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The layered permittivity graded material is achieved by making layered graded distribution of high permittivity fillers inside polymer matrix. In this study, we investigated the influence of the local electric field distortion by the high permittivity fillers on the surface field distribution of the layered permittivity graded material. In order to calculate the local field distortion of the high...
To achieve a lower permittivity solid insulator for HV power apparatus, we have developed a polymer composite filled with nanoporous silica particles. This paper investigated the influence of nanopore size of the nanoporous-silica particles on particle porosity and permittivity of nanoporous-silica/epoxy composite (NanoPC). NanoPC was prepared by mixing epoxy resin and four kinds of nanoporous-silica...
This paper investigated partial discharge characteristics in a closed void and void discharge deterioration characteristics of polypropylene (PP) films. It focused on the influence of film-surface structure (rough-surface and smooth-surface) on the deterioration characteristics. The partial discharge characteristic was evaluated by measuring PD patterns (phase-charge-number) under AC voltage application...
We have been investigating functionally graded materials (FGM) with the purpose of controlling and relaxing electric field in solid insulator of electric power apparatus. FGM is characterized by the spatial distribution of dielectric permittivity in a solid insulator, and can control the surrounding electric field distribution in power apparatus such as gas insulated switchgears (GIS) and epoxy mold...
Mesoporous-silica/epoxy composites consist of epoxy resin and the mesoporous-silica particles which have the micrometric particle-diameter and the nanometric pore-size. Mesoporous-silica/epoxy composite material can actualize nanoporous composite insulator. This paper presents the measurement results of specific gravity and dielectric permittivity for the mesoporous-silica/epoxy composites (MPC)....
In order to improve the accuracy of degradation diagnosis for CV power cables, it is important to clarify the inception and propagation mechanisms of electrical tree degradation from water tree degradation. This paper presents the influence of AC voltage prestressing on the inception voltage of AC electrical-tree in the deteriorated LDPE with dried water-tree. The experiment was carried out with a...
This paper presents an attempt to show the effectiveness of nanoporous-silica composite in epoxy matrix for voltage-endurance and lower permittivity by numerical analysis. By finite element analysis of the static electric field, we estimated the permittivity of the nanoporous-silica composite insulator required to reduce the electric field enhancement around the GIS solid spacer. In order to achieve...
In this paper, the simultaneous measurement of the space charge and conduction current were performed under constant DC field or increasing a dc ramp field to comprehend the breakdown phenomena of LDPE/MgO nanocmoposite. In the measurement under a dc constant field, the conduction current on LDPE increased clearly due to the positive charge injection by enhanced local field at the anode with negative...
This paper presents an attempt to derive the dielectric permittivity characteristics of polymer composite filled with the metal oxide particle which has mesoporous structure. Experiments were carried out on the epoxy composites filled with alumina microparticles which have the mesoporous structure (mesoporous-alumina/epoxy composites) with different particle content. Measurement of the specific gravity...
Breakdown characteristics of PPLP (Polypropylene laminated paper)® impregnated in liquid nitrogen (LN2) are presented. PPLP has three-laminated structure of kraft paper (KP), polypropylene film (PP film) and KP and has been used as an electrical insulating material in high-temperature superconducting cables. In this report, we investigated the influence of DC prestress on impulse breakdown strength...
To understand the space charge formation of low-density polyethylene (LDPE)/nano-sized magnesium oxide (MgO) nanocomposite materials, the breakdown strength and the space charge formation influenced by DC prestress were investigated. DC breakdown strength (Fb) of LDPE decreased with increase of DC prestress. A packet-like charge was observed under DC pre-stress. When the applied field turned to a...
The power module for the electrical vehicle needs electrical insulation material with high thermal conductivity. In this paper, we investigated the compatibility between dielectric breakdown strength and thermal conduction in epoxy/boron-nitride composite, in comparison with epoxy/alumina composite. The breakdown test was carried out under the application of dc lamp voltage and impulse voltage at...
Breakdown characteristics of PPLP (Polypropylene laminated paper) impregnated with LN2 for its application to high-temperature superconducting cable are presented. In this paper, we investigated the breakdown characteristics of PPLP, which was the three-laminated structure of kraft paper (KP), polypropylene film (PP film) and KP, in LN2 by comparison with those of the papers with different laminated...
To understand the space charge formation of low-density polyethylene (LDPE) / nano-sized magnesium oxide (MgO) nanocomposite materials, the space charge and the conduction current were simultaneously measured up to the breakdown under increasing DC ramp field. A negative charge was dominated in the sample without nanofiller (0 phr sample). A positive charge was dominated in nanocomoposite sample....
To develop a non-destructive observation system of electrical trees in electric components such as power modules, we used an acoustic microscope with a center frequency of 80 MHz to image electrical trees in a simulated sample. The fine structure of trees approximately 0.5 mm in size could be observed. The spatial resolution for trees via this measurement system was about 40–50 µm. Furthermore, image...
This paper presents an attempt to derive the dc dielectric breakdown characteristics of polymer composite filled with the metal oxide particle which has mesoporous structure. Mesoporous-alumina/epoxy composite was fabricated by compounding epoxy resin and mesoporous-alumina particles which had the micrometric particle-diameter and the nanometric pore-size. Measurement of the specific gravity of mesoporous-alumina/epoxy...
Stability of hydrophobicity of silicone rubber composites is considered to be important for long-term insulating performance of polymeric outdoor insulator. Recently, dynamic drop test (DDT), which could evaluate the stability of hydrophobicity under ac voltage application with good reproducibility, has been studied as a standard laboratory test in CIGRE. DDT could clear the time until the formation...
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