Developing glass composition for glass coated In and Sn cast microwires

The paper presents the results of research and development of glasses for insulation of cast microwires of the PbO - SiO2 - Na2O - InO2 - SnO2 system. The optimal composition has been determined, which makes it possible to establish a stable process of casting microwires from indium and tin with a length of more than 1000 meters. It is shown that from such microwires it is possible that small base fusible fuses with a high melting current density could be manufactured.

Influence Estimation of the On-Load Tap-Changing Transformeron the Currents in Schemes of Ice Melting on Overhead Transmission Lines

The influence of regulated under load transformer's (on-load tap-changing transformer) ratio and imped-ance on the short circuits’ currents and currents in the schemes of ice melting with AC and DC current is ana-lyzed. Accounting for changes in the transformer ratio is not difficult as it is provided in the technical data for all branches (tap positions). The transformer resistances used in the calculations, which are reduced to the un-regulated side of the transformer, are proportional to the short-circuit (SC) voltages. SC voltages are known, according to GOST, only for three tap positions - main (middle) and two extreme (top and bottom) positions, and for other tap positions are determined approximately according to different methods. It is shown on the typical example, that the error of the melting current calculation is significantly less than the error of the ap-proximated transformer's resistance calculation by the method of linear interpolation of resistances, the error of which for different types of on-load tap-changing transformers does not exceed 3 %.

Thermodynamic model of critical ice-melting current on iced transmission lines

The thermal de-icing by Joule effect is a mostly valid way to prevent transmission-lines from the severe ice storm. A model was put forward to simulate the critical ice-melting current on iced conductor. Based on this model, the value of critical ice-melting current was calculated with various parameters, some of which were ignored in the earlier literatures, such as ice-layer heat conductivity, wind attack angle, and icing section shape. The results of the experiment and simulation show that the critical ice-melting current increase with wind speed, wind attack angle, and ice-layer heat conductivity, but decrease rapidly with ambient temperature and liquid water content. Moreover, the maximum difference between the results of simulation and experiment is about 9%, thus this model can be employed to estimate the engineering parameters in practical thermal de-icing projects.

Mathematical Modeling of the Mold Current and Its Influence on Slag and Ingot Behavior during ESR

ElectroSlag Remelting (ESR) is widely used to produce high added value alloys for critical applications (aerospace industry, nuclear plants, etc.). In collaboration with Aubert & Duval, Institut Jean Lamour has been developing for several years a numerical transient model of an ESR heat. In the previous version of the model, the crucible was assumed to be perfectly electrically insulated from the electrode-slag-ingot system. However, this assumption must be challenged: the solidified slag skin at the slag/mold and ingot/mold interfaces may actually allow a fraction of the melting current to reach the crucible. In this paper, an evolution of the model is presented that enabled us to take into account the possibility of mold current. The simulation results were compared with actual experimental data. Sensitivity studies showed the influence of slag properties and operating parameters on the final quality of the ingot. Results highlighted that even a weakly conductive solidified slag skin at the inner surface of the model can be responsible for a non-negligible amount of current circulating between the slag and crucible, which modifies the fluid flow, heat transfer and solidification of both the slag phase and the metallic ingot.

Investigation of Melting Current in Glass Tube Fuses

This paper presents a study of melting current in the commercial glass tube fuses to determine the duration of melt, maximum melting current and maximum power consumption of the fuse in a blowing circuit. A microcontroller is used as a device to measure and collect the values of current, voltage, and power consumption. In the experiments, the glass tube fuses rated of 0.5 A, 1 A, 2 A, 3 A, 5 A, 10 A, 15 A, and 20 A were used. The experimental results show that the melting time were approximately 0.05 s, 0.07 s, 0.11 s, 0.13 s, 0.18 s, 0.20 s, 0.28 s, and 0.40 s; the maximum of melting current were approximately 0.66 A, 1.17 A, 3.81 A, 13.77 A, 20.80 A, 25.05 A, 26.66 A, and 29.96 A; the maximum of blowing voltage were approximately 12.25 V, 12.25 V, 12.30 V, 12.15 V, 12.10 V, 12.29 V, 12.10 V and 12.20 V; and the maximum of blowing power consumption were approximately 7.53 W, 14.22 W, 45.57 W, 158.49 W, 224.38 W, 242.21 W, 230.63 W and 283.68 W respectively.

Macroscale Modeling of Multi-Physics Fields during Vacuum Arc Remelting of Ti-6Al-4V

A 3-D finite element model has been established using ANSYS12.0 software to simulate multi-physical interaction behavior during the Vacuum Arc Remelting (VAR) of 740-mm-diameter ingots of Ti-6Al-4V. The models of temperature field, electromagnetic and flow field were combined by progressive method. The effect of thermal contraction was considered in the simulation of temperature field and electromagnetic by setting a thin layer with different nature parameters at the ingot-crucible interface. The model results demonstrate the distributions of temperature, Lorenz force and flow velocity, and the influence of water cooling conditions, melting current and other process parameters. The molten pool behavior is mostly dominated by buoyancy force under circumstances in this case. The increase of the melting current results in an increase of the pool depth and melting rate, and causes great change of the molten pool profile, while the influence of the water cooling conditions is ignored.

Stress Simulation for DE-GMAW in Bonding Steel with Aluminum

DE-GMAW (Double-Electrode Gas Metal Arc Welding) is a new welding technology. It is possible to change the melting current while the base metal current still be controlled at a desired level because the changed part of the melting current would be bypassed without flowing through the workpiece. So the heat input of base metal can be controlled accurately in DE-GMAW, and this welding method is suitable for dissimilar metal welding which has strict requirements for heat input of base metal, such as joining of steel and aluminum. On the basis of heat source model of DE-GMAW, numerical simulation and analysis on temperature field and residual stress for DE-GMAW in bonding steel and aluminum were done. The results show that residual stress after welding changed sharply from close 0 MPa to about 130 MPa at the interface of aluminum and steel. This value is greater than the binding force of steel, aluminum interface.