Insulator (electricity)

About: Insulator (electricity) is a research topic. Over the lifetime, 15941 publications have been published within this topic receiving 108950 citations. The topic is also known as: electrical insulator.

Plasma Response to Arcing in Ionospheric Plasma Environment: Laboratory Experiment

Abstract: Laboratory experiments are carried out to study the response of plasma to a sudden potential change induced by arcing on a solar array in low-Earth-orbit plasma environment. A solar array is biased negatively in a plasma chamber with insulator simulating coverglass or thermal paint located remotely from the arc point. When an arc occurs, electrons are ejected from the arc point to the surrounding plasma, producing a negative sheath. Shortly after the arc onset, the influx of positive charge into the circuit causes a jump of the potential, and the positive sheath is formed near the insulator surface. If the positive sheath meets the negative sheath near the arc point while the conductivity of the arc plasma is still high, a current path is formed between the arc point and the insulator surface. The current path supplies the positive charge on the insulator surface to the arc current and feeds energy to arc plasma. Experimental results show that there is a safety distance beyond which arc plasmas cannot form the current path.

Potential distribution computation and structure optimization for composite cross-arms in 750 kV AC transmission line

Abstract: As composite cross-arm will be used in domestic 750 kV AC transmission line for the first time, careful and meticulous preparatory work is highly needed. Using a three-dimension (3-D) finite-element method (FEM) software, this paper presents computation results of the potential and electric field distribution for composite crossarms in the process of structure optimization. Several optimization programs for composite cross-arm have been studied and the final design is made to omit the suspension insulator string, to increase the length of post insulators and to configure suitable grading and shielding rings based on preliminary design. A set of grading and shielding rings configuration program has been proposed. The comparison between optimized composite cross-arms and 750 kV line composite insulators indicates that composite cross-arms have better potential distribution. The electric tests demonstrate that optimized composite cross-arms have good electrical performance and can meet operation requirements.

Water as an insulator in pulsed facilities ( Review )

Abstract: Transmission lines with distributed parameters are often used as electrical energy storage units and high-voltage (high-current) pulse shapers in electrophysical facilities. To increase the pulse power and reduce the dimensions of the equipment, deionized water, purified from mechanical impurities and gas, is used as an insulator in lines. Water has a high breakdown strength ((BS) ∼ 130 kV/cm) at pulses with a duration of ∼1 µs and electrode areas of up to tens of square meters, a large value of the relative permittivity (∼80), and a small loss tangent in the frequency range 0–1 GHz. Water also possesses a number of characteristics needed to achieve the above aims. We review here the data on the electrical properties of water and the studies of it published over the last three decades; the methods for increasing the water BS and the influence of numerous factors on the BS; the physical mechanism of water breakdown and the basic regularities of the BS in strong electric fields; the BS in the most frequently used electrode systems; formulas for calculating the water BS under different conditions and over the surfaces of solid dielectrics; the characteristics of mixtures of water and ethylene glycol or methanol; water purification systems for electrophysical facilities; the comparative parameters of coaxial energy storage units having various insulators, etc. The summary generalizes the brief and predominantly reference information on the electrical properties of water and its applications for researchers, engineers, and the users of the equipment having water insulation; it can help to solve related problems more quickly and reliably.

Electrical Breakdown in a V2O3 device at the Insulator to Metal Transition

Abstract: We have measured the electrical properties of a V2O3 thin film micro bridge at the insulator metal transition (IMT). Discontinuous jumps to lower voltages in the current voltage characteristic (IV) followed by an approximately constant voltage progression for high currents indicate an electrical breakdown of the device. In addition, the IV curve shows hysteresis and a training effect, i.e. the subsequent IV loops are different from the first IV loop after thermal cycling. Low temperature scanning electron microscopy (LTSEM) reveals that the electrical breakdown over the whole device is caused by the formation of electro-thermal domains (ETDs), i.e. the current and temperature redistribution in the device. On the contrary, at the nanoscale, the electrical breakdown causes the IMT of individual domains. In a numerical model we considered these domains as a network of resistors and we were able to reproduce the electro-thermal breakdown as well as the hysteresis and the training effect in the IVs.

Movement simulation of long electric arc along the surface of insulator string in free air

Abstract: This paper presents the study of a long electric arc in free air due to lightning stroke on the parallel gap lightning protection device (PGLPD) on high-voltage overhead transmission lines. Based on the latest electric arc model, the analysis method of the magnetic field generated by the current flowing through the PGLPD, electric arc, transmission lines, steel tower, and ground wires is developed, and the movement process of the long arc along the surface of the insulator strings is simulated. The simulation results are in agreement with the experimental results. The study is very helpful for the optimal design and suitable assemblage of the PGLPD