In this paper, we studied on permissible current of unperfected earthing for cross-bond system. The factors of unperfected earth were jacket damage, cross-bonding mistake, arrestor damage, effect of other circuit but we only studied permissible current of arrestor or jacket damage. In the result, we earned that permissible current of normal 154[[kV]] CV $1C{\times}400SQMM$ cable is 760[A] but current of unperfected earthing cable is 76[A], unperfected earthing confirmed that accident of underground cable could occur. So, we could confirmed that Earthing resistance of unperfected earthing need to limit.

This paper presents the electrical properties of PTFE nozzle for a electrical apparatus. In the arcing environment in a electrical apparatus, radiation is considered to be the major energy transport mechanism from the arc to the wall. The fraction of the radiation power is emitted out of the arc and reaches the nozzle wall, causing ablation at the surface and in the depth of the wall. The energy concentration in the material leads to the depolymerization and eventually leads to the generation of decomposed gas as well as some isolated carbon particles. Adding some fillers into PTFE is expected to be efficient for improving the endurability against radiation. In this experiment, three kinds of fillers that have endurance in the high temperature environment were added into PTFE. Light reflectance of fillers was investigated. Dielectric constan and dissipation factor of PTFE composites were investigated. Dielectric constant and dissipation factor of the PTFE composites increased with increasing contents of the fillers.

In this paper, the effect of adhesion properties of semiconductive-insulating interface layer of silicone rubber on electrical properties was investigated. The modifications produced on the silicone surface by oxygen plasma were accessed using ATR-FTIR, contact angle and AFM. Adhesion was obtained from T-peel tests of semiconductive layer having different treatment durations. In addition, ac breakdown test was carried out for elucidating the change of electrical property with duration of plasma treatment. From the results, the treatment in the oxygen plasma produced a noticeable increase in surface energy, which can be mainly ascribed to the the creation of O-H and C=O. It is observed that adhesion performance was determined by not surface energy but roughness level of silicone surface. It is found that ac dielectric strength was increased with improving the adhesion between the semiconductive and insulating interface.

피뢰기에 뇌 또는 이상전압과 같은 정격이상의 고장전류가 유입되어 발생하게 되는 순간적인 열 충격과 내부압력 상승은 폭탄이 내부에서 터지는 것과 같은 엄청난 양의 충격에너지이다. 본 연구에 있어서 폴리머 피뢰기의 제조에 사용된 모듈용 브레이드 복합재료는 압력해소 및 폭발 비산하지 않도록 하는 기능을 수행하도록 설계되어있다. 기존의 폴리머 피뢰기에 적용된 복합재료보다 충격에너지를 흡수하는 구조물에 유리한 브레이드 복합재료를 피뢰기 모듈의 제조에 도입한 것은 매우 의미 있는 일이라 판단된다. 따라서 본 연구에서는 열경화성 브레이드 복합재료를 제조하기 위하여 프리폼을 먼저 제작한 다음 금형에 삽입한 후 진공상태에서 수지를 주입하여 경화시키는 RTM공법을 이용하였다. 본 연구의 목적은 브레이드 패턴 및 방압개소 설계 등의 기초적인 자료조사 및 실험을 통하여 폴리머 피뢰기의 폭발 비산을 방지할 수 있는 압력해소 성능을 위한 기초 자료를 확보하고자 하는 것이다. 브레이드 복합재료의 기본적인 경화거동을 등온 및 동적 DSC를 이용하여 고찰하였고, 기본적인 전기적 특성을 평가하였으며, 방압개소를 가진 폴리머 피뢰기 모듈의 고장전류시험시 예상되는 열 충격에 대한 성능을 검증하기 위하여 열팽창계수를 측정하였다.

The resonant planar transformer, which had power capacity of 300 W, input voltage of 220 V, output voltage of 15 V, and switching frequency of 500 kHz, was designed and manufactured by using the planar core with large effective area and the flat copper lead frames for miniaturization and high efficiency of the switching mode power supply (SMPS). As well as, a resonant converter equipped with the above mentioned planar transformer was manufactured and electromagnetic characteristics were investigated. The numerical value of turns for 1st and 2nd winding were 12 and 2 respectively. The self inductance of 1st winding was 33.2 ${\mu}H$, very low leakage inductance of 1.27 ${\mu}H$, and the coupling factor of 0.98 were obtained at switching frequency of 300 kHz. The high efficiency of 88.21 % for the SMPS equipped with planar transformer was obtained at power capacity of 300 W.

