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.

Aging evaluation of silicone rubber insulators using leakage current and flashover voltage analysis

Abstract: Ultraviolet (UV) radiation decreases the hydrophobicity of silicone rubber (SiR) insulators. Lack of hydrophobicity on the surface of such insulators lowers the flashover voltage and increases the Leakage Current (LC) of insulators in the moist environment. This paper presents the artificial UV radiation effects on three types of 20 kV SiR insulators in a chamber with nine UV-C lamps (50 W/m2) for up to 5000 hours. To simulate the moist environment, solid layer method is applied according to IEC 60507 that includes artificial pollution deposition on the insulator surface. Fast Fourier transform of the LC waveforms indicates that the third and the fifth harmonic components are quite sensitive to any incremental discharge on the insulator surface. This sensitivity makes the frequency spectrum of the LC a good criterion to distinguish three distinct SiR insulator situations under the electric stress: 1) no discharge, 2) dry band arcing/corona discharge and 3) continuous arc. Thermogravimetric analysis (TGA) and scanning electron microscope images depict that the polluted insulators include much larger degraded parts under electric stress after aging. Measurements also show that the flashover voltages and the hydrophobicity of aged insulators decrease as the UV exposure time increases for different levels of moisture and pollution.

Study on AC Flashover Performance and Discharge Process of Polluted and Iced IEC Standard Suspension Insulator String

Abstract: Based on the results of experimental investigations performed on the polluted and iced IEC standard suspension insulator strings of 3~21 units, the ac flashover performance and discharge process are discussed in this paper. It is put forward that the icing stress product (ISP), defined as the product of the ice-layer conductivity and the ice layer weight per centimeter of dry arc distance can be taken as a characteristic parameter to indicate the effect of ice accretions and contaminants on the flashover voltage. The flashover stress of an ice-covered insulator string can be expressed as a power function of ISP and has a linear relationship with the length of the insulator string. The partial arc of an iced insulator string is initiated by the breakdown of the air gaps between the tips of icicles and iced insulator surface and the persistence is much longer than that of a polluted insulator string

Organic Thin-Film Transistors on a Plastic Substrate with Anodically Oxidized High-Dielectric-Constant Insulators

Abstract: Organic thin-film transistors (OTFTs) which use Ta2O5 as the gate insulators were fabricated on plastic substrates. The gate insulators were synthesized by anodizing the gate electrodes fabricated as stacked structures of aluminum (Al) and tantalum (Ta) at room temperature. The stacked structure suppressed the stress at the interface between the substrate and metal electrodes so that cracks on Ta could be avoided. The organic semiconductor pentacene was used as the active layer on the gate insulator. The OTFTs showed the best performance at an operating voltage of 5 V and a good field-effect mobility of 0.36 cm2/Vs on plastic substrates. The structural order of the pentacene in the film and the temperature dependence of the leakage current in the insulator were also studied to improve the device characteristics.

Metal-to-insulator switching in quantum anomalous Hall states

Abstract: After decades of searching for the dissipationless transport in the absence of any external magnetic field, quantum anomalous Hall effect (QAHE) was recently achieved in magnetic topological insulator films. However, the universal phase diagram of QAHE and its relation with quantum Hall effect (QHE) remain to be investigated. Here, we report the experimental observation of the giant longitudinal resistance peak and zero Hall conductance plateau at the coercive field in the six quintuple-layer (Cr0.12Bi0.26Sb0.62)2Te3 film, and demonstrate the metal-to-insulator switching between two opposite QAHE plateau states up to 0.3 K. Moreover, the universal QAHE phase diagram is confirmed through the angle-dependent measurements. Our results address that the quantum phase transitions in both QAHE and QHE regimes are in the same universality class, yet the microscopic details are different. In addition, the realization of the QAHE insulating state unveils new ways to explore quantum phase-related physics and applications.