Mixed-frequency electric stress and the thermal issue by rapid semiconductor switching circuit topology cause unexpected insulation breakdown, indicating a key on medium-high frequency (MF-HF) transformers. This work focuses effects of temperature breakdown strength used epoxy resin insulation. An experimental method containing power supply measurement unit was constructed under high sinusoidal voltages with harmonic components. A continuous boost to induce dielectric breakdown. Meanwhile,...

Medium-frequency transformer (MFT) is an essential device in the smart solid-state (SST) prototype. Compared with well-defined principle design of magnetic core and windings MFT, insulation issues are barely concerned. This article focuses on improved optimization considering main strength structure. Dielectric breakdown characteristics epoxy resin insulating material were studied. An obvious reduction dielectric occurred at high frequency temperature thick samples, which used for clearance...

Diagnostic methods for fault location in cable insulation have become increasingly vital with the development of long-distance cables. This article presents an improved method based on complex reflection coefficient spectrum (CRCS). First, a mathematical model long high-voltage line consideration distribution-parameter circuit joints is established frequency domain, and CRCS analyzed. Next, principle domain reflectometry (FDR), algorithm time-frequency conversion which uses as analysis...

The XLPE insulations of three 110 kV AC cables with different manufacturers and operation histories two 160 DC before after the one-year prequalification test are studied in this paper. Slice samples taken from radial locations cable insulation layers by a circumferential peeling method measurements discharge current, dielectric spectrum VLF loss angle tangent carried out on inner, middle outer parts respectively. It is found that for under test, older is, more slowly current decays, greater...

Naringin (NG) has been proved to have numerous notable biological effects, including anti-inflammatory effect, anti-cancer and anti-ulcer yet there are no clinical preparations of naringin due its poor solubility low dissolution rate after oral administration. In this study, in order overcome these problems, NG was encapsulated into MPEG-PCL micelles (NGMs) by using a thin-film hydration method. NMGs were typical core-shell structure, with mall particle size (23.95 ± 0.51 nm), high drug...

The spiral corrugated aluminum sheath is most commonly used in HV XLPE land cables China. In recent years, cable faults caused by discharge ablation of semi-conductive buffer layer below the have been frequently reported, and a large scale traces on insulation screen surface found dismantled cables, which has aroused widespread concern. this paper, after brief summary kind failure phenomena, theoretical experimental researches cause mechanism are provided, with relevant conclusions listed....

The ablation failures of the water-blocking buffer layer in HV XLPE cables have occurred frequently, causing widespread concern industry. In this paper, a 220 kV faulted cable was dissected to observe distribution and characteristics points, samples white substance were taken from points be tested by Fourier transform infrared spectroscopy scanning electron microscope energy disperse spectroscopy. At same time, simplified experimental device set up simulated experiments conducted reproduce...

The insulation of high-frequency transformers (HFTs) has a significant impact on the safety and reliability high voltage power electronic (PETs). transient voltages from rapid turn-off turn-on semiconducting device increase stress loss, resulting in thermal distortion. However, few studies have presented an accurate evaluation dielectric especially under dV/dt square waves. This paper focuses loss calculation HFT by analyzing wave with spike voltages. A step function that is equivalent to...

An exploration of discharge efficiency and uniformity improvement by using pre-ionized bipolar pulse method in dielectric barrier (DBD) device under atmospheric pressure is conducted. Through utilizing the charged particles on surface, amplitude applied pulses for sustaining can be significantly decreased. By analyzing influence “built-in” electric field from surface charges uniformity, a scheme proposed. Since property closely dependent with parameters, such as amplitude, number, polarity,...

In this paper, the voltage, electric field, and dielectric loss of high frequency transformer used in power electronic are studied. According to finite element method (FEM), influence voltage harmonic components on field distribution were calculated. The results show that winding ground is greater than terminal at top module cascade structure. Moreover, former contains lots order harmonics. insulation between windings suffers from nonsinusoidal periodic voltages with multi-harmonics....

Natural ester as an environmentally friendly dielectric liquid is becoming commonly used in power transformer. However, it susceptible to oxidation. Under severe oxidation, the oil sample could gel whose impact on insulation performance not known. In this research, we focus of gelling process natural its breakdown characteristics. order survey this, a test platform was first assembled. Then experiment conducted, with results showing that procedure includes three stages, liquid, sol and gel....

This paper is dedicated to illustrate the frequency dependence of breakdown strength epoxy resin insulation used in solid state transformer. The experimental protocol was developed measure voltage film, including high power supply (up 20 kV), measurement and detection units. output can be reached 10 kHz. Weibull distribution statistics analysis employed discuss influence on characteristics resin. dielectric indicates a reduction with increase electric stress. Moreover, data dispersion...

Cable accessories are the weakest parts in whole cable system. The performance matching of insulating materials on interface is very important, and same important smoothing insulation surfaces. surface smoothness depends peeling techniques applied site a less well-controlled environment. effect XLPE electrical treeing characteristics at XLPE-SIR was investigated this paper. SIR samples were pressed together under different interfacial pressures by specific pressing device, with sample...

In recent years, high voltage (HV) cross-linked polyethylene (XLPE) cable with corrugated aluminum sheath has suffered frequently from ablation failures of water-blocking buffer layer in China, which causes wide attention to both the failure mechanism study sheathed cables and product development smooth composite cables. One key technologies for is firmly bond outer serving by hot melt adhesive ensure bending resistance. Therefore, on mechanical characteristics bonding interface great...

Bipolar charge transport (BCT) model is widely accepted to describe dynamics in low-density polyethylene (LDPE) and its nano-composites, which gives a relatively reasonable explanation of experimental results including concentration external current density. However, existing simulations are faced with several unavoidable obstacles. Carrier mobility, trap cross-section recombination rate not theoretically represented as constants due strong influence temperature. When the...

XLPE and silicone rubber (SIR) have been widely used in power cables accessories for their excellent mechanical electrical performance. However, the interface between them remains one of weakest parts cable system. Electrical treeing is an important destructive factor HV insulation structures, it always leads to final breakdown. Therefore, essential investigate effects interfacial pressure on tree. In this paper, tests were carried out by pressing SIR samples together under different...

XLPE and silicone rubber (SIR) have been widely used in power cables accessories for their excellent mechanical electrical performance. However, the interface between them remains one of weakest parts cable system. Electrical treeing is an important destructive factor HV insulation structures, it always leads to final breakdown. Therefore, essential investigate effects interfacial pressure on tree. In this paper, tests were carried out by pressing SIR samples together under different...

Various sources of information are available for identifying and evaluating adverse drug reactions (ADRs). However, some studies only used the ADR data from spontaneous reporting databases to evaluate safety post-marketing drugs. This study was performed identify an appropriate method drugs by comparing frequencies ADRs among three datasets: randomized controlled trials, published case reports, reports. Taking fluorouracil as example, we collected types extracted their information. All...