Corona on polymer materials causes deterioration by the combined action of the discharge striking the surface and the action of certain chemical compounds that are formed by the discharges. In the design and manufacture of polymer insulators must be sufficiently large to avoid corona discharges, otherwise a shielding or corona ring (grading ring) needs to be installed on the insulator. To conduct this purpose, many researchers have investigated end-fitting of polymer insulator by voltage distribution simulation and electrical test. Grading rings are used to improve the performance of the insulator in multiple ways. They can reduce corona and associated audible noise and radio influence and television interference. The factors determining the uses of a grading ring are line voltage, geometry and dimensions of end fittings, geometry and dimensions of line hardware, and environmental conditions. In this paper, electrical property of polymer insulator with end-fitting design have been investigated by electrical field analysis, various end-fitting design, tracking wheel test, corona inception voltage and extinction voltage. Electrical field analysis is conducted by FEM program and various end-fitting is designed through this result. Designed end-fittings are manufactured and their performance is conducted by electrical performance test.

A surge counter is installed under surge arrester, which is protecting the power system apparatuses against abnormal voltage and surges originated in power system line. A surge counter is the device of knowing the times of surge flowed in. There are two methods to get the electric power for mechanical movement and detect the surge. One is using ZnO varistor resister and the other is using the current transformer. In this paper, the characteristics of these methods are presented with using the test and evaluation of them. The process of evaluating the characteristics is essential to develop the domestic surge counter.

It is well known that Ag-CdO alloy for electrical contactor has been widely used in weak or middle electric current field. But it is necessary to decrease Cd contents without decrease of contactor property because Cd is harmful to human body. The present work has been carried out to investigate effects of Mm (misch metal) addition on the property of Ag-CdO alloy for electrical contactor. As the results of present works, hardness and strength was improved and arc resistance was improved, also, in spite of decrease Cd contents by the Mm addition. It was estimated that Ag-oxide particle was refined by Mm addition.

In this research, we used discharge tube without dielectric bead or with dielectric beads($SiO_2$, $Al_2O_3$, or $ZrO_2$), and discharge in water for removal of Escherichia coli. At the result of experiments, the removal characteristics of Escherichia coli appeared relation ratio to input voltage. Because, the electric field of discharge tube is increased when input voltage is increased. And, discharge tube used dielectric bead($ZrO_2$), the removal characteristics of Escherichia coli was better than cases of else.

Recently many research activities on the diagnosis of stator winding insulation of high-voltage motors have been reported. Most of them utilize a trend analysis of partial discharges. In this paper, a novel on-line monitoring system for an insulation diagnosis is proposed. This system displays magnitude and phase angle distribution of partial discharge. The partial discharge activities can be interpreted more precisely by these techniques.

The paper shows that the combination of the hardware, NI PCI 6110E board and the software, Fourier and continuous wavelet transform(CWT) can be used to implement for extracting the important features of the real-time signal. The results confirmed that CWT produces the fast computation enough for the application of the real-time signal processing except the negligible time delay. In denoising case, because of the lack of translation invariance of wavelet basis, traditional wavelet thresholding leads to pseudo-Gibbs phenomena in the vicinity of discontinuities of signal. In this paper, in order to reduce the pseudo-Gibbs phenomena, wavelet coefficients are threshold and reconstruction algorithm is implement through shift-invariant gibbs free denoising algorithm based on wavelet transform footprint. The proposed algorithm can potentially be extended to more general signals like piecewise smooth signals and represents an effective solution to problems like signal denoising.

Electrical arc is the final stage of insulation breakdown and has high current density which cause heat and light in insulator. Insulator under electrical arc lost its insulating strength and eternal damages. Conventional criterion of electrical arc resistance in Standards have depended on the change of sound pressure and light color after damages on insulator by electrical arc. The recognition of these changes is done by human himself which was very subjective and resulted in some error to judge whether insulator has damages or not. This paper has shown that antenna method is the appropriate measure to judge electrical arc resistance for insulator. Antenna measures the electromagnetic waves radiated from tungsten electrodes with 6mm gap regulated by KSC2130. Applied voltage cross two tungsten electrodes have two different methods such as 1/8 10 and continuous 10mA. Signal amplitudes obtained by antenna has diminished after the damage of insulator, which will provide objective and good way to judge the electrical arc resistance.

