The dielectric loss characteristics of epoxy resin, as a critical insulating material in high-frequency transformers, are essential to the performance and safety transformers. This paper explores mechanism epoxy/anhydride curing systems through molecular dynamics simulations, particularly focusing on impact segmental motion loss. study reveals that probability density distribution speeds various segments cross-linked network follows Maxwell-Boltzmann distribution. increased rigidity agent...

Operating experience shows that residual DC voltage remains in GIS bus bar for a long time after opening of disconnectors. This will not only cause accumulation charges and contaminants on the insulator surface, but also easily lead to motion free metallic particles SF6 gas gap, weakening insulation ability GIS. At disconnectors reclosing, impulse could be generated superimpose pre-existing voltage. As result, under combined impulse. paper experimentally studies characteristics lightning It...

The safety and stability of power systems are seriously threatened by the decay-like fracture composite insulators. This paper analyzes aging characteristics (physical properties, NMR, FTIR) silicone rubber sheds fractured insulator. same V-string insulator a new used for comparison. study shows that sheds’ degradation is concentrated on side with heavy pollution. physical properties (appearance, pollution, hardness, hydrophobicity) high voltage end decrease significantly compared to other...

The power outage caused by decay-like fracture of composite insulators significantly impacts the grid. In this paper, a fractured insulator 500 kV transmission line is taken as research object. detailed observation core rod and silicone rubber housings, discharge results, temperature rises, electric field distribution are obtained. (a) has abnormal heating on exposed sheath surface, ambient humidity influence rise. (b) It proposed that one most obvious characteristics rise (such T > 50°C, ΔT...

Contamination of free conducting particles is a major threat to gas insulated systems. In HVDC GIL, can be even more harmful due the fact that easily cross gap under DC voltage and distort electric field. systems, impulse overvoltage generated superimposed on operating voltage. As result, GIL will experience this paper, behavior in observed breakdown characteristics particle contaminated voltages are studied. Two motion patterns mainly found: bouncing firefly motions. Particles tend near...

The past and recent investigations show that front time of switching overvoltage waveforms in Ultra High Voltage (UHV) system long distance transmission are mostly wave exceeding 1000 μs. impulse voltage has been deviated from the critical time. This paper is involved with breakdown characteristics external insulation design under UHV system. All Tests were performed on an outdoor test site at altitude 2100 m, China Southern Power Grid Co. Ltd. (CSG). Breakdown rod-plane actual size...

A large density difference of a basin-type insulator in gas-insulated metal-enclosed switchgear (GIS) weakens its mechanical strength, which will threaten the safe and stable operation GIS. In this article, an ultrasonic nondestructive testing method for uniformity GIS insulators was proposed. First, seven standard samples with different Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O...

Thermal stress of gas-insulated metal-enclosed switchgear (GIS) basin-type insulators weaken its mechanical properties, which will threaten the safe and stable operation GIS. In this article, simulation experiment thermal in a 252-kV GIS insulator were carried out. An acoustic-distance difference method based on ultrasonic critical refraction longitudinal wave (ultrasonic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math...

The multifactor accelerated aging test is an important means to predict the lifetime of gas-insulated switchgear (GIS) O-ring seals, while leakage rate (LR) a potential index for failure evaluation. This article proposed three-factor platform and system (LTS) GIS seal rings. factors are thermal, mechanical compression, pressured SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. pressure vessel (PAV) can be filled with various gases...

This paper deals with the air gap insulation of ±800 kV DC transmission systems under composite and switching impulse voltage. The gaps studied were representative line, as rod-to-plane conductor-to-tower gaps. flashover voltages at an altitude 2100 m determined for a pure impulse. It is found that there are clear increase in voltage both gaps, compared those only was applied. From test results, increases by 17-23%in 5-10% gap, when 800 pre-stressed. standard deviations have little obvious...

In this work, we propose an all-dielectric frequency selective surface (FSS) composed of periodically placed high-permittivity dielectric resonators and a three-dimensional (3D) printed supporter. Mie resonances in the offer strong electric magnetic dipoles, quadrupoles, higher order terms. The re-radiated fields by these multipoles interact with incident fields, which leads to total reflection or transmission some special bands. measured results fabricated FSS demonstrate stopband...

The chalking of composite insulators is referred to a kind abnormal aging the silicone rubber sheds.It has serious adverse effects on long-term operation insulators, but mechanism behind its generation and development remains unclear.In order deeply understand phenomenon insulator chalking, this paper took chalked operating extra-high voltage (EHV) AC 500 kV as samples for research.Appearance inspection, hydrophobicity test tensile stress were performed determine change their surface...

In order to further utilize the transmission line cooridor, meanwhile, achieve a relatively friendly electromagnetic environment, composite cross arm is developed and employed in system. The electric field distribution as well electromagentic environment of deserves detailed in-depth study verify its performance. this research, three-dimension (3D) finite element method (FEM) was calculate arm. characterized by intensity on ground, radio interference audible noise these parameters were...

As one of the key components circuit breaker operating mechanism, relay can experience performance degradation due to harsh environmental factors, such as salt spray, during operation, which ultimately affect normal operation and threaten safe stable power system. To effectively evaluate condition in spray environments over long term, this study conducted accelerated aging experiments on a certain model auxiliary switch under conditions using an existing test platform. The relay’s pull-in...