Insulated Copper Wire Research Articles

Numerical Analysis of Flow Field in Generator End‐Winding Region

Cooling in an end‐winding region of a high‐powered, large‐sized generator still remains a challenge today because of a number of factors: a larger number of parts/components with irregular geometries, complexity in cooling flow paths, flow splitting and mixing, and interactions between rotor‐induced rotating flows and nonrotating flows from stationary sections. One of the key challenges is to model cooling flows passing through armature bars, which are made up of bundles of strands of insulated copper wires and are bent oppositely to cross each other. This work succeeded in modeling a complex generator end‐winding region with great efforts to simplify the model by treating the armature bar region as a porous medium. The flow and pressure fields at the end‐winding region were investigated numerically using an axial symmetric computational fluid dynamics (CFD) model. Based on the analysis, the cooling flow rate at each flow branch (rotor‐stator gap, rotor subslot, outside space block, and small ventilation holes to the heat exchanger) was determined, and the high‐pressure gradient zones were identified. The CFD results have been successfully used to optimize the flow path configuration for improving the generator operation performance, and the control of the cooling flow, as well as minimizing windage losses and flow‐introduced noises.

Improved superfusion technique for rapid cooling or heating of cultured cells under patch-clamp conditions

We have developed an improved technique for fast cooling and heating of solutions superfusing isolated cells under patch-clamp or calcium imaging conditions. The system meets the requirements for studying temperature dependency of all kinds of ion channels, in particular temperature-gated ion channels. It allows the application of temperature changes within a range of 5–60 °C at maximum rates of −40 °C/s to 60 °C/s. Barrels filled with different solutions are connected to a manifold consisting of seven silica capillaries (320 μm inner diameter, i.d.). A common outlet consists of a glass capillary through which the solutions are applied onto the cell surface. The upper part of this capillary is embedded in a temperature exchanger driven by a miniature Peltier device which preconditions the temperature of the passing solution. The lower part of the capillary carries an insulated copper wire, densely coiled over a length of 7 mm, and connected to a dc current source for resistive heating. The Peltier device and the heating element are electrically connected to the headstage probe which is fixed on to a micromanipulator for positioning of the manifold. The temperature of the flowing solution is measured by a miniature thermocouple inserted into the common outlet capillary near to its orifice which is placed at a distance of less than 100 μm from the surface of the examined cell. The temperature is either manually controlled by voltage commands or adjusted via the digital-to-analog converter of a conventional data acquisition interface. Examples are given of using the device in patch-clamp studies on heterologously expressed TRPV1, TRPM8, and on cultured rat sensory neurons.

Indirect Measurement of AC Current Distributions in a Bi-2223 Solenoidal Coil by a Pickup Coil Method

In order to investigate AC current distributions in high Tc superconducting (HTS) coils, we have developed a measurement method to evaluate the current distributions in a HTS solenoidal coil. In this method, the current distributions are indirectly found from the results of the field distributions measured by pickup coils located around the sample coil surface. To confirm the accuracy and sensitivity of this method, current distributions in a test coil made of insulated copper wires are measured. Numerical and measured field distributions are compared, and it is found that our method is accurate enough to measure the current distributions for the HTS coils. Using this method, we measured the current distributions in a Bi-2223 solenoidal coil at room temperature and 77 K. The comparison between the experimental and numerical results shows that the current distributions in the HTS coil are not uniform. On the basis of the obtained results, the characteristics of the AC current distributions in the HTS coils are discussed.

The Early History of Insulated Copper Wire

In the early 1800s galvanometers could be constructed with the fine gauges of silk-covered copper or silver wires produced for decorative purposes, but when Faraday was making his classic electrical experiments in 1831 he needed a sturdier gauge of copper wire. Bare copper wire was available in many diameters for mechanical applications, but coils for electromagnetic investigations had to be insulated with string and calico. It was soon realized that the cotton-covered springy iron wire then used to hold out the brims of ladies' bonnets showed how copper wire might be similarly wrapped to provide a flexible insulation. The simple manual machines used by the bonnet-wire makers were readily adapted and improved, and a six-head version was built by William Henley. This craftsman's vision of the growing importance of insulated copper wire was abundantly justified, and he built up a large—but poorly organised—empire in the wire and cable trade. Henley's original multiple-head wrapping machine has been located in the Science Museum, London, and the associated silk-covered copper wire subjected to physical, chemical, and electrical testing. For comparison, the electrical conductivity of the ‘mechanical grade’ copper wire used by Faraday has also been determined.