Recently, the RF inductive discharge or inductively coupled plasma (ICP) continues to attract growing attention as an effective plasma source in many industrial applications, the best known of which are plasma processing and lighting technology. To the point of lighting sources, the electrodeless fluorescent lamps utilizing an inductively coupled plasma (ICP) have been objects of interest and research during the last decades, mainly because of their potential for extremely long life, high lamp efficacies, rapid power switching response. The electrodeless fluorescent lamp that is dealt with in this work comprises a bulb filled with rare gas and amalgam of vaporizable metal and has a coil provided with a winding around the ferrite. Current through a coil produces a magnetic field in the discharge space. The changing magnetic flux then produces an azimuthal electric field E around the coil, according to Faraday's laws of magnetic induction.

This paper researched leakage current characteristics of artificially contaminated EHV insulators through construction of long-term testing facility. Insulators were contaminated and classified into the ESDD contaminated levels under IEC standards method. As the test results of contaminated insulators was carried out several experiments, leakage current greatly increased during initial rainfall. After contaminated insulators were naturally washed by rain, leakage current was not increased.

In recent, there have been several developments in lamp technology that promise savings in electrical power consumption and improved quality of the lighting space. Above all, the advantage of ring-shaped electrodeless fluorescent lamp is the removal of internal electrodes and heating filaments that are a light-limiting factor of conventional fluorescent lamps. The ring-shaped electrodeless lamp is intended as a high efficacy replacement for the incandescent reflector lamp in many applications. Therefore, the life time of ring-shaped electrodeless fluorescent lamps is substantially higher than that of conventional fluorescent lamps and last up to 60,000 hours. In this paper, we present measurement results of electrical characteristics of a ring-shaped electrodeless fluorescent lamp as a function of frequency and number of coil turns using a highly permeable Mn-Zn ferrite. It is found that the impedance are increased while the quality factor decreases as frequency increases.

Resistive leakage current following arresters is an important indicator of ageing, but total leakage current and its harmonic analysis are widely used in diagnosing arrester soundness because of difficulties in measuring resistive leakage current. In this paper, we proposed a new method for measuring resistive leakage current, which is quite different from the conventional methods such as a self-cancel method and a synchronous rectification method. The proposed method is based on that the magnitudes of resistive leakage currents are equal at the same voltage level. To confirm the possibility of the proposed method. we fabricated a leakage current measurement device and designed an analysis program that can analyze resistive leakage current. Comparing with other methods. this technique does not need a complex circuitry and is very simple to complete.

This paper presents the results of spectral analysis of leakage current waveforms on contaminated insulators under various fog and environment conditions(salt fog, clean fog, rain) The larger the leakage current during 200ms, the higer the power spectrum at 60Hz. For almost equal maximum current during 200ms, however, the spectrum at 60hz and the odd order harmonics increase emphatically when discharges occur continuously for several half-waves. If contaminated insulators suffers from high salt-density fog, the leakage current occurs with high crest value intermittently, results in the low spectrum. Analysis of leakage current data showed that this electrical activity was characterized by transient arcing behavior contaminants are deposited on the insulator surface during salt fog tests. This provides a path for the leakage current to flow along the surface of the insulator. It is important to have an indication of the pollution accumulation in order to evulate the test performance of a particular insulator. If the drop in surface resistivity is severe enough, then the leakage current may escalate into s service interrupting flashover that degrade power quality.

This research is about the result of leakage current waveform about the situation of surface leakage current and environmental changes(Salt fog, clean fog and rain) by EPDM polymer insulators' amount of salt. The researcher presents the result of changing about fundamental harmonic, 3rd harmonic and 5th harmonic from starting point of supplying power to flashover. In this study, researched environmental affects (clean fog, salt fog and rain) about surface aging of polymer insulators and used frequency spectrum of leakage current waveform to develop the diagnostic technique of surface aging. When amount of salt contents changed, surface aging stage and the degree of aging (distortion factor) about 3rd and 5th harmonic waveform on low frequency harmonic wave. The distortion factor which is harmonic percentage about basic harmonic is important pointer to evaluate the surface condition of polymer insulators.

Laminated Polypropylene Paper (LPP) and Kraft paper were used as ac power insulation for conventional cable as well as high temperature superconducting (HTS) cable because of its prominent insulating characteristics. However, researches on the use of LPP/Kraft paper in HTS cables are thinly scattered. In this paper, the effect of laminate polypropylene paper on the breakdown strength of LPP/Kraft multi-layer sample impregnated with liquid nitrogen (LN2)under ac and impulse applied voltage was studied. In addition, the breakdown strength characteristics of LPP and Kraft multi-layer sample were also investigated. It was found from the experimental data that the LPP has higher breakdown strength value than Kraft paper in ac and impulse. Especially in the ac case, the breakdown strength increases as the component ratio of LPP in the LPP/Kraftsample increases and slightly affected by the inserting position of LPP but in impulse case, the breakdown strength strongly depends on the number of LPP and the relative position of LPP.

