scholarly journals Study on High Frequency Surface Discharge Characteristics of SiO2 Modified Polyimide Film

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4387
Author(s):  
Zhaoliang Xing ◽  
Wenhan Chen ◽  
Zhihui Li ◽  
Naifan Xue ◽  
Fei Li ◽  
...  
Keyword(s):  
High Frequency ◽  
Life Time ◽  
Polyimide Film ◽  
Surface Discharge ◽  
Discharge Process ◽  
Half Cycle ◽  
Electrical Stress ◽  
Number Of Discharges ◽  
Late Stages ◽  
Positive Half

Polyimide (PI) can be used as a cladding insulation for high frequency power transformers, and along-side discharge can lead to insulation failure, so material modification techniques are used. In this paper, different doped nano-SiO2 are introduced into polyimide for nanocomposite modification. The results of testing the life time of high-frequency electrical stress along-side discharge show that the 10% SiO2 doping has the longest life time. The results show that: for composites prone to corona, their flashover causes more damage, and both positive half-cycle and polarity reversal discharges are more violent; compared to pure PI, the positive half-cycle and overall discharge amplitude and number of modified films are smaller, but the negative half-cycle is larger; at creeping development stages, the number of discharges is smaller, and the discharge amplitude of both films fluctuates in the mid-term, with the modified films having fewer discharges and the PI films discharging more violently in the later stages. The increase in the intensity of the discharge was greater in the later stages, and the amplitude and number of discharges were much higher than those of the modified film, which led to a rapid breakdown of the pure polyimide film. Further research found that resistivity plays an important role in the structural properties of the material in the middle and late stages, light energy absorption in the modified film plays an important role, the distribution of traps also affects the discharge process, and in the late stages of the discharge, the heating of the material itself has a greater impact on the breakdown, so the pure polyimide film as a whole discharges more severely and has the shortest life.

Study on the high frequency insulation strength of disiloxane modified polyimide film

2020 ◽  
Author(s):  
Chong Zhang ◽  
Zhaoliang Xing ◽  
Pengfei Wu ◽  
Xiying Dai ◽  
Zhiyun Han ◽  
...  
Keyword(s):  
High Frequency ◽  
Polyimide Film

Horizontal Vestibuloocular Reflex Evoked by High-Acceleration Rotations in the Squirrel Monkey. II. Responses After Canal Plugging

1999 ◽  
Vol 82 (3) ◽  
pp. 1271-1285 ◽  
Author(s):  
David M. Lasker ◽  
Douglas D. Backous ◽  
Anna Lysakowski ◽  
Griffin L. Davis ◽  
Lloyd B. Minor
Keyword(s):  
High Frequency ◽  
Peak Velocity ◽  
Vestibular Function ◽  
Semicircular Canals ◽  
Vestibuloocular Reflex ◽  
Half Cycle ◽  
High Acceleration ◽  
Linear And Nonlinear ◽  
Residual Response ◽  
Sinusoidal Rotations

The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in four squirrel monkeys after unilateral plugging of the three semicircular canals. During the period (1–4 days) that animals were kept in darkness after plugging, the gain during steps of acceleration (3,000°/s2, peak velocity = 150°/s) was 0.61 ± 0.14 (mean ± SD) for contralesional rotations and 0.33 ± 0.03 for ipsilesional rotations. Within 18–24 h after animals were returned to light, the VOR gain for contralesional rotations increased to 0.88 ± 0.05, whereas there was only a slight increase in the gain for ipsilesional rotations to 0.37 ± 0.07. A symmetrical increase in the gain measured at the plateau of head velocity was noted after animals were returned to light. The latency of the VOR was 8.2 ± 0.4 ms for ipsilesional and 7.1 ± 0.3 ms for contralesional rotations. The VOR evoked by sinusoidal rotations of 0.5–15 Hz, ±20°/s had no significant half-cycle asymmetries. The recovery of gain for these responses after plugging was greater at lower than at higher frequencies. Responses to rotations at higher velocities for frequencies ≥4 Hz showed an increase in contralesional half-cycle gain, whereas ipsilesional half-cycle gain was unchanged. A residual response that appeared to be canal and not otolith mediated was noted after plugging of all six semicircular canals. This response increased with frequency to reach a gain of 0.23 ± 0.03 at 15 Hz, resembling that predicted based on a reduction of the dominant time constant of the canal to 32 ms after plugging. A model incorporating linear and nonlinear pathways was used to simulate the data. The coefficients of this model were determined from data in animals with intact vestibular function. Selective increases in the gain for the linear and nonlinear pathways predicted the changes in recovery observed after canal plugging. An increase in gain of the linear pathway accounted for the recovery in VOR gain for both responses at the velocity plateau of the steps of acceleration and for the sinusoidal rotations at lower peak velocities. The increase in gain for contralesional responses to steps of acceleration and sinusoidal rotations at higher frequencies and velocities was due to an increase in the gain of the nonlinear pathway. This pathway was driven into inhibitory cutoff at low velocities and therefore made no contribution for rotations toward the ipsilesional side.

