Transient Voltage UWB Online Monitoring System for Insulation Failure Analysis and Fault Location of GIL

Transient voltage generated in ultra-high voltage (UHV) transmission system has a severe impact on the insulation state of gas-insulated transmission lines (GIL). In order to monitor the transient voltage process occurring in UHV GIL during operation, this paper constructs a transient voltage ultra-wideband (UWB) online monitoring system based on capacitive voltage division. This system has been applied in an 1100 kilovolt (kV) GIL utility tunnel project. It can be used to analyze the characteristics of the recorded transient voltage waveforms for distinguishing different types of insulation failure. In this paper, through the case studies in time domain and time–frequency domain, the case of SF6 gap breakdown and that of post insulator flashover have differentiated characteristics in instantaneous frequency. Additionally, a case of secondary discharge is successfully estimated through the time–frequency distribution of the transient voltage. In order to find the malfunctioning chamber of GIL rapidly, a two-terminal TW-based fault location method based on this monitoring system is developed in this paper. The case study validates the locating accuracy which directly support for shortening the maintenance time of GIL.

Small Size Digital Oscilloscope Using ARM Processor

Oscilloscopes are indispensable tools for anyone designing, manufacturing or repairing electronic equipment. In today’s fast-paced world, engineers need the best tools available to solve their measurement challenges quickly and accurately. As the eyes of the engineer, oscilloscopes are the key to meeting today’s demanding measurement challenges. There are many types of oscilloscope available in the market. The main types of oscilloscopes are analog oscilloscope, digital oscilloscope and PC based oscilloscope. From which the digital oscilloscope are widely used now a days due there accuracy portability, high speed, high resolution, data storing capability etc. here we provide an alternative solution which is basically a digital oscilloscope with almost all the control options which any standard digital oscilloscope has. This paper describes the development of a portable, very low cost oscilloscope. The user can start/stop the display, adjust the time division and adjust the voltage division. The features of this device make it suitable for implementing as an educational re-source for graduate students from Electrical, Electronics, Instrumentation, and Computer Science faculties.

GSM Based Underground Cable Open and Short Circuit Fault Detection

The underground cable system is a common practice followed in many urban areas. While a fault occurs for some reason, at that time the repairing process related to that particular cable is difficult due to not knowing the exact location of the cable fault. Hence, the main objective of this project is to determine the distance of underground cable fault from base station in kilometers using an Arduino board and GSM. The project uses the standard concept of Ohms law and voltage division rule to detect and locate the fault. The fault occurring at a particular distance and the respective phase is displayed on a LCD interfaced to the Arduino board and information regarding fault occurrence is sent to control areas using GSM modules.

Anomalous low impedance for small platinum microelectrodes

Electrical measurement of the activity of individual neurons is a primary goal for many invasive neural electrodes. Making these “single unit” measurements requires that we fabricate electrodes small enough so that only a few neurons contribute to the signal, but not so small that the impedance of the electrode creates overwhelming noise or signal attenuation. Thus, neural electrode design often must strike a balance between electrode size and electrode impedance, where the impedance is often assumed to scale linearly with electrode area. Here we test this assumption by measuring the impedance at 1 kHz for differently sized electrodes. Surprisingly, we find that for Pt electrodes (but not Au electrodes) this assumption breaks down for electrodes with diameters of less than 10 microns. For these small sizes, Pt electrodes have impedance values that are up to 3-fold lower than expected. By investigating the impedance spectrum of Pt and Au electrodes we find a transition between planar and spherical diffusion for small electrodes combined with the pseudo-capacitance of proton adsorption at the Pt surface can explain this anomalous low impedance. These results provide important intuition for designing small, single unit recording electrodes. Specifically, for materials that have a pseudo-capacitance or when diffusional capacitance dominates the total impedance, we should expect small electrodes will have lower-than-expected impedance values allowing us to scale these devices down further than previously thought before thermal noise or voltage division limits the ability to acquire high-quality single-unit recordings.

Highly efficient ultra-flexible tandem organic light-emitting diodes adopting a non-doped charge generation unit

Due to the voltage division of charge generation unit (CGU), the power efficiency of tandem organic light-emitting diodes (TOLEDs) is usually lower than that of the single-unit devices, which severely...

Simulation and Experimental Research on Overvoltage Measurement of Hybrid CVT

The CVT equipment running on site is slightly modified to form a hybrid CVT to achieve transient overvoltage measurement, which is theoretically feasible and practical. In order to study the voltage division method based on the hybrid CVT to measure the overvoltage of the power system, that is, the low voltage capacitor C3 is connected in series between the low voltage terminal of the medium voltage capacitor C2 of the traditional CVT and the ground, and the transient overvoltage measurement is realized through C3. This article uses ATP-EMTP to establish its high-frequency transient model for simulation analysis. For further verification, a power frequency voltage test and an impulse voltage test were carried out on the 110kV hybrid CVT produced by Taikai Transformer Factory, focusing on the analysis of the partial voltage characteristics of the capacitor C3. The simulation results show that the C3 partial pressure method can achieve a relatively accurate measurement of the transient overvoltage. The test results show that the voltage across C3 is affected by uncertain factors and has an impact phenomenon. The above analysis process and results have certain practical value for designing actual products.