This paper presents experimental data from model windings with different arrangement of coil in order to provide information to design a 22.9 kV class HTS transformer. Before experiment, the composite insulation of two different type of HTS transformers are investigated. The first basic of investigation is a breakdown characteristic of liquid nitrogen and flashover characteristic on the GFRP surface under ac and impulse, The second investigation is insulation design, manufacture and test of model windings. These include a AC withstand voltage test of 50 kV rms and a lighting impulse test of 150 kV at peak.

In this paper, BP learning algorithm is studied to apply as a PD source classification in GIS specimens. For occurred partial discharge, three defected models are made; floating particle, surface discharge of spacer, needle to plane. And PD data for discrimination were acquired from PD detector. And these data making use of a computer-aided discharge analyser, statistical and other discharge parameters is calculated to discrimination between different models of discharge sources. And also these parameter is applied to classify PD sources by neural networks. Neural Networks has good recognition rate for three PD sources.

The effect of magnetic field was measured on NOx removal for cylinder-wire plasma reactor with magnetic field applied to electric field vertically. Power was supplied to plasma reactor using rotating spark gap switch. Consumption power increased with increasing discharge voltage. When magnetic field was applied to electric field vertically, consumption power was less than that without magnetic field because of lorenz's force. NOx removal rate of plasma reactor with magnetic field were higher, 10-15%, than that of plsama reactor without magnetic field. And NOx removal rate decreased with increasing gas flow rate.

In this paper, the NO was oxidized NO2 by using the non-thermal plasma and NOx removal characteristics were measured by showering NaOH water-solution to NO2. The NO oxidation increased as the order of DC, AC, and Pulse. NOx oxidation for two stage with applied voltage was better than that for one stage with applied voltage. NOx oxidation didn't depends on applied voltage. While NO oxidation was going, NOx removal efficiency was 20-25%, however, significantly depended on injection method of air and H2O+air. When NaOH water-solution density of 20% was showered to flue gases, NOx removal efficiency increased to 65%.

This paper is investigated about the effect of vibration of the water surface for hydrogen gas generation by non-thermal plasma. The vibration of the water surface is more powerful with increasing applied voltage. In this experimental reactor which is made of multi-needle and plate, the maximum acquired hydrogen production rate is about 6.8[ml/sec]. Although the generation of hydrogen gas is increased with elevating time, it is saturated after specific time due to the volume of reactor and the saturation of taylor cone.

The protection performance and energy absorption capability are important for both MOAs for distribution lines and MOAs for high voltage systems, therefore the manufacturing technique of ZnO varistor elements with high ability against surge impacts is great important for high voltage systems. But until now ZnO varistors for low voltage class have been developed in Korea, ZnO varistors with the rate discharge current of 5, 10kA class for high voltage systems depend on an import from advanced countries, such as Japan or U.S.A, which have developed its in the late 1980s. So in the aspect of taking independent technique the development of ZnO varistors with the rate discharge current of 5, 10kA class for high voltage systems is important. In this research project ZnO varistor elements with diameters of 35mm and 70mm for the rate discharge current of 5, 10kA class for high voltage systems are manufactured, then various chemical composition and processing variables affected the electrical and the physical characteristics of these ZnO varistors are investigated.

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss, but it needs some cooling method because heat radiation between each winding is difficult. The life of transformer is significantly dependent on the thermal behavior in windings. Many transformer designers have calculated temperature distribution and hot spot point by FEM(finite element method) to analyze winding temperature rise. In this paper, the temperature distribution and thermal stress analysis of 100kVA pole cast resin transformer for power distribution are investigated by FEM program.

In this paper, we investigated impurities content, absorption properties, and thermal properties showing by changing the content of carbon black which is semiconductive materials for underground power transmission. Specimens were made of sheet form with the three of existing resins and the nine of specimens for measurement. Impurities content of specimens and absorption properties were measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer) and Karl Fisher. And high temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis). The dimension of measurement temperature was 0$[^{\circ}]$ to 800$[^{\circ}]$, and rising temperature was 10$[^{\circ}/min]$. Impurities content was highly measured according to increasing the content of carbon black from this experimental result also absorption amount was increased according to these properties. Specially, impurities content values of the A1 and A2 of existing resins were measured more than 4000[ppm]. Heat degradation initiation temperature from the TGA results was decreased according to increasing the content of carbon black. All over, heat stabilities were EEA>EBA>pEVA. That is, heat stabilities of EVA containing the weak VA(vinyl acetate) against heat was measured the lowest.

