread nominal diameter, screw thread pitch (for the spiral that many spirals are the helical pitch), nut clamping face diameter (or nut opposite side), pressure pad internal diameter, pressure pad external diameter etc. the fastener parameter mark is in the fastener specification.
Calculating the pretightening force of the fastening bolt:
the temperature after installation is t when not put into operation0When the gap between the inflow contact and the outflow contact is α0Thickness of the inflow contact10Is composed of
Thickness of outflow contact20Is composed of
Length l between two washers of bolt0Is composed of
l0＝10+20+α0(3)
The original length of the length between two washers of the bolt after installation, i.e. the free length L is
Wherein,
d1initial thickness of the inflow contact
d2-outflow contactOriginal thickness
E1Young's modulus of bolt
E2Young's moduli of inflow and outflow contacts
p-bolt installation stress
m-bolt cross section area
s-contact area of the contact hardware, and taking the area of the compression gasket when the size of the contact area of the contact hardware is larger than that of the compression gasket;
the pressure of the bolt gasket is equal to the elastic force of the contact, and the direction is opposite to that of the contact, namely
Wherein,
delta-operating temperature t1The total elastic length deformation of the inflow contact and the outflow contact is elongated in a positive value and compressed in a negative value;
Δ l-temperature in operation t1The original length of the bolt between the two gaskets is deformed, the positive value is elongated, and the negative value is compressed;
the total thickness of the contact plus the length of the bolt between the two gaskets, including
L+Δl+[(10+20+α0)×(t1-t0)×A1]＝
d1+d2+Δ+(10+20)×(t1-t0)×A2+α0(6)
Wherein,
t0temperature when not in operation after installation
t1For operating temperature, i.e. temperature at the time of measurement
A1Coefficient of linear expansion of the bolt
A2-the linear expansion coefficients of the inflow and outflow contacts;
by the formula (5) and (6), the following can be obtained:
boundary conditions:
1) operating temperature t1In order to design the lowest temperature of the environment, the bolt tension N must be greater than 0, i.e.Nmin>0；
2) Operating temperature t1In order to design the highest temperature of the environment (taking 70 ℃ as the highest temperature of the design environment as an example), the contact stress Q of the contact hardware needs to be smaller than the contact yield strength sigma of the contact hardwaresI.e. by
The pretightening force of the fastening bolt is derived from formulas (1), (2), (3), (4), (5), (6), (7) and (8) and boundary conditions, and the pretightening force F of the fastening bolt is obtained by averaging the allowable minimum temperature value and the allowable maximum temperature value0Comprises the following steps:
and calculating the pre-tightening torque of the fastening bolt according to the pre-tightening force of the fastening bolt:
the fastening bolt pre-fastening torque was calculated by the following formulas (10), (11), (12), (13), (14) and (15).
F0-tightening bolt pretension
Nominal diameter of d-thread
P-thread pitch (lead for multiple helix)
DwDiameter of nut pressing surface (or nut opposite side)
d2Pitch diameter of the thread
Phi-lead angle
ρvThread equivalent friction angle
Friction factor between mu-nut and supporting surface of connected part (or washer)
μvThread equivalent coefficient of friction
T1Overcoming the thread resistance torque of the thread pair
T2End-face friction torque of nut and support face of connected part (or washer)
T-clamp bolt pre-tightening torque
d2＝d-0.65×P (10)
ρv＝arctgμv(12)
T＝T1+T2(15)
Developing electric contact hardware fitting fastening bolt torque calculation software running on an intelligent terminal of an Android operating system, and embedding a copper Rie hardness-yield strength relation curve database, an aluminum Rie hardness-yield strength relation curve database, fastening bolt pre-tightening force and fastening bolt torque calculation (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) formula and a friction coefficient into the calculation software in a nested manner, wherein when parameters of the contact hardware fitting (the parameters of the contact hardware fitting comprise material, contact Rie hardness and contact plate contact area) and parameters of a fastener (the parameters of the fastener comprise bolt material, nut material, bolt cross section diameter, thread nominal diameter, thread torque (for multiple spirals as lead), nut pressing surface diameter (or nut opposite side) are input into the intelligent terminal, The inner diameter of the compression gasket and the outer diameter of the compression gasket) and then automatically calculate the pre-tightening torque of the fastening bolt.
And then, adjusting the torque value of the torque wrench to the pre-fastening torque of the fastening bolt, fastening the nut of the fastening piece by using the torque wrench, stopping fastening when the torque wrench gives an alarm, completing the connection and fastening of the electric contact hardware fitting contact, and ensuring that the contact is in good contact and does not generate heat after long-term operation.
