Wire Sag Research Articles

Magnetic integrals minimization methods for superconducting insertion devices

Stretched wire with direct current magnetic measurements method is used for producing synchrotron radiation generation insertion devices. The method allows to measure and to minimize the first and the second magnetic field integrals. The paper focuses on the wire sag problem.

Static and Dynamic Analysis of Conductor Rail with Large Cross-Sectional Moment of Inertia in Rigid Catenary Systems

The rigid catenary system is widely used in tunnels to power electric trains via contact with a pantograph. Due to gravity, the contact wire normally has a sag that may affect the dynamic interaction performance with a pantograph. To reduce the contact wire sag, the most efficient measure is to improve the moment of inertia of the conductor rail, which is used to clamp the contact wire. Six new types of conductor rail with large moments of inertia are developed based on a conventional conductor rail. Then both the static and dynamic analyses are conducted to investigate the performance of the new types of conductor rail with a big moment of inertia. The conductor rail’s 3D solid finite element model is built using a finite element approach. The vertical deflection and the stress distribution are comparatively analyzed among different types of conductor rail. The analysis results indicate that the vertical deflection and maximum stress are significantly reduced when using the conductor rail with a large moment of inertia. The best performance is observed when the conductor rail of case 1 is used. The maximum sag is reduced by 28.37%, and the maximum stress is decreased by 27.76% compared with the conventional conductor. Finally, a pantograph model is included to evaluate the dynamic performance of the conductor rail with large moments of inertia. The results indicate that contact force fluctuation is significantly reduced after the conductor rails with large moments of inertia are presented. The conductor rail of case 1 shows the best performance, which can reduce the contact force standard deviation by 32% and 27% at speeds of 160 km/h and 200 km/h.

Математическая модель модуля дистанционного мониторинга проводов по каналу измерения температуры провода воздушной линии

In continuation of the previously published research results (Energy Safety and Energy Economy, iss. 2, 2021), we have developed wire temperature-based mathematical models for overhead power line monitoring. Mathematical models simulate allowable amperage load considering the temperature and an allowable wire sag considering the temperature and amperage. The proposed mathematical models became a base for overhead power line remote control tools being currently tested at power utility companies.

Устройство бесконтактного измерения гололедной массы на проводах воздушных линий электропередачи

Ice buildup monitoring is essential to prevent wire breakage on overhead power lines. Conventional telemetry systems which are based on load cell sensors have some drawbacks as reflected in this paper. We suggest an innovative device for contactless ice buildup monitoring of overhead power line wires video recording the power line clearance. A specific algorithm for detecting the lowest point of wire sag has been provided. Also, we analyze a possibility of indirect contact sensor-free measurements of a wire temperature when the wire is being covered by icy deposits. A specific buildup type can be determined comparing a dew point and desublimation point as shown in this paper.

Magnet alignment monitoring system with eigenfrequency-based wire sag correction

The precision of magnet alignment in next-generation light sources is critical. To achieve this, the multipole magnets on a common girder of SPring-8-II, an upgrade of SPring-8, are planned to be aligned using the vibrating-wire technique. We developed an alignment monitoring system to monitor the magnet positions in the tunnel where the vibrating-wire technique cannot be executed while the magnets are not energized or when there are vacuum chambers in the magnet center. The alignment monitoring system utilizes a non-contact capacitive sensor embedded in a ceramic ball to measure the wire position relative to the center of the ball and derives the wire sag by measuring a higher mode eigenfrequency. The constitution of this system is illustrated for relevant studies, including the investigation of wire sag against the eigenfrequency, observation of the actual wire sag at a test bench, and validation of the system on the girders for the prototype magnets of SPring-8-II. The system measured the positions of a series of magnets with a precision of ±4 µm (peak to peak) in a 4 m range, in both the horizontal and vertical directions, meeting the requirement of SPring-8-II.

Monitoring of ice formation of overhead power line wires

Reliable operation of electric power systems is impossible without the creation of modern monitoring devices that control all processes of production and distribution of electric energy. The authors of the article developed an intelligent system for monitoring ice formation and determining the wire sag boom using machine vision technology. The monitoring system under consideration is placed on a support in close proximity to the wire and consists of the following main elements: an electronic unit, an optical sensor, a solar panel and a GSM antenna. The developed monitoring system in close proximity to the thickness of the ice wall and indirectly, by the angle of deviation of the wire relative to the horizontal position, to determine the mass of ice deposits and the arrow of the wire sag.

