Composite Electrical Insulation Research Articles

Modeling of the Transient Electric Field in Multilayer Dielectric Composites Under Impulsive HV Energization

This article presents the theoretical analysis of composite electrical insulation, formed from layered dielectric materials and subjected to impulsive energization. The 1-D planar and cylindrical geometries were considered, consisting of an arbitrary number of layers with arbitrary relative permittivity and electrical conductivity. Analytical solutions have been successfully derived for the time-dependent electric field inside the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${i}$ </tex-math></inline-formula> th layer. To demonstrate the usage of the model under complex multilayer topologies where analytical solutions are nontrivial, the characteristics of a 20-layer-graded composite under microsecond and sub-microsecond impulses were analyzed and validated against a finite-element (FE) solver. Results indicate that the transient electric field response under impulsive energization is strongly dependent on the interplay between the composite relaxation time constants and the characteristic timescales associated with the applied impulse. The model is a further development for the design and coordination of functionally graded materials (FGMs) and composite insulation for high-voltage (HV) system design. This is particularly relevant under fast-rising impulsive conditions as often encountered in many pulsed power applications.

Influence of thermal conducting inclusions on the limiting potential difference of polymer composite electrical insulation

Influence of thermal conducting inclusions on the limiting potential difference of polymer composite electrical insulation

Increasing performance of soft dielectric elastomer artificial muscles via nanomaterial composite electrical insulators

Increasing performance of soft dielectric elastomer artificial muscles via nanomaterial composite electrical insulators

Electrical Insulation Tape Winding and Inspection System

An electrical insulation web winding and optical inspection system has been developed to provide semiautomatic material handling and machine vision inspection of composite electromagnet coil insulation materials. Composite electrical insulation for electromagnet conductor insulation typically comprises a nonconductive woven filler (typically S-Glass), nonconductive film (typically Kapton®), and fixating resin. Prior to the subject system, the stock woven filler and film used to assemble the composite structure were inspected manually for dimensional and foreign matter presence, which did not provide 100% inspection. The subject system features a web handling reel-to-reel transfer mechanism that includes an open-loop web positional alignment device to maintain the web centerline position. A machine vision system is used to optically inspect passing web materials for dimensional defects and foreign materials. This system is capable of inspection of single web woven filler material and/or colaminated woven filler material and nonconductive film. A detected defect automatically terminates web movement, generates an alarm, and records images of the defects on a media storage device. Prototype material inspections performed by the subject machine on approximately 21 567 m (70 759 ft) of material detected 174 pieces of debris.

The Influence of Alloy Elements on the Mechanical Features of Nanostructured Composite Materials with Recovered Silicone Rubber Matrices

The following paper indicates variants of new materials obtained with various organic alloy elements. Our research has used recoverable silicone rubber, obtained from used scrapped silicone rubber, used for the tyre of 24 kV composite electrical insulators as a basic matrix, under the form of silicone powder, liquid silicone rubber to various proportions, along with nanopowders obtained through recycling

Quench-Induced Dynamic Breakdown Characteristics of &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$\hbox{LN}_{2}$&lt;/tex-math&gt;&lt;/inline-formula&gt; and &lt;inline-formula&gt; &lt;tex-math notation="TeX"&gt;$\hbox{LN}_{2}/\hbox{PPLP}$&lt;/tex-math&gt;&lt;/inline-formula&gt; Composite Electrical Insulation System for Superconducting Power Apparatus

In HTS power apparatus, quench due to the fault current generates dynamic electrical/thermal combined stress. This stress may induce the electric breakdown (BD) under the operating voltage. We investigated the quench-induced dynamic BD characteristics of $\hbox{LN}_{2}$ . In addition we investigated the quench-induced dynamic partial discharge characteristics of $\hbox{LN}_{2}$ /polypropylene laminated paper composite electrical insulation system for HTS cables. The criteria of the combined electrical/thermal stress for the dynamic BD were obtained for both test samples, and the reduction rate of the dynamic BD criteria against the static BD criteria without thermal stress was discussed.

REGARDING THE DYNAMIC CHARACTERISTICS OF FIBERGLASS REINFORCED EPOXY RESIN RODS RECOVERED FROM USED COMPOSITE ELECTRICAL INSULATORS

The paper presents a methodology for determining the dynamic characteristics fiberglass reinforced epoxy resin rods recovered from used composite electrical insulators. These are important for studying the dynamic stability and mechanical resistance under the action of external disturbing factors. There is presented the required measuring equipment and the rod mounting system for measurement. Experimental modal analysis (EMA) is used; the modal shapes are geometric representations of the dominant structure movements at proper frequencies. Identifying the proper oscillations is important for the given structure, resonance displacements indicating material wear and fissures in the framework. Research has identified the frequency response functions (FRF) and from their analysis it was determined the resonance frequency based on which can be determined the modal parameters of the analyzed rod. Keywords—composite electrical insulator, epoxy resin rod, modal analysis, proper frequencies, resonance frequency, modal parameters

Stress Analysis and Detection of Composite Electrical Insulators with Embedded Fiber Bragg Grating Sensors

Stress Analysis and Detection of Composite Electrical Insulators with Embedded Fiber Bragg Grating Sensors

Thermal conductivity and Kapitza resistance of cyanate ester epoxy mix and tri-functional epoxy electrical insulations at superfluid helium temperature