Claims (5)
1. A method for reducing the heating of a contact hardware fitting contact of power transmission equipment is characterized by comprising the following specific steps:
manufacturing a contact hardware fitting contact mechanical property test block, and testing the yield strength of the test block;
calculating the pretightening force of the fastening bolt:
the temperature after installation is t when not put into operation0When the gap between the inflow contact and the outflow contact is α0Thickness of the inflow contact10Is composed of
Thickness of outflow contact20Is composed of
Length l between two washers of bolt0Is composed of
l0＝10+20+α0(3)
The original length of the length between two washers of the bolt after installation, i.e. the free length L is
Wherein,
d1initial thickness of the inflow contact
d2Original thickness of the tap
E1Young's modulus of bolt
E2Young's moduli of inflow and outflow contacts
p-bolt installation stress
m-bolt cross section area
s-contact area of the contact hardware, and taking the area of the compression gasket when the size of the contact area of the contact hardware is larger than that of the compression gasket;
the pressure of the bolt gasket is equal to the elastic force of the contact, and the direction is opposite to that of the contact, namely
Wherein,
delta-operating temperature t1The total elastic length deformation of the inflow contact and the outflow contact is elongated in a positive value and compressed in a negative value;
Δ l-temperature in operation t1The original length of the bolt between the two gaskets is deformed, the positive value is elongated, and the negative value is compressed;
the total thickness of the contact plus the length of the bolt between the two gaskets, including
Wherein,
t0temperature when not in operation after installation
t1For operating temperature, i.e. temperature at the time of measurement
A1Coefficient of linear expansion of the bolt
A2-the linear expansion coefficients of the inflow and outflow contacts;
by the formula (5) and (6), the following can be obtained:
boundary conditions:
1) operating temperature t1In order to design the lowest temperature of the environment, the bolt tension N must be greater than 0, i.e.
Nmin>0；
2) Operating temperature t1In order to design the highest temperature of the environment, the contact stress Q of the contact hardware must be smaller than the yield strength sigma of the contact hardwaresI.e. by
The pretightening force of the fastening bolt is derived from formulas (1), (2), (3), (4), (5), (6), (7) and (8) and boundary conditions, and the pretightening force F of the fastening bolt is obtained by averaging the allowable minimum temperature value and the allowable maximum temperature value0Comprises the following steps:
calculating the pre-tightening torque of the fastening bolt according to the pre-tightening force of the fastening bolt;
and then, adjusting the torque value of the torque wrench to the pre-tightening torque of the fastening bolt, tightening the nut of the fastening piece by using the torque wrench, stopping tightening when the torque wrench gives an alarm, and completing the connection and tightening of the electric contact hardware fitting contact.
2. The method for reducing the heat generation of the contact fitting contact of the power transmission equipment according to claim 1, wherein the method comprises the following steps: according to the material of the contact, after the contact material of each brand is subjected to heat treatment by using the corresponding heat treatment process of the material, a contact material mechanical property test block is manufactured, the hardness and the yield strength of the test block are tested, so that a hardness-yield strength relation curve of the contact material is manufactured, the relation curve is digitized, and a hardness-yield strength relation curve database of the contact material is established.
3. The method for reducing the heat generation of the contact fitting contact of the power transmission equipment according to claim 1 or 2, wherein the method comprises the following steps: the contact material is electrical aluminum or electrical copper.
4. The method for reducing the heat generation of the contact fitting contact of the power transmission equipment according to claim 2, wherein the method comprises the following steps: the method comprises the steps of developing electric contact hardware fitting fastening bolt torque calculation software running on an intelligent terminal, programming a database of a hardness-yield strength relation curve of a contact material, a calculation formula of a fastening bolt pretightening force and a fastening bolt torque, and a friction coefficient nesting into the calculation software, automatically calculating the fastening bolt pretightening torque after inputting contact hardware fitting parameters and fastener parameters of the intelligent terminal, wherein the contact hardware fitting parameters comprise material, contact hardness and contact plate contact area, the fastener parameters comprise bolt material, nut material, bolt cross section diameter, thread nominal diameter, thread pitch, nut compression surface diameter or nut opposite side, compression gasket inner diameter and compression gasket outer diameter, and the thread pitch is lead for multiple spirals.
5. The method for reducing the heat generation of the contact fitting contact of the power transmission equipment according to claim 1, 2 or 4, wherein the method comprises the following steps: the torque wrench is a digital display torque wrench, and the precision is not less than 0.1 Nm.
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| CN201510180554.9A CN104882764B (en) | 2015-04-16 | 2015-04-16 | A kind of method for reducing transmission facility contact gold utensil contact heating |
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| CN201510180554.9A CN104882764B (en) | 2015-04-16 | 2015-04-16 | A kind of method for reducing transmission facility contact gold utensil contact heating |
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| CN104882764B true CN104882764B (en) | 2017-06-30 |
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| CN103335825B (en) * | 2013-05-14 | 2016-11-23 | 国家电网公司 | A kind of Bolt Tightening Force coefficient measuring method |
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