Overhead Transmission Line Sag Estimation Using the Simple Opto-Mechanical System with Fiber Bragg Gratings-Part 2: Interrogation System.

This article presents the use of a sensor with fiber Bragg grating along with an interrogation system used for monitoring the overhead lines’ wire elongation. The possible interrogation methods based on adjusted filters were considered. In the experimental part, three types of fiber Bragg grating pairs, characterized by a small shift in spectra in pairs and gratings with exact matching, were examined. The study showed that, by choosing the appropriate mechanical parameters of the elongation transformer with the optical parameters of the sensor and dedicated filter, the optomechanical system can be adjusted to the required range of overhead line wire sag observation. The range of sag depends on the distance between the poles, the wire type, and its real length in the span, which effectively determines the sag.

Mechanical Calculation of Flexible Wires Loaded with Concentrated Loads

Calculating of wires sag and tension under various modes is the task of mechanical calculation. The article derived formulas for the curve of the wire sag under the action of one or several concentrated forces and with various tensioning insulators strings in the span. Formulas for estimating the distance to the maximum sag have been obtained. Based on the length of the system of “first tension insulators string – conductors – second tension insulators string” that depends on the supporting beam reactions and beam lateral forces in the corresponding sections, the system load factor was determined taking into account structural elements for different climatic loads. The formulas to calculate the load factor for solving the equation of state in the case of different insulators strings in span loaded with one or several concentrated forces have been obtained. The resulting expressions can also be applied in case of horizontal wind loads; in this case the equation of state should take this component into account when calculating the resulting reduced load on the wire in an inclined plane. The reliability of the formulas was proved by the coincidence of the results for the particular case of the arrangement of the insulators strings. An algorithm for calculating sag under the combined action of vertical and horizontal loads, as well as in the case of the location of wire suspension points at different heights, is given. A formula has been proposed for estimating the sag increase factor due to the presence of concentrated forces uniformly distributed along the span and various insulator strings in the span. The dependence of the coefficient of increase of the sag on the distance to the concentrated force in the presence of one and two forces in the span is drawn.

Система мониторинга интенсивности гололедообразования на проводах воздушной линии электропередачи

Improving the reliability and efficiency of power supplying by reducing accidents in electrical networks caused by intense ice and wind loads is an important comprehensive task. The solution of this problem consists of several mainly stages: timely detection of the onset of ice formation, impact on the device for removing ice and frost deposits and efficiency of removing of ice monitoring. This article discusses a system for detecting ice formation based on a fundamentally new technique using the technology of «machine vision». The developed system of ice formation makes identify the thickness of ice wall and indirectly, by the angle of deviation of the wire relative to the horizontal position, to determine the mass of ice deposits and wire sag. Considered monitoring system is located on support in close proximity from the wire and consists of the following mainly elements: an electronic unit, an optical sensor, a solar panel and GSM antenna

Performance verification of a precise vibrating-wire magnet alignment technique for next-generation light sources.

The high-accuracy alignment of magnets is a key issue in the development of next-generation light-source rings. To obtain adequate dynamic apertures, the magnets must be aligned to an accuracy of 10 µm or better. Recently, a new technique that utilizes a vibrating wire has attracted attention for this purpose as it can directly determine with high resolution the magnetic centers in a series of multipole magnets on a straight section between bending magnets. In conventional vibrating-wire alignment techniques, wire sag, which causes alignment errors, is determined from the theoretical catenary curve. By contrast, in the present study, we have measured the sag profiles of various wires in the longitudinal direction to micrometer-order accuracy. We concluded that we can reduce deviations of the actual wire sag from the theoretical curve by choosing a suitable wire. By setting up a test bench of a vibrating-wire alignment system for a series of multipole magnet on a straight section, we have achieved the total error of the magnetic-center measurements of micrometer-order in the standard deviation. Moreover, two systematic error factors, the drift of the magnetic centers due to thermal deformations of the magnets after they are excited and the change in the magnetic centers due to reassembly of the magnets after installing the vacuum chamber, are included in practical magnet alignments. We have experimentally investigated these error factors using the test bench.

Overhead Transmission Line Sag Estimation Using a Simple Optomechanical System with Chirped Fiber Bragg Gratings. Part 1: Preliminary Measurements.