scholarly journals KARAKTERISTIK SURFACE PARTIAL DISCHARGE DI SEKITAR ANTARMUKA PCB PADA PELAT-PELAT ELEKRODA PADA ISOLASI UDARA DAN MINYAK

2020 ◽  
Vol 6 (2) ◽  
pp. 65-73 ◽  
Author(s):  
Neris Peri Ardiansyah ◽  
Resa Pramudita
Keyword(s):  
High Frequency ◽  
Partial Discharge ◽  
Current Transformer ◽  
Surface Discharge ◽  
High Frequency Current ◽  
Inception Voltage ◽  
Frequency Current

Penggunaan peralatan tegangan tinggi pada konverter elektronik daya atau modul daya memiliki pengaruh terhadap sistem isolasi peralatan yang digunakan. Efek yang dihasilkan adalah pelepasan sebagian atau partial discharge (PD), dimana hal tersebut depengaruhi oleh bentuk tegangan, yang mana fenomena PD ini adalah awal mula terjadinya kegagalan dalam suatu peralatan. Pada penelitian ini dilakukan Pengukuran PD dengan mengacu pada Standar IEC 60270 yang menggunakan metode elektrik sebagai pengukuran yang digunakan untuk pengujian PD pada bahan PCB dengan alat ukur yang digunakan adalah RC detektor dan High Frequency Current Transformer (HFCT). Pengukuran PD dilakukan dengan membuat model elektroda yang digunakan pada pengujian untuk membuat sumber PD. Elektroda yang digunakan adalah model elektroda Homogen pelat-pelat. Pengujian pada PCB dilakukan untuk mengetahui karakteristik surface discharge pada disekitar antarmuka pelat-pelat elektroda. Parameter yang digunakan dalam pengukuran yaitu Partial Discharge Inception Voltage (PDIV), Partial Discharge Extinction Voltage (PDEV), Bentuk Gelombang PD, dan Pola Phasa PD.

Low-frequency Data Acquisition from High-frequency Source Using Half-cycle Pseudorandom Sweep

2016 ◽  
Author(s):  
Y. Nakamura ◽  
M. Takanashi ◽  
M. Nakatsukasa ◽  
Y. Kunishi ◽  
J. Sakakibara ◽  
...  
Keyword(s):  
Data Acquisition ◽  
High Frequency ◽  
Low Frequency ◽  
Half Cycle ◽  
Frequency Data ◽  
Frequency Source

Study on the Insulating Spacers Surface Discharge of GIS

2013 ◽  
Vol 385-386 ◽  
pp. 1209-1212
Author(s):  
Yun Peng Liu ◽  
Zi Jian Wang ◽  
Yan Song Li
Keyword(s):  
Photon Number ◽  
Current Method ◽  
Rapid Expansion ◽  
Particle Collision ◽  
Surface Discharge ◽  
Discharge Process ◽  
Testing Technology ◽  
Important Position ◽  
Ultraviolet Photons

Gas insulated switchgears occupy an important position in the power system.Insulating spacers are important parts in GIS, a research on the surface discharge characteristics is conducted, mainly using ultraviolet imaging technology, ultrasonic testing technology and pulse current method to test the whole discharge process. Based on the data analysis, get the following conclusion: 1) Ultraviolet photons indicator shows the "saturation" characteristic, when the voltage up to 68kV later, continue to increase the voltage, ultraviolet photon number increase is not obvious; 2) In the basin insulator defect, with discharge intensifies, charged particle collision more intense, the heat increase, so the local volume rapid expansion, the pressure increase lead to enhance the ultrasonic signal. These works provide a valuable reference for follow-up study of GIS.

Portable Acoustic-Electric Combined System for Partial Discharge Detection in GIS

2013 ◽  
Vol 303-306 ◽  
pp. 555-561
Author(s):  
Bin Liu ◽  
Yue Hu ◽  
Qian Chen ◽  
Wei Dong Zhang ◽  
Ling Yu Cao ◽  
...  
Keyword(s):  
High Frequency ◽  
Phase Distribution ◽  
Detection System ◽  
Partial Discharge ◽  
Time Difference ◽  
Discharge Process ◽  
Distribution Analysis ◽  
Ultra High Frequency ◽  
Time Frequency ◽  
Discharge Detection

A portable acoustic-electric detection system for GIS partial discharge is developed. This system integrates both high and low-speed data acquisition devices, and is capable of multichannel joint detection of ultra-high-frequency and high-frequency current as well as ultrasonic signal generated during the GIS partial discharge process. The software of this system is developed based on LabVIEW. It can successively capture, acquire and store the pulse waveform of partial discharge, calculate the phase of discharge pulse and realize time-frequency analysis and amplitude-phase distribution analysis of PD signals at the same time. By calculating the time difference of multi-channel ultra-high-frequency (UHF) signals and of PD ultrasonic signals or the time difference between the two, the system is able to locate the PD source. This system has been applied to on-site partial discharge detection of 220kV and 500kV GIS substations, and the test results have verified the performance of the system.

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