In the framework of the European Union FP7 project EuCARD, two composite insulation systems made of cyanate ester epoxy mix and tri-functional epoxy (TGPAP-DETDA) with S-glass fiber have been thermally tested as possible candidates to be the electrical insulation of 13T Nb3Sn high field magnets under development for this program. Since it is expected to be operated in pressurized superfluid helium at 1.9K and 1atm, the thermal conductivity and the Kapitza resistance are the most important input parameters for the thermal design of this type of magnet and have been determined in this study. For determining these thermal properties, three sheets of each material with different thicknesses varying from 245 to 598μm have been tested in steady-state condition in the temperature range of 1.6–2.0K. The thermal conductivity for the tri-functional epoxy (TGPAP-DETDA) epoxy resin insulation is found to be k=[(34.2±5.5)⋅T−(16.4±8.2)]×10−3Wm−1K−1 and for the cyanate ester epoxy k=[(26.8±4.8)⋅T−(9.6±5.2)]×10−3Wm−1K−1. For the Kapitza resistance, Rk, the best curve fitting the experimental data is described by Rk=(3057±593)×10−6⋅T (−1.79±0.34)m2KW−1 for the TGPAP-DETDA insulation and Rk=(4114±971)×10−6⋅T (−1.73±0.41)m2KW−1 for the cyanate ester epoxy insulation. Our results are compared with other epoxy based composite electrical insulation found in the literature.

Measuring the Electric Strength of Board Composite Materials and Insulators

This article contains the results of electric strength measuring of board composite materials and electrical insulators. It describes and briefly specifies the measured materials, i.e., the composites based on Glass, Kevlar and Carbon fiber. The composite electrical insulators are Kartit, Glasstextite and Textite. The measurement description shows the measurement system diagram and parameters of the used testing high-voltage source. The evaluation suggests the possibility of using composite materials as electromobiles' construction components which require specific electrical properties.

Acoustic emission study and strength analysis of crimped steel-composite joints under traction

Integrated in composite electrical insulators, metal/fibreglass-reinforced-plastic (GRP) joints made of an epoxy rod reinforced with E-glass fibres and of two crimped steel end-fittings are investigated numerically and experimentally. Numerical stress and strain distributions through the bond during the crimping phase and under an axial tensile test are calculated with a solid 3D finite element model and the damage initiation in the composite is highlighted. The simulations are compared to experimental data obtained from several joint specimens tested under pulling on an experimental set-up equipped with strain gauges and an acoustic emission system. Good correlation between the finite element predictions and the test results is found. The numerical and experimental study is also completed with a sensitivity analysis of the main geometrical parameters of the joints.

Stress and damage analysis of composite–aluminium joints used in electrical insulators subject to traction and bending

Numerical and experimental stress and failure studies are performed on metal/fibreglass-reinforced-plastic (GRP) joints used in composite electrical insulators consisting of an epoxy tube reinforced with E-glass fibres and of two aluminium fittings fastened to the tube with an adhesive. Subjected to traction and bending, the joints are modelled with axisymmetric 2D and solid 3D finite elements respectively. Numerical stress and strain distributions through the bond are calculated and the damage initiation in the composite is highlighted. The simulations are compared to experimental data obtained from several joint specimens tested on an experimental set-up equipped with strain gauges and an acoustic emission system. Good correlation between the numerical predictions and the experimental results is found.

高磁界下における液体窒素・ポリエチレンフィルム複合絶縁系の部分放電破壊

Electrical insulation is one of the important factors needed to realize superconducting power apparatuses. Some of the apparatuses have no magnetic field shielding due to the requirement of their construction, where the electrical insulation is exposed to high magnetic fields and/or high mechanical stress as well as cryogenic temperatures. However, electrical characteristics of the composite insulation system of coolant and polymeric film under magnetic field have not been reported even though it is a promising electrical insulation system for superconducting cables. This paper focuses on the effect of magnetic fields on partial discharge breakdown of a composite electrical insulation system of liquid nitrogen and polyethylene film. The experimental results show that the life-time of the film to electrical breakdown becomes shorter as the magnetic field increases up to 1 Tesla. This may be attributed to the change of partial discharge activities caused by the magnetic field.

Cryogenic radiation effects on electric insulators

The radiation allowable at the superconducting magnets of a fusion reactor may be limited by the radiation tolerance of organic and composite electrical insulators. The allowable dose at the magnets will in turn influence the thickness of shielding necessary and therefore the size of the magnets. The response of organic substances to radiation at 4 K cannot be confidently predicted from irradiations at higher temperatures. Therefore, epoxy-based, polyamide, and polyimide insulators chosen from superconducting magnet practice were irradiated in liquid helium to a total gamma dose of 20 MGy (2 × 109rd). Electrical resistivity was measured during and after irradiation and electrical breakdown was measured after irradiation. Mechanical properties measured at 77 K after irradiation included flexure strength, shear strength (of adheslves between copper), and compressive strength. Electrical properties were generally degraded, but the materials should still be useful as insulators. Mechanical strengths, however, were sufficiently decreased to require re-evaluation of some designs. Aluminized Mylar (superinsulation) was severely embrittled.

Intelligent Quality Assessment Of CompositeComponents For Electrical Applications

This work aims at the realization of an intelligent system for the quality evaluation of composite material electrical insulators made of a fiberglass/epoxy pultruded bar coated with silicon rubber. The system consists of two parts: (a) signal detection and analysis and (b) decision making through pattern recognition. A nondestructive evaluation technique based on the ultrasonic resonance testing method was chosen as signal detection system, and an artificial intelligence technique based on fuzzy logic reasoning was utilized for the development of the decision making support system.