A method of measuring the power line wire sag using optical sensors that are insensitive to high electromagnetic fields was proposed. The advantage of this technique is that it is a non-invasive measurement of power line wire elongation using a unique optomechanical system. The proposed method replaces the sag of the power line wire with an extension of the control sample and then an expansion of the attached chirped fiber Bragg grating. This paper presents the results of the first measurements made on real aluminum-conducting steel-reinforced wire, frequently used for power line construction. It has been shown that the proper selection of the CFBG (chirped fiber Bragg grating) transducer and the appropriate choice of optical parameters of such a sensor will allow for high sensitivity of the line wire elongation and sag while reducing the sensitivity to the temperature. It has been shown that with a simple optomechanical system, a non-invasive measurement of the power line wire sag that is insensitive to temperature changes and the influence of high electromagnetic fields can be achieved.

Calculation of magnetic field intensity under power line with taking into account conductor sag

The paper presents a calculation method of the magnetic field under an overhead power line taking into account conductor sag, which is described by the catenary curve. The calculations take into account the variability of the charge distribution along the conductor and wire sag for the eclectic field, while the calculation of intensity of the magnetic field take into account the impact of induced currents in the wires of lightning. The simulation results were compared with results measurements.

A theoretical study to improve wire sag of ultra-long wire bond loops for 3D/MCM packaging

An innovative theoretical model by altering cross section of gold wire is proposed to reinforce the wire sag stiffness of a wire bond that suffered low yield for the applications of 3-dimensional and multi-chip module (MCM) packaging. The flexural rigidity of a wire bond is found to be a function of the material properties in the moment of inertia of a bond wire. Suffice to say, if the moment of inertia of the bond wire can be raised, the associated sag deflection will be diminished. By manipulating the moment of inertia of the bond wire, the sag deflection of the wire bond can be regulated appropriately to avoid wire sag and even the wire sweep enigma. The ellipse-like cross section of a wire bond is applied as a numerical example to improve the wire sweep stiffness or wire sag stiffness in this study. The results show the sag deflection of a wire bond can be reduced significantly if the ellipse-like cross section is oriented in the preferred direction of flexural rigidity of a wire bond. Furthermore, a systematic study of matching design is performed to control wire sag and wire sweep for the wire bonding applications of overhang cross-stacked and step-stacked packaging. It shows that to use a single diameter of bonding wire in these complicate bonding environments of overhang stacked configurations is a favored possibility. The advantages shown from the theoretical study need to be implemented in further work in a production environment on current wire bonding equipment.

Effects of Stacked Layers and Stacked Configurations on Wire Sweep and Wire Sag of Advanced Overhang/Pyramid Stacked Packages

Overhang and/or pyramid stacked packages are the trend in the semiconductor industry. As the stacked layers increase drastically, the wire sweep and wire sag problems become more and more serious. Based on some types of frequently used stacked configurations, their corresponding wire sweep and wire sag stiffness and deflections are investigated for extra-high stacked layers. Two typical profiles of Q_loop and S_loop wire bonds are included in this study. However, wire sweep and wire sag have to be considered in two different design aspects. For wire sweep, we have the conclusion that the maximum wire sweep deflections always occur near the central segment of a wire bond. As for the wire sag, the maximum wire sag may take place in the center region of the straight portion of a wire bond. The result shows that the deflections of wire sag can be reduced significantly by simply shifting the position of the kink or bend created within a wire bond. Finally, we have concluded that a stacked configuration with smallest bond span may be the preferred selection for the concerns of wire sweep and wire sag issues.

Effect of Minute Bends and/or Kinks of Wire Bond Profile on Sag Deflection for 3-D and Multichip Module Semiconductor Packaging

Wire sag and wire sweep developed during encapsulation process are counted for the lower yield rate of chip packaging in semiconductor industry. For conventional packaging, only one single layer of wire bond was constructed along the perimeter of chip system. The issue of wire sag is not a concern until 3-D and multi-chip modules packaging prevails due to the desperate demands of smaller and faster advanced microelectronics devices. Very few researches have been documented on this subject of sag deflection. An empirical equation based upon major profile parameters of a wire bond has been developed by author to predict sag deflection of ellipse shape wire bond. However, the effect of minute bends and/or kinks of wire bond profile on sag deflection has not been included. In this paper, we investigate three frequently used wire bond loops, ${Q}$ loop, ${S}$ loop, and ${M}$ (modified) loop, to look into these minor characteristics of wire bond profile as compared to bond span and bond height. Based on current results, we find that these minute features may dominate the response of sag deflection of a wire bond.