Endovenous Radiofrequency Ablation using Stent-type Electrode for Varicose Veins: an Experimental Study in Goats

Purpose: The purpose of this study was to investigate the feasibility and the optimal conditions of radiofrequency (RF) ablation by using the stent-type electrode upon the saphenous vein of goats for the endovenous treatment of varicose veins. Materials and Methods: A self-expandable nitinol stent electrode (6 mm diameter, 2 cm length, cell size; 1.32 mm) was designed to expose the distal 1cm segment to allow for contact with the venous wall. The proximal part of the electrode was connected to the RF generator by insulated copper wires located within the stent electode introducer. Initially, to optimize the power setting, ablation of 6 saphenous veins in 3 goats was performed with power settings of 10, 20 and 30 W. Pull back rate of the electrode was 2 and 4 cm/min for each power level, respectively. The goats were sacrificed 4-6 weeks later and histologic examinations of the saphenous veins were done. For the second part of the experiment, RF ablation of 4 saphenous veins from 2 goats was done by applying the optimal power, based upon the first examination; these procedure was performed with variable pull back rates. Again, the goats were sacrificed 1-6 weeks later and histologic examinations were done. Results: Endovenous ablation of the goat saphenous veins at 20 W caused complete obliteration without complication. There was incomplete occlusion at 10 W, and there were vessel perforation, extravasation, and adjacent tissue injury at 30 W. In second part of the study, the complete circumferential obliteration of the vein was demonstrated at a pull back rate of 1 cm/min and 3 cm/min with the power of 20 W. Conclusion: The stent-type electrode may be useful in endovenous RF ablation for treatment of varicose veins. For stents with a diameter of 6 mm, the optional combination of 20 W of power with a pull back rate of 1-3 cm/min produced the most favorable results. Further study and clinical nvestigations are warranted.

Measurement of AC current distributions in HTS tapes exposed to an external AC magnetic field by a compensated pickup coil array

A new system was developed for measuring AC current distributions in high T/sub c/ superconducting tapes under an external AC magnetic field. In our measurement the current distributions are indirectly found from the results of the self-field distributions measured by an array of pickup coils located around the tape. For improved measurement accuracy under the external magnetic field, a compensation coil was used to cancel the component of the external magnetic field from the signal of pickup coil. In order to confirm the validity of this system, measurement of current distributions in a test conductor composed of insulated copper wires was carried out under an external AC magnetic field. Using this system, we measured the current distributions in multifilamentary Ag alloy sheathed Bi-2223 tape as a function of the angle of the external AC magnetic field at 77 K. Further, we investigated the characteristics of the current distributions for the case of a simultaneous application of AC transport current and transverse AC magnetic field. On the basis of the obtained results the practicality of our measurement system is discussed.

Ultrasonic power measurements in the milliwatt region by the radiation force float method

The radiation force float technique is extended in the present investigation, for the determination of the total radiated low ultrasonic power in the milliwatt region. It is elucidated, experimentally, using floats having a conical reflecting target comprising of new material (teflon insulated copper wire) stems with smaller diameters (0.55 and 1 mm). The sensitivity is improved with these two stems and the ultrasonic power levels are measured in the range from 1.4 to 140 mW and 4.6 to 460 mW respectively and the results are reproducible within ±5%. Limitations of float technique and factors influencing the uncertainties involved for the high quality ultrasonic power measurements are discussed. The proposed method is simple, versatile and inexpensive and can be used as an interim standard.

Indirect measurement of current distributions in Bi-2223/Ag tapes by pickup coil method

We develop a quantitative measurement method to evaluate current distributions in high T/sub c/ superconducting tapes. In our measurement the current distributions are indirectly found from the results of the self-field distributions measured by a group of coils, which is composed of nine small pickup coils, located around the tape. It is confirmed that the accuracy and the sensitivity of this measurement method, using a group of pickup coils, are good enough to measure the current distributions for the high T/sub c/ superconducting tapes by adopting it to a dummy conductor composed of insulated copper wires. Using this method, we have measured the current distributions in multifilamentary Ag-sheathed Bi-2223 tape at 77 K. Measured and numerical self-field distributions are compared. The comparison between the experimental and numerical results shows that the current distribution in the tape is not uniform and that distribution changes as the amplitude of the transport current increases. In addition, no frequency dependence of the current distributions is observed. Further, we investigate the influence of the external magnetic field on the current distributions. On the basis of the obtained results the characteristics of the current distributions in the high T/sub c/ superconducting tape are discussed.

