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ZnO-based varistors have been widely applied in surge protection devices because of their excellent nonlinear current-voltage (I-V) characteristic and energy absorption ability. Manganese is always added into ZnO-based varistors in order to enhance the nonlinear characteristic of materials. In the present work, the dielectric properties of Mn-doped ZnO-Bi2O3 varistors at extremely low temperatures...
Algae was widely observed on composite insulators in hot and humid climate, which affected external insulation performance of polymeric insulating materials especially on hydrophobic properties. To fully understand the hydrophobic behavior of algae-fouled insulators, this paper simulated algae growing process on silicon rubbers (SIRs) surface under artificial laboratory conditions. Hydrophobicity...
Gas Insulted Switcher (GIS) is one of the most important equipments in power system. Partial discharges (PDs) detection has the vital significance to the condition diagnosis of GIS. In this paper, a multispectral optical PD detection system based on three photomultipliers (PMs) with corresponding light filters in the front is built to detect PD under power frequency voltage. The variations of the...
Gas Insulated Switchgear has been widely used because of its high reliability. But in the long run discharge faults and mechanical faults often happen to GIS, early GIS fault detection are mainly for GIS partial discharge fault detection, but this paper focuses on the study of mechanical vibration fault. Based on acoustic signal, the paper introduces the common mechanical fault types and fault mechanism;...
The core is the key component in the transformer. The core loosening is one of common faults of the transformer, which will cause the noise and vibration obviously increasing then lead to facility damages. The feature extraction method for the transformer core loosening based on variational mode decomposition is proposed in this paper to analyze the core loosening vibration signal which has non-stationary...
Insulator string is an important part of UHV AC transmission line, and plays an important role in electrical insulation and mechanical support. The new type of insulator string can realize optimization of wire suspension modes and insulator string performance by changing the string structure, which is of great practical value for special transmission corridors with excessively high costs of cleaning...
Thermal degradation due to dry band arcing in the discharge region causes tracking and erosion failure of composite insulators. This work investigates resistance against tracking and erosion of silicone rubber filled with micron sized aluminum nitride (AlN) and boron nitride (BN) particles. Their performances are evaluated by comparing the average tracking length, eroded mass and thermal distribution...
Very fast transient overvoltage (VFTO) caused mainly during switching operations of the disconnectors has been a serious threat to gas-insulated switchgear (GIS). The paper presented a new approach to suppress the VFTO by great nano-crystalline rings and small ferrite rings. In this research, the test platform consisted of a steep fronted impulse device and a real 550 kV GIS. Then, series of comparative...
GIS (Gas Insulated Switchgear) is extensively used in the power grid to switch lines and protect the system. The higher requirements are proposed due to the increasing voltage level when comes to its internal over-heating problems. In this paper, the temperature rise of 40.5kV high voltage switchgear is researched with the help of ANSYS APDL and CFX. Firstly, the electromagnetic loss and generated...
To satisfy the rapid development of energy requirements, power transmission with higher voltage must be adopted. The large improvement in transmission voltage needs more excellent power equipment and better materials to meet its insulation requirement. Polytetrafluoroethylene (PTFE) nozzle used in high voltage circuit breaker faces the issue of breakdown and arc ablation, and thus superior performance...
With the feed-in of electricity proportion rising, Shanghai grid become a typical large city Receiving-end grid. Voltage stability make great influence to power grid operating safely and stably. Firstly, brief introduction of Shanghai power grid current situation. Secondly, analyze summer and winter voltage stability of Shanghai power grid in different operation modes, including normal operation and...
The air-polyimide surface insulating system is regard as the weak point in high frequency power transformer, since the surface breakdown strength of the dielectric is much lower than its bulk breakdown strength. However, it still remains unclear regarding the deterioration mechanism of air-polyimide surface insulating system under high frequency sinusoidal voltage. In this paper, surface discharge...
Electrical properties of insulating materials is the key to new large capacity pipeline transmission technology. The dielectric loss factor, capacitance, lightning withstand voltage, local discharge, power frequency breakdown strength of the new polymer cement concrete (PCC) were studied. Through the experimental analysis: With the increase of temperature, The relative dielectric constant of PCC sample...
Ever since Chinese electric power reform in 2002, different live test approaches were introduced and applied in relative industries. There were at least 26 live test approaches applied in the field of power transformation, power transmission and power distribution. The essay introduced a comprehensive dynamic and flexible effectivity evaluation system, which helped to evaluate the strengths and weaknesses...
High energy consumption limits low — temperature plasma application in terms of waste gas treatment. In order to further improve the efficiency of handling waste gas by using gliding arc plasma, it is put forward that gliding arc plasma is cooperated with photocatalyst to deal with exhaust gas. In this paper, sulfur dioxide was acted as target gas to be dealt with. The molecular sieve loading TiO2...
Power transformer is one of the most expensive equipment and plays a vital role in power transmission and distribution (T&D) systems. This paper presents a comprehensive risk assessment method of transformers, which integrates the operating condition of transformer and the consequences of transformer failure. Health index provides a practical tool for evaluating the state of transformers. Meanwhile,...
The statistical characteristics of the impulse breakdown time lag in transformer oil are studied over a wide range of pulse width, and the statistical discharge time lag and the discharge formation time lag are calculated by the Laue's pattern. Then a physical model for the discharge initiation process in quasi-uniform field is built. It is supposed that the field emission current generated by the...
With the progress of modern science and technology, the impact of electromagnetic radiation on biological health condition is increasing. The influence and the mechanism of interactions between electromagnetic radiation and biological tissues are urgently to be studied. In this paper, the variation of dielectric properties of 4 typical SD rat tissues (muscle, liver, kidney, heart) with irradiation...
Whether the surface resistance to erosion of a polymer nanocomposite system containing a conductive phase could be affected is the topic of this contribution. In order to answer this question, two material systems were fabricated and studied. Low-density polyethylene (LDPE) was prepared using ball-milling with Graphene Oxide (GO) up to 0.3 wt%. Epoxy resin was mixed with Carbon Black (CB) up to a...
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