In this paper, we Investigated effects on impurities and water of semiconductive shield through a thermal, mechanical, and absorption experiment to estimate performance of insulating materials in power cable. Specimens had been prepared 22[kV], 154[kV] XLPE power cables and then were made of sheet form with XLPE and semiconductive shield with dimension of 0.4[mm] ~1.2[mm] of thickness from power cable. Heat capacity $({\Delta}H)$ and glass trasition temperature (Tg) of XLPE sheet were measured by DSC (Differential Scanning Calorimetry). We could know that thermal stabilities of 154[kV] are more excellent than 22[kV] from this experimental result. The strain of mechanical properties in 22[kV] and 154[kV] XLPE was 486[%], 507[%] and stress was 1.74$[kgf/mm^2]$, 1.80$[kgf/mm^2]$. The absorption contents of existing semiconductive shield were measured 710[ppm] to 1,090[ppm], and semiconductive shield of 22[kV] cable was measured 14,750[ppm] to 24,780[ppm]. We thermal and mechanical properties of 154[kV] could know more excellent than 22[kV] from this experimental result.

In this paper, we researched the dielectric properties and voltage dependence on slice XLPE sheet from 22[kV] and 154[kV] power cable. studied effect for impurities and water for semiconductive shied through a dielectric properties experiment to estimate performance of insulating material in power cable. Capacitance and $tan{\delta}$ of 22[kV], 154[kV] were 52/42 pF and $7.4{\times}10^{-4}$, $2.1510^{-4}$, respectively. In these results, the trend was increased with the increase of temperature. The $tan{\delta}$ of XLPE/semiconductive layer and XLPE/water/semiconductive layer were increased as compared with that of XLPE. dielectric properties reliability of $tan{\delta}$ was small.

In order to analyze the physical and chemical characteristics of the home production porcelain insulators by change of the alumina addition amount, 36000lbs ball socket type suspension insulators which were manufactured in 1989, 1995 and 2001 removed in transmission line and an experiment was performed. By the result, 8 wt.% alumina that influences the mechanical properties and arc resistance properties in case of insulators that were manufactured in 1989 was contained. Amount of alumina was contained most by 17 wt.% in case of insulators that were manufactured in 2001.

CS HSA, 1034A와 TMOS, MTMS 실란 간의 졸겔 반응조건이 코팅도막의 특성에 미치는 영향을 조사하기 위하여 CS 종류, CS 대비 TMOS/MTMS의 함량비, 반응시간 등을 달리하여 졸을 합성하고, 합성된 졸을 slide glass에 코팅한 후 $300^{\circ}C$에서 경화시킨 도막의 특성들을 조사하였다. CS 대비 MTMS의 함량 증가와 더불어 접촉각이 증가할 것으로 예상되지만 CS의 종류, 실란함량, 반응시간 등에 따라 증가하는 모양은 상당히 차이가 있었고 HSA CS계 보다는 1034A CS계로 제작된 도막에서 MTMS 함량과 접촉각과의 상관성이 다소 우수하였다. 표면거칠기는 HSA CS계인 경우에 반응시간과 MTMS 함량에 따라 민감하게 변했지만 1034A CS계에서는 HSA계의 졸에 비해 표면 거칠기가 향상되어 반응시간과 MTMS 함량의 조건에 영향을 받지 않고 표면조도와 균질성이 우수하였다.

산성 colloidal silica(CS) 1034A, HSA와 TMOS, MTMS 실란 간의 졸겔반응조건이 코팅도막의 특성에 미치는 영향을 조사하기 위하여 1034A CS계에 대해서는 1단계로 실란들을 첨가하고 동일한 MTMS에 대해 CS/TMOS의 함량비, 반응시간을 달리하여 졸을 합성하였다. HSA계에 대해서는 2단계로 분리하여 TMOS, MTMS 실란을 첨가하는데 실란 첨가순서와 실란 함량비, 반응시간을 달리하여 졸을 합성하였다. 합성된 졸은 slide glass에 함침 코팅한 후 $300^{\circ}C$에서 경화시킨 도막의 특성들을 조사하였다. 1034A CS계는 CS/TMOS의 비가 70/30일 때 50/50인 경우보다 반응시간에 따라서 표면조도가 우수하여 접촉각에 영향을 덜 주므로 효과적인 균일 반응상으로 진행되었다. HSA CS계는 1단계로 MTMS를 먼저 첨가하고 MTMS/TMOS 비를 25/75로 첨가하면 반응시간에 따라서 표면조도 거칠기에 크게 영향 받지 않고 접촉각을 안정화시킬 수 있다.

