The unclear understanding of the water diffusion behavior posts a big challenge to manipulation absorption properties in epoxy resins. Herein, we investigated and its relationship with molecule structures inside an resin mainly by nonequilibrium molecular dynamics experiments. It is found that at initial rapid stage, bound free both contribute, while later slow plays dominant role. observed evolution cannot be explained traditional Langmuir model. In addition, polarity, volume, segment...

By mimicking the layered structure of nacre, we successfully fabricated a nano-laminar coating on high-voltage insulators. The is demonstrated to achieve higher flashover strength by effectively dissipating surface charge under dc stress.

Power cables operate at high temperatures over long periods of time, and the electrical behavior silicone rubber (SIR) in new types extra-high-voltage prefabricated cable accessories would change as a result thermal aging. In this study, tests were conducted to reveal effects aging (1000 h 60–180°C) on treeing behavior. It was found that with increasing average tree initiation voltage (ATIV) SIR initially increases peak value then decreases, finally becoming stable within 1000 h. Meanwhile,...

In this work, positive temperature coefficient (PTC) material, as a functional filler to compensate the negative of DC electrical resistivity epoxy resin, is studied. As rises above Curie temperature, PTC material increases composites when compared neat epoxy. At 110°C, found be 252.6% Dielectric spectroscopy used analyze mechanism on composites. This paper shows that has potential regulate resistivity-temperature characteristic polymeric insulating materials.

Electrical property parameters are crucial elements in the design of cable accessories, emphasizing significance precisely understanding their operational characteristics. This study investigates variations electrical properties silicone rubber (SR) insulation under mechanical stretching. The distribution characteristics relative permittivity and AC breakdown strength determined based on stretching state. Furthermore, electric field safety margin calculated to assess capability accessories....

In this paper, initiation behaviors of DC electrical tree in silicone rubber were studied under different voltage polarities and temperature gradients (temperature needle ground electrodes ranged from 20 to 120 °C). Electrical probability, shape, length obtained via the statistics. The results show that polarity effects, where positive is easier for trees initiate, appear evidently various situations. As gradient, decreases first then returns a larger value with increasing when electrode...

Electric field stress concentration is one of the causes partial discharge (PD) in power modules, which threatens modules' safe operation. Herein, this article investigates influences temperature (from 150 to <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$250~^{\circ }\text{C}$ </tex-math></inline-formula> ) and operation duration on maximum electric at triple point (silicone elastomers, ceramic, copper)....

In this article, the electrical tree initiation behavior in silicone rubber (SIR) under DC voltage was studied. Tests were conducted to reveal effects of temperature (20-120°C), defect type and polarity on initiation. samples with an undamaged needle-tip (N samples), we find that average (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ati</sub> ) decreases exponentially increasing by 42%. Single-branch trees multiple-branch are observed. The...

Electrical tree aging problem under high-frequency voltages seriously affects the reliability of packaging insulation for power electronics modules. In this article, boron nitride (BN) sheet/epoxy resin (ER) composites with low doping concentration are prepared and characterized. Varied voltage frequencies (50 Hz–130 kHz) selected, electrical characteristics at different studied. Results show that as frequency increases from 50 Hz to 130 kHz, initiation pure ER decreases by 39.8%. However,...

Abstract Electrical tree degradation is one of the main causes insulation failure in high‐frequency transformers. studied on pure epoxy resin (EP) and MgO/EP composites at frequencies ranging from 50 Hz to 130 kHz. The results show that initiation voltage EP decreases, while growth rate expansion coefficient increase with frequency. Moreover, bubble phenomenon high discussed. Combined trap distribution characteristics within material, intrinsic mechanism inhibit electrical different It can...

Power cables are widely used in various fields of power transmission, and cable accessories the weakest link systems due to their complex structure multi-layer insulation coordination issues. This paper investigates changes electrical properties silicone rubber/cross-linked polyethylene (SiR/XLPE) interface at high temperatures. The physicochemical XLPE material under thermal effects with different times characterized through FTIR, DSC, SEM tests. Finally, mechanism state on SiR/XLPE is...

Adding nucleating agents (NAs) is one of the most efficient ways to obtain improved mechanical, optical, and thermal properties isotactic polypropylene (iPP). While it well appreciated that electrical property critically affected by crystalline modification, role between them remains unclear. Here, we address this issue incorporating commercial α-NA β-NA into iPP, both which exhibit strong nucleation ability, e.g., reducing size agglomerates from 45.3 μm (Pure-iPP) 2.5 (α-iPP) 7.6 (β-iPP),...

Low-density polyethylene (LDPE), as an excellent dielectric insulating material, is widely used in electrical equipment insulation, whereas its low thermal conductivity limits further development and application. Hexagonal boron nitride (h-BN) filler was introduced into LDPE to tailor the properties of make it more suitable for high-voltage direct current (HVDC) cable insulation We employed melt blending prepare h-BN/LDPE thermally conductive composite materials with different contents....

Nano-size positive temperature coefficient (PTC) ceramic particles and epoxy composites doped with 0, 0.5, 1, 5, 10 20 phr of PTC nanoparticles are prepared to suppress the decrease electrical resistivity temperature. Electrical under 30, 50, 70, 90, 110 °C, DC breakdown strength, trap characteristic measured. electric field distribution radical gradient is simulated using a simplified bushing model insulated materials. The mechanism for regulating resistivity-temperature discussed. at...

In comparison with the AC and DC working voltages, effect of switching impulse voltage on insulation is very different because its fast-rising rate large amplitude. This paper mainly focuses characteristics PD in oil-impregnated under voltage. First, a robust experimental platform was set up including power source, test samples uniform gas oil gap, signal acquisition processing system. air gap are analyzed compared involving time-domain waveforms, variation tendency average amplitude numbers...