絶縁被覆銅線を用いた高密度多層配線板における信号伝搬遅延時間の高精度制御設計技術

We have developed a new technique of adjusting propagation delay time of Multi-Wire Boards (MWBs) . MWBs use polyimide insulated copper wires for signal connection. The wires will intersect each other. Therefore, in high-density wiring, improper variation in the delay time will be caused by intersections of wires, adjacent through holes, folded wires, and via holes in the middle of wiring. A new estimation method was proposed and the influence of these factors on the variation of the delay time was investigated. It was found that about 73% of the variation is caused by the intersection of wires. With this new technique, it is possible, after finishing the routing design, to control the length of the wiring, and adjust the propagation delay time so that it is equal to that calculated by a newly developed software. We confirmed that the variation time of the boards designed in this way decreases to one-third or less of that of the conventional MWBs.

Current distributions at steady-state of superconducting cable conductors for AC use

In order to obtain information towards achieving uniformity of current distribution in superconducting cable conductors for AC use, the authors have developed a compact measuring system that enables them to quantitatively evaluate the current distribution. In this system, current distribution is found from the observed results of the self-field measured by a group of coils, each of which is composed of six small pick-up coils, located around the sample conductor. It is confirmed that the accuracy and the sensitivity of this system are good enough to measure the current distributions for the superconducting cable conductors for AC use by adopting it to a dummy conductor composed of insulated copper wires. Using this system, they experimentally investigated how the localized transport current, in the steady-not quenched state, is made uniform in the superconducting cable conductor composed of strands without insulation for AC use. By this experiment, they observed how the localized current transfers among the noninsulated strands. At the same time, the frequency dependence of the change of the current distribution can also be observed as well. These measured results are discussed using approximate analysis relating to the inter-strand coupling effect.

Ｓｎめっき端子を利用した被覆銅線の抵抗加熱接合

A new brazing method was developed and investigated in order to improve the bonding strength of insulated copper wires using fusion technology. The process was composed of fusing and press-soldering, which was a direct joining of copper terminal and insulated copper wire. Insulated copper wires wrapped with a tin plated copper terminal were heated simultaneously by resistance heating to be bonded. The tin plating layer was used for press-soldering.The room temperature tensile strength increased with resistance heating current until above 3.0 kA and the fracture in base metal occurred in the copper wires, for bonding above a current of 4.2 kA. In the elevated temperature tensile testings, rupture in base metal were observed at 150°C and 250°C. The results showed excellent thermal resistance of the joints.

Measuring the speed of digital signals (speed of light)

An odd number of digital not-gates connected in a closed loop circuit will produce a relatively stable free running oscillator. The frequency of oscillation is determined by the number and type of not-gates, the circuit supply voltage, and the total length of connection wire used between the not-gates. Measuring the frequency for various lengths of connection wire enables the speed of the digital signals in the wire to be calculated. The method is sensitive enough to reveal that signals traveling in 22 gauge insulated copper wire propagate about 5% slower than those in 22 gauge bare copper wire. The speed in insulated wire is (2.87±0.03)×108 m/s and the speed in bare wire is (3.03±0.02)×108 m/s. This experiment has been found to be a very popular undergraduate laboratory due to its low cost, straightforward theory, and relatively high (∼1%) precision. The absence of a light source eliminates complicated optics and impresses students with the fact that visible light is not the only thing that travels with the speed of light!

絶縁被覆付銅コイル継手の耐久性評価

A new brazing method was investigated in order to improve the strength of insulated copper wires jointed by fusion technology. This process of the brazing method is composed of fusing and brazing for joining brass terminal and insulated copper wire.Shear tests of the joint were carried out at room temperature after each test, namely, 2000h exposure at 150°C or 250°C, 1000 thermal cycle test between -55°C and +150°C, and salt spray test at 35°C for 2000h.After durability test, We observed the joint interface and find Cu, Ag, P and a little Zn. In these tests, the fracture are observed at the base metal without damage at joint region.Moreover, the strength of the joint between a wire without insulating coat and a brass terminal was also evaluated, and equivalent strength is obtained as that given in case of the wire with insulating coat.