변압기는 권선방법에 따라 많은 특성의 변화를 나타내게 되는데 일반적인 동선의 권선법과 코일형태로 동판을 가공하여 사용하는 평면 권선방법, 그리고 고전류용 변압기에 이용되는 것으로 코어의 권선창 표면을 감싸는 형태의 관형 권선방법의 3가지의 코일 형태 또는 권선방법에 따른 변압기의 특성 변화와 컨버터에 채용되었을 때의 전력효율에 대하여 고찰하였다. 평면 코일을 이용한 변압기는 높은 코일간의 결합도로 인해 가장 낮은 누설인덕턴스와 가장 높은 성능지수 및 결합계수를 나타내었고, 관형코일을 이용한 변압기는 높은 누설특성으로 인해 가장 낮은 성능지수와 결합계수를 나타내었다. 그리고 이들을 DC-DC 컨버터에 채용하여 분석한 결과 평면변압기가 가장 높은 효율을 발휘하였다. 관형변압기는 저전력에서는 높은 누설량으로 인해 효율이 상대적으로 낮지만 출력전력이 증가할수록 상승하는 발열량에 대한 방열효과가 높아 효율의 감소폭이 작아서 고주파 또는 대전류용 변압기 응용이 기대된다.

Bias magnet에 의한 평면자심재료의 전자기적 특성 변화를 분석하기 위해 E형 코어 사이에서 영구자석의 유무 및 위치 등의 gap 형성 조건에 따른 측성변화를 관찰하였다. 영구자석과 air Gap이 평면코어에 삽입 될 경우 높은 포화 전류값을 가지는데 이는 자기저항이 자성체에 비해서 상당히 높은 에어 갭의 존재로 인해 외부 인가 전류가 증가되어도 자성체에서 생성되는 자속이 대부분 에어갭 내에서 소비되기 때문이다. 그리고 Bias magnet 역할을 하는 영구자석을 자심재료에 가하게 되면 Bias에 의한 역자장과 자성체에서 발생하는 자장이 서로 상쇄되어 포화 전류는 증가하게 된다. 또한, Bias magnet로 영구자석을 삽입하연 공진주파수는 고주파 대역으로 이동하므로 대전류 고주파 특성이 요구되는 응용장치에 적용가능하다.

We present the basic properties of a superconducting current limiting fuse (SCLF) based on YBCO/Au films. The SCLFs consists of YBCO stripes covered with Au layers for current shunt. Under the source voltage of 100 $V_{rms}$, the longer the duration time of fault current was, the shorter its discharge time was. The duration time of fault current and its discharge time were reduced by increased voltages in the range of 200 - 300 $V_{rms}$. We thought that this was because the quench propagation was limited by local melting generated with higher voltage.

The piezoelectric ceramics for AE sensor piezoelectric devices are desirable to possess higher resonance vibrations. The compositions of $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS) in this work are selected for obtaining especially large electromechanical coupling factor, high mechanical quality factor and high Curie temperature. This ceramic has higher piezoelectric activity and higher electromechanical coupling factor, but the ceramic has lower Curie temperature. The piezoelectric and dielectric characteristics of PZT-PMNS ternary system are investigated as functions of $Ti^{2+}$, $Zi^{2+}$ mol rate. As the results, MPB(morphotropic phase boundary) in this piezoelectric ceramic is x=0.522. Resonance vibrations of PZT ceramics are investigated as ball-bearing drop test. For the use of AE sensor that driving with pre-amplifier, filter circuit after packed this ceramic and an elastic body.

Suspension effect has been studied by using superconductor of BiPbSrCaCuO ceramics containing $Ag_2O$. It has been cleared that $Ag_2O$ acts as pinning center which plays an important role to the suspension effect. Magnetic repulsive force which affects a superconductor located in magnetic flux from toroidal magnet has been investigated. It has been concluded that the suspension effect arises from the interaction between the pinning effect and the diamagnetic effect.