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This paper presents a method of monitoring the stress level of a company's employees, pupils or students who are working on their computer. The functioning of sweat glands in certain areas of the body, such as palms, arms and soles, is activated by psychological stimuli, independent of external temperature or physical effort, a phenomenon that translates to the skin level by altering the electrical...
Thermal greases allow a low stress bond at low bond line thicknesses (BLT) at medium thermal conductivities and simple application, all of which make it an alternative to solders, thermal adhesives or pads. It is widely used in power and microprocessor applications, most of which involve large areas to be used for heat transfer. However, for years thermal overload failure of power modules and chips...
Nanocomposite material for power cable insulation has been under extensive research for quite a long time. Advanced organic and inorganic nano filler of metals and non metals with conductive, semi-conductive and insulating inheritance were wide options. The authors prepared and investigated nanocomposite samples made with low density polyethylene as base resin with several nanofillers including nanofiller...
The article substantiates the use of the resistance-acoustic method in problems of non-destructive testing of mechanical stresses or defects in structures of metals and alloys in natural and technical systems. The possibilities of the use of the proposed method for the potential monitored facilities were analyzed, to which the strict requirements for operational security are imposed (bearing reinforced...
Insulating oils have been used as dielectric materials in transformers, and also in capacitors and cables. The main advantages of insulating oils are low cost and their superior insulating properties. However, once oils leaks from the equipment, it adversely affects the environment. Therefore, we focused on ultra-pure water (UPW) as one of environmental friendly liquid insulating materials. In this...
A finite element model which contains one sixth of the IGBT module based on a real test chip of IGBT module is established to investigate the temperature and stress distribution of different shape bonding wire. The finite element (FE) analysis which coupled electro-thermal and thermal-mechanical are conducted using commercial software ABAQUS. The thermal performance and stress distribution of IGBT...
Rapid economic developments have forced power networks and pipeline networks to share the same pathway. Induced voltages and currents appear on pipelines running parallel with high voltage transmission line when the transmission line is hit by lightning strike. In this study, a simulation had been carried out to determine the first lightning stroke effect on an underground pipeline coating stress...
In this study, we synthesized a self-healing electrically conductive gel based on Agar/hydrophobically associated polyacrylamide (HPAAm) by a restraint-assisted method. Recently, self-healing conductive materials based on such gels have been widely researched. However, as gels are generally weak, the gel-based materials are also often low in strength. Therefore, in this study, we applied the restraint...
Voltage source, pulse width modulated (PWM) drive system finds many industrial applications such as pumps, fans, compressors and other equipment, with the benefit of both productivity improvement and greater energy efficiency. However, medium and high voltage PWM motors suffer from premature insulation ageing. Several types of ageing processes in medium and high-voltage stator windings has been identified...
The decentralized generation of electrical power continues to rise which means that also the transport of electrical power over larger distances is gaining more and more importance. High voltage direct current (HVDC) transmission provides an efficient means to transmit large amounts of electrical power over long distances.
We have developed a new method “direct current integrated charge (DCIC) method” for evaluating a deterioration of insulating materials in power equipments. The three important dielectric parameters, that is, conductivity, relative permittivity, and accumulated charge amounts are evaluated simultaneously by a relatively simple treatment of the method. Since the total amount of charges is found as an...
This paper reports an amorphous CoTix alloy as a single-layer liner/barrier material for intermediate interconnects in place of bilayer Ta/TaN materials. The CoTix layer was found to enhance adhesion of Cu/SiO2. The CoTix layer stayed amorphous after annealing at 400°C, and started to crystallize at 500°C. Capacitance-voltage measurement of the samples showed no interdiffusion of Cu ions into SiO2...
In this paper the boundary value problem for the thermal conductivity of an isotropic piecewise homogeneous plate with a through foreign inclusions, heated heat flow, focused on one of its boundary surfaces is considered. Thermal conductivity of the entire system as a whole is described by means of asymmetric single function. The result is a heat equation with discontinuous and singular coefficients...
This paper deals with the thermal, electrical and combined thermo-electrical ageing of some XLPE and EPR flat samples. The samples were aged for different ageing times and electric fields. Before and after ageing, the electrical properties (e.g. electrical conductivity and permittivity) were measured. The physical modifications of the specimens were analyzed, also. Combined stresses (electrical and...
This paper proposes an optimal defect shape to increase the sensitivity of a MEMS cantilever based piezo resistive sensor. This work describes the sensitivity improvement using Stress concentration region (SCR) introduced in the cantilever beam. The SCR improves the surface stress on the cantilever beam and enhances the sensitivity of the sensor. A particular defect (sigma star) is introduced which...
By using the Finite Element Method (FEM), calculation techniques of electric field distribution for AC, DC voltages and DC polarity reversal conditions were developed in oil-pressboard (PB) composite insulation systems. By using PB layered models under HVDC conditions, it was recognized, the electric field distributions were remarkably controlled by PB arrangement in oil. In particular, it was clarified...
Carbon-based semi-conductive materials (corona armor tape or CAT), and SiC-based nonlinear grading materials have been used widely to reduce the electric field in the region where the stator bar exits from the slot in form-wound rotating machines. Recent studies show that electric field and local heating in the end-turn stress grading system become severe under PWM waveforms and high frequency repetitive...
The presence of defects for instance, the conductive particles (contaminants) in the insulating material of high voltage cables (HV) constitutes a major concern for the cables manufacturers and electrical power utilities. Their existence, in the insulation can cause partial discharges in service leading to an accelerated aging of the cable and therefore its failure. In this work, a two dimensional...
In this contribution, influence of dry bands on electric field distribution on a polymeric insulating surface has been carried out using Finite Element Method. Formation of dry bands on insulating surfaces result in electric field enhancement leading to surface discharges, dry-band arcing etc. which in turn affects the long term performance of the insulators. Hence, in the present work, a polymeric...
Shape Memory Alloy actuators are microactuators that are known for their high actuation-force and -strain. Limiting the application of Shape Memory Alloy actuators is the lack of suitable control algorithms that can deal with the highly non-linear dynamics of the actuator. The latter suffers from hysteresis and is characterized by the changing crystallographic structure of Shape Memory Alloy. In this...
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