Abstract Solid‐state transformers (SSTs) have applications in medium‐voltage direct current (MVDC) grids and compact power systems. High‐frequency transformer (HFT) is the core component of SSTs. High levels high frequency d v /d t voltage stresses challenged integrity galvanic insulation HFTs. However, dielectric thermal runaway resultant electrical failure mechanisms epoxy resin (EP) cast remain unclear. Dielectric heating EP across varying voltages, frequencies, rising edges, duty cycles...

Gas-insulated switchgear (GIS) is widely used today in electrical power systems because of its reliability, compaction, long maintenance cycle, and small impact on the environment [1]. In use normal operation disconnector generates very fast transient overvoltages (VFTO) with frequencies ranging from 1 to 100 MHz [2] amplitudes up 2.5 p.u. [3]. For above 330 kV, insulation strength GIS under VFTO concern as failures caused by have exceeded those lightning impulse (LI) [4]. This...

A pseudospark-sourced electron beam is a promising candidate for driving THz millimeter wave radiation source. However, the physics governing density profile and center deviation from axis of structure, which may be caused by randomness in pseudospark discharge process, remains still unclear especially high energy component beam, usually non-mono-energetic. It essential to study position distribution optimizing configuration. In this paper, images some single-shot pulses have been captured...

The discharge characteristics of SF6 dependent on gas pressure under extremely inhomogeneous electric fields are strongly nonlinear and must be carefully considered when optimizing gas-insulated equipment insulation design defect detection. main aim this study was to determine the relationship between breakdown pre-breakdown mode transition. model established by Niemeyer, as adapted impulse voltage, expanded. images phase-resolved patterns a function applied voltage were analyzed observe...

In order to clarify the features of pre-flashover and predict ice flashover more accurately, entire evolution leakage current during process both AC long short suspension insulator strings covered with were recorded analyzed in this paper. It is found that processes ice-covered could be divided into four stages based on time domain characteristics current. Two significant parameters proposed as characteristic for analysis characteristics, namely (IW) which was quasi-constant value Stage III,...

From field experience and laboratory experiments, it was indicated that the flashover performance of contaminated insulators significantly influenced by insulator geometry. In paper, with three different profiles including seven types deep under-ribs disc insulator, two-shed three-shed were tested in an artificial climate chamber to investigate influences profile parameters on large tonnage insulators. The contamination test results 50% voltage stress (E <sub...

Flashover of contaminated insulators is one the major problems for power distribution. Laboratory experiments have shown that arc characteristics great influences on study flashover performance insulators. In order to investigate AC discharge polluted insulation surface, an experimental system was designed. The emission spectroscopy obtained by a CCD spectrometer, and lithium chloride added in artificial pollution introduce as indicator element analysis spectroscopy. Arc temperature...

It is an important way by detecting SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition products to evaluate the insulation condition of insulated power equipment. In this paper, N xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> &Ni doped 555-777graphene (N &Ni-graphene) proposed as a new gas sensor detect characteristic components products: H xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> S, SO , SOF and F . order...

Adiabatic temperature variation (ΔT), coefficient of performance (COP) and electrocaloric (ΔT/ΔE) play important roles in evaluating the comprehensive solid-state cooling technology based on effect (ECE). A Nb Sn co-doped lead zirconate titanate antiferroelectric film, Pb0.99Nb0.02(Zr0.85Sn0.13Ti0.02)O3 (PNZST), shows a highly efficient giant negative ECE. The ΔT, |ΔT/ΔE| COP are about -9.8 K, 0.0488 K cm kV-1 35.53 at around 50 °C, respectively. full width half maximum ΔT peak is 37 °C....

To research discharge physics under AC voltage, a phase synchronization photography method is presented. By using permanent-magnet synchronous motor to drive mask synchronized with power supply, images in specific window can be recorded. Some examples of discharges photographed by this method, including the corona SF6 and along air/epoxy surface, demonstrate feasibility method. Therefore, provides an effective tool for researchers.

<title>Abstract</title> The long-term operation performance of HVDC transmission systems is significantly influenced by the reliability thyristors. However, current research thyristors mainly based on leakage and there no comprehensive degradation characteristics In this article, under voltage temperature accelerated ageing tests are obtained, including reverse recovery characteristic, on-state blocking characteristic gate characteristic. obviously degrades tests. charge time decrease over...

The long-term operation performance of HVDC transmission systems is significantly influenced by the reliability thyristors. However, current research thyristors mainly based on leakage and there no comprehensive degradation characteristics In this article, under voltage temperature accelerated ageing tests are obtained, including reverse recovery characteristic, on-state blocking characteristic gate characteristic. obviously degrades tests. charge time decrease over 10% after Seven operating...

High-Frequency Transformers (HFTs) are subjected to different types of voltage stress, including DC or AC grid and high-frequency square wave voltage. As the demand for higher ratings greater compactness HFTs continues rise, insulation strength resin cast solid becomes a crucial factor in design HFTs. This study investigated difference breakdown (BDV) under various types, obtained BDV specimens with installation polarity, analyzed influence duty cycle unipolar wave. Additionally, dynamic...

Nonpolar ZnO films are deposited on (100) Si substrate using LaNiO 3 conducting buffer layer by radio frequency sputtering. X-ray diffraction results show that (110) and (002) orientation with without layer. The current behavior of ZnO/LaNiO heterojunction exhibits ohmic conduction which is different from the diode-like rectification film insulated layers. photoluminescence properties indicate (110)-oriented nonpolar has better band-edge emission than (002)-oriented polar film. It suggested...