NMR imaging of 15N at natural abundance

*‘N observation at natural abundance (0.37% of total nitrogen) has become conventional in NMR spectroscopic studies on liquids since the first report in 197 1 ( 1) . This technique has also been useful for solving problems in solids (2). Experiments involving enriched material have proved to be important in labeling studies in chemical applications (3)) in determination of protein structure (4)) and in improving the understanding of plant metabolism (5,6). In the case of plants, crude spatial selection has previously been achieved by physical sectioning of plants which had been fed with “N-labeled nutrients ( 5 ) . No 15N NMR images from samples at either natural abundance or enriched concentration have previously been reported, and only one 14N image (of liquid nitrogen) had been published ( 7) until recently (8). Given the ubiquity of nitrogen in metabolic processes and the interest in the processes of nitrogen fixation and nitrogen turnover in the environment, it seemed sensible to tackle the particular problems associated with ‘*N NMR imaging. These, as in 15N NMR spectroscopic studies, arise from the low isotopic abundance and the low magnetogyric ratio, which give the 15N isotope a receptivity of only 3.85 X 10e6 compared to ‘H. An additional drawback is the long relaxation times frequently encountered ( 9). This renders accumulation difficult but does at least ensure that “N lines are normally narrow. A faster accumulation rate may, however, become beneficial if relaxation times are shortened by the use of paramagnetic reagents or if steady-state techniques are employed. The maximum concentration of 15N spins at natural abundance occurs in liquid nitrogen, for which the molarity of i5N nuclei is 0.2 1 M. Additionally, low temperature (77 K) gives a favorable Boltzmann gain relative to 298 K of about 4 as well as reduced thermal noise to give an overall gain of approximately 7.5. The signal-to-noise ratio was measured to be approximately 10: 1 following a single 90” pulse and the linewidth was less than 70 Hz. The relaxation times are presumably shortened by contamination with oxygen, the amount of which varies from sample to sample. The sample was contained in a two-section, unsilvered Dewar and was bubbling while under investigation so that the signal-to-noise ratio was reduced by removal of magnetized material from the active volume of the RF coil. The upper section functioned as a reservoir and was 8 cm high (od, 6.5 cm) and ended in a finger (id, 1.7 cm and height, 7.5 cm) which was inserted into a lo-turn surface coil (id, 3.0 cm) made of 0.8 mm insulated copper wire. There was sufficient volume of liquid nitrogen in the reservoir to keep the finger full for 3 1 hours.

絶縁被覆付銅コイルの金属接合技術

A new barzing method was investigated in order to increase the strength of fusing joints of insulated copper wires. This process is a combination of fusing and brazing of brass terminal and insulated conner wires.The filler metal, the brass terminal and the wires were heated simultaneously by resistance heating, and they were bonded. The joint which was brazed at about 700°C using BCuP-5 (Cu-15%Ag-5%P) filler metal gave the best result. That joint fractured at the insulated copper wire (base metal) in tensile testing.A joint layer which consisted of mainly Cu, Ag, P and a little carbide was formed at the joint interface.

An Enclosure for Protecting Small Mammal Traps from Disturbance

An Enclosure for Protecting Small Mammal Traps from Disturbance

Experimental Study of a Practical AIRGAP Winding Stator Arrangement for Large Turbine Generators

Experimental studies of 2 kA water cooled armature bars composed of fine multi-transposed insulated copper wires and of a special airgap winding stator arrangement in a 4MVA 3 phase generator are carried out. Four different kinds of bar configuration are examined and data fundamental to practical generator applications is obtained. An advanced armature winding configuration, which is called a Skew Winding, and a special winding support system are investigated in the 4MVA generator, and the possibility of practical applications is demonstrated experimentally.