INFLUENCE OF ENVIRONMENTAL CONDITIONS ON EMF LEVELS IN A SPAN OF OVERHEAD TRANSMISSION LINES

The paper is devoted to the investigation of electromagnetic field distribution in the vicinity of overhead transmission lines under different environmental conditions, taking into account the wire sag curve in a span. A wire state equation is utilized, which allows one to calculate stresses in the wire and sags based on the known stresses and temperatures in the initial state. The results of the electric and magnetic field distribution on sample 330 kV and 110 kV transmission lines are presented. We show that the highest electromagnetic field levels are associated with the most severe environmental conditions, resulting in the highest sag.

Development of an Ultralong Ultralow n-Loop for Wire Bonding

In this paper, we describe an innovative method to form an ultralong ultralow loop for wire bonding. A resister was used to form kinks and simplify the capillary trace, which yielded a loop-like “n”-shape with two kinks immediately above the first and second bonds that can support the entire long-span loop. A 3-D finite element model was developed to simulate the n-loop formation, and the loop profiles of an n-loop, M-loop, and standard loop were compared. In this paper, we show that this novel n-loop can almost halve the looping time compared to that for the M-loop; and the n-loop can avoid wire sag for a 5000- $\mu $ m-long span. Furthermore, the loop height and wire verticality near the second bond can be modified by regulating the horizontal and vertical positions of the resister.

Analysis and experimental concepts of the vibrating wire alignment technique

The vibrating wire alignment technique is a method which, by measuring the spatial distribution of a magnetic field, can achieve very high alignment accuracy. The vibrating wire alignment technique can be applied to fiducializing magnets and the alignment of accelerator straight section components, and it is a necessary supplement to conventional alignment methods. This article gives a systematic summary of the vibrating wire alignment technique, including vibrating wire model analysis, system frequency calculation, wire sag calculation, and the relation between wire amplitude and magnetic induction intensity. On the basis of this analysis, this article outlines two existing alignment methods, one based on magnetic field measurement and the other on amplitude and phase measurements. Finally, some basic experimental issues are discussed.

Aluminum-Clad Invar Super Heat-Resistant Aluminium Alloy Stranded Wire Sag Calculation

Comparison with conventional ACSR aluminum clad ultra-resistant aluminum alloy invar wire with low sag, load flow characteristics, linear expansion coefficient of the wire there is migration point, the migration point temperature coefficient of linear expansion around the wire is different, therefore can not be directly calculated using the equation of state migration point directly after the aluminum clad super-resistant aluminum alloy invar wire sag. This combined with engineering examples, the wire sag derived formulas, combined with the current reality of the design units, presents a practical algorithm for reference.

Empirical Equation of Wire Sag Model for Semiconductor Packaging With Numerical and Experimental Verification

For the semiconductor packaging industry, the issue of wire sag has not been touched upon because only one single layer of wire bond is constructed along the perimeter of the chip system. Over-sag deflections may not cause any problems. However, driven by the demands for smaller and faster advanced microelectronic devices, modern 3-D and multichip modules have become the solution of choice in delivering higher integration and more multifunctional products to meet consumer needs. For 3-D and multichip packaging, excessive wire sag can lead to wires touching against the lower layer, causing a short-circuit and failure of chip functionality. Therefore, gaining knowledge of wire bond sag theory becomes extremely important for advanced packaging. We propose an empirical model to predict the sag stiffness of a wire bond. The sag stiffness of a wire bond is defined to represent its resistance to the sag drag force occurring during the encapsulation process by the molding flow. A higher sag stiffness of a wire bond gives the premise of less sag deflection, thereby avoiding short-circuiting and/or double wire crosstalk due to the closeness of the top-layer to the bottom-layer wire bonds. The theory of sag regarding semiconductor wire bonding has not been documented, to our knowledge, in the literature. Therefore, to deal with this issue, this paper will primarily focus on the theoretical and numerical analysis of sag deflection of a wire bond. A set of sag experiments is conducted to verify the validity of the sag model hypothesis outlined in the earlier paper. Subsequently, an empirical sag model could be put forward to predict the sag stiffness of a wire bond if the corresponding bond spans, bond heights, and material properties are known. The engineered design of a wire bond can be improved through the use of this sag equation. By making use of the proposed sag model, one can attain not only a first-order estimation of the sag deflection but also omit the tedious procedures of numerical analysis.