A Dual-Slot Barrier Sensor for Partial Discharge Detection in Gas-Insulated Equipment

This paper reports on the development and testing of a novel barrier sensor for UHF Partial Discharge (PD) detection in gas-insulated equipment. The sensor features a unique dual-slot planar antenna backed by an air-filled cavity. The dual-slot arrangement allows different parts of the antenna to resonate at different frequency ranges in the UHF spectrum. As a result, the sensor exhibits broader bandwidth and higher sensitivity than other barrier sensors. Finite Element Analysis simulations have been used to optimize the sensor design. Furthermore, testing using a specially made PD test rig, GTEM cell testing and testing on a gas-insulated line section in the high voltage laboratory, have validated the simulation results and the capabilities of the sensor. The Dual-Slot Barrier (DSB) sensor exhibits a bandwidth of 0.3 -2.0 GHz with a mean effective height of 13 mm, and an effective height above 2 mm for 90% of the frequency range. The sensor can be used with both wideband instruments, such as oscilloscopes, and narrow band instruments such as frequency downconverters. Additionally, its optimized dimensions and unique replaceable sealing attachment ensure maximum compatibility for retrofitting on a wide range of equipment

Laboratory and field partial discharge measurement in HVDC power cables

A range of experimental and field measurements of partial discharge (PD) activity under high voltage direct current (HVDC) conditions have been conducted with the goal of developing effective monitoring techniques for PD in HVDC cables and ancillary equipment, particularly in offshore renewable energy HVDC grid installations. Laboratory measurements on insulation test objects and cross linked polyethylene (XLPE) cable samples have been conducted to better understand the characteristics of PD activity under direct current (DC) stress in comparison with AC. In addition, long-term PD measurements carried out at both an HVDC cable aging laboratory and an in-service HVDC interconnector circuit are presented together with a description of the monitoring system architecture

Effect of mass fish mortality on zooplancton structure and dynamics in a small Italian lake (Lago di Annone)

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Optimization of a High Frequency Current Transformer sensor for Partial Discharge Detection using Finite Element Analysis

High-frequency current transformer (HFCT) sensors are widely used for partial discharge detection due to their versatility, high sensitivity, and wide bandwidth. This paper reports on a finite-element analysis (FEA) methodology that can be employed to optimize HFCT performance. The FEA model consists of accurate 3D representations of the sensor components. Two different FEA software modules were used in order to cover the wide operating frequency range of the sensor. The simulation computes the frequency response of the sensor in the range 0.3-50 MHz for various HFCT geometric and material parameters, specifically the number of winding turns, spacer thickness, aperture size, and core material. A prototype HFCT was constructed and the measured response compared with that of the simulation. The shapes of the responses were similar, with the simulated sensitivity being higher than the measured sensitivity by 1 dB on average. The measured low-frequency cutoff of the sensor was found to be only 0.05 MHz lower than that of the simulation

A Wideband Spiral UHF Coupler with Tuning Nodules for Partial Discharge Detection

This paper reports on the development and testing of a wideband spiral-shaped coupler for a partial discharge (PD) detection in the UHF spectrum. The coupler design, which is based on the log-periodic spiral slot antenna, has been optimized using finite element simulation. The following parameters have been optimized: feed location, arm termination shape, width of arm root, and termination. The unique feature of the coupler is the inclusion of tuning nodules on the spiral arms, which widen its bandwidth without the need for additional components. Tests in an anechoic chamber have shown a close agreement with the simulation results. The coupler exhibits a wide bandwidth (S11 <; -9.55 dB) between 0.5-2.6 GHz and a peak gain of 4.8 dBi (at 1.35 GHz), while using an infinite balun coaxial feed, which allows for an input impedance of 50 Ω. The PD testing in the laboratory has shown that the phase resolved PD patterns acquired with the coupler are very similar to those captured with conventional PD sensors. An application of the coupler as an internal sensor in a gas-insulated busduct is detailed and a bandwidth comparison with other UHD PD sensors is provided