Displacement transducer using impedance variations due to core torsion

The wide obtainable range of mechanical compliance encourages the application of helical magnetostrictive springs in force and pressure transducers as well as for direct displacement sensing. In the usual mode of operation, an alternating current is conducted through the magnetostrictive wire, and an output signal (related to the axial compression or extension of the spring via torsional stress anisotropy) is obtained from as insulated copper wire solenoid wound on the helical spring wire. Sensing the strain by the variation in impedance of this solenoidal winding provides an alternative mode of operation that allows a substantial decrease in the excitation current; an attractive prospect for applications concerned with intrinsic safety and energy usage. Suitable spring materials are found among the Ni-Fe Permalloys. Impedance is found to decrease monotonically with torsional strain (displacement). Variations of more than 2 to 1 are found to be markedly insensitive to excitation current and frequency over several orders of magnitude. This mode of operation is easily implemented with simple electronic multivibrator or other oscillator circuits, physically small enough to be incorporated within the case of practical transducers.

An Electrically Heated Buried Gathering System Transports High-Pour-Point Crude Oil

This paper describes two electrical heating systems that are being used successfully on buried flowlines transporting crude oil with 70 to 90 degrees F pour points. The electrical systems, insulation, and protective outer jackets are discussed. Installation and operating costs and problems also are presented. Introduction The Dickinson Heath Sand Unit (DHSU) is located about 1 mile north and 1 mile west of Dickinson, N.D. (Fig. 1). This unit has 37 producing wells, one water well, and 14 injection wells located in 26 sections, The wells are completed in the Heath sand at 7,900 to 8,100 ft and produce 33 to 35 degrees API crude oil with pour points produce 33 to 35 degrees API crude oil with pour points of 70 to 90 degrees F. A waterflood began in Dec. 1973. Production has not peaked. The unit produced 4,409 BOPD and 4,600 peaked. The unit produced 4,409 BOPD and 4,600 BWPD with water injection rates of 9,800 B/D during June 1977. Before unitization, each well had its own tank battery. The heater treaters were located about 120 to 200 ft from the wellhead. Even with these short flowlines, pressures of more than 2,000 psi sometimes were needed to displace the congealed crude oil. After the waterflood began, a water gathering system was necessary. Because this system would cost %1,300,000, a total produced-fluids gathering system with one central battery was economically attractive. Therefore, many methods of transporting the high-pour-point crude oil were investigated and evaluated. However, most methods were either too expensive or the flowlines would be plugged after a long shutdown. The only way to remove the congealed oil would be to install pump-out risers about every 200 to 500 ft and displace the oil with hot water under high pressure. Two methods for electrically heat-tracing insulated lines were found that appeared feasible for the gathering system. These were the Skin Effect Current Tracing (SECT) and the Thermon systems. It was decided to test these systems on four lines in 1974. The SECT System Principle Principle The SECT heating element used in our system is a 1/2-in. Schedule 40, black iron pipe that is welded to the carrier pipe. The welds are spaced evenly the entire length of the pipe. The welds are spaced evenly the entire length of the carrier pipe with 2-in. passes separated by 2-in. open spaces. The welding attaches the heating element (or "heat tube") to the pipe and provides a heat path to the pipe. A single, insulated copper wire passes through the pipe. A single, insulated copper wire passes through the center of the heat tube and is connected to the heat tube at the far end (Fig. 2). Alternating electric current flows through the wire and the heat tube and creates heat by the resistive loss of the well known I2R principle (Joule's law). The magnetic fluxes surrounding the current in both the tube wall and the wire concentrate in the inner wall of the heat tube because of the high magnetic permeability of mild steel. The interaction of these two fluxes creates the "skin effect" that causes the current in the heat-tube wall to concentrate near the inner surface (0.005 in.) and be essentially nonexistent at the outer surface. JPT P. 890

Laser spot welding and real-time evaluation

The high-repetition-rate pulsed-YAG-laser welding of insulated copper wires to terminal posts and their real-time evaluation with stress-wave emission (SWE) are discussed. It is shown that to minimize damage to the wire from the incident radiation a shoulder terminal, wherein the shoulder covers the wire, is desirable. The experimental and the analytical results show that for the geometry a terminal made out of higher melting-point material than copper is desirable. SWE techniques have been used to predict the quality of a laser weld in real time. An experimental criterion has been established for such a prediction. This criterion has been verified by resistance measurement, visual observation, and, to a limited extent, mechanical-pull testing. It is shown that an almost linear relation exists between the threshold crossings of an SWE signal and the quality of the weld.