Influence of the Semiconductive Composites Doped with Li4Ti5O12 on Space Charge Implantation in LDPE

2021 ◽  
Author(s):  
Hongxia Yin ◽  
Shiyi Zhao ◽  
Chuncheng Hao ◽  
Qingquan Lei
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
High Voltage ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Conductive Network ◽  
Charge Accumulation ◽  
Insulation Layer ◽  
Injection Process ◽  
Key Factor

Abstract Space charge accumulation in the insulating layers of high-voltage directed current (HVDC) cables is the key factor that leads to their degradation and limits the operation safety. Hence, it is necessary to effectively inhibit carrier implantation to these layers. In this study, a new method is proposed to suppress the charge implantation to the cable insulation layer, a certain amount of Li4Ti5O12 nanopowder is doped in the semiconductive screen to enhance the internal conductive network and homogenize the electric field. The influences of Li4Ti5O12 particles in the semiconductive composite screen on the positive temperature coefficient effect and space charge injection process are explored. The obtained results reveal that the charge quantity in the insulation layer corresponding to the minimum peak resistivity is reduced by 49.7%, 58.9%, and 46.9% after the polarization at a Li4Ti5O12 content of 4 wt.% and electric field strengths of 10, 20, and 30 kV/mm, respectively.

scholarly journals Effect of Ionic Conductors on the Suppression of PTC and Carrier Emission of Semiconductive Composites

2020 ◽  
Vol 10 (8) ◽  
pp. 2915 ◽  
Author(s):  
Yingchao Cui ◽  
Hongxia Yin ◽  
Zhaoliang Xing ◽  
Xiangjin Guo ◽  
Shiyi Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Space Charge ◽  
Current Method ◽  
Positive Temperature Coefficient ◽  
Ionic Conductor ◽  
Positive Temperature ◽  
Ionic Conductors ◽  
Ptc Effect ◽  
High Voltage Direct Current ◽  
Key Factor

The positive temperature coefficient (PTC) effect of the semiconductive layers of high-voltage direct current (HVDC) cables is a key factor limiting its usage when the temperature exceeds 70 °C. The conductivity of the ionic conductor increases with the increase in temperature. Based on the characteristics of the ionic conductor, the PTC effect of the composite can be weakened by doping the ionic conductor into the semiconductive materials. Thus, in this paper, the PCT effects of electrical resistivity in perovskite La0.6Sr0.4CoO3 (LSC) particle-dispersed semiconductive composites are discussed based on experimental results from scanning electron microscopy (SEM), transmission electron microscopy (TEM) and a semiconductive resistance test device. Semiconductive composites with different LSC contents of 0.5 wt%, 1 wt%, 3 wt%, and 5 wt% were prepared by hot pressing crosslinking. The results show that the PTC effect is weakened due to the addition of LSC. At the same time, the injection of space charge in the insulating sample is characterized by the pulsed electroacoustic method (PEA) and the thermally stimulated current method (TSC), and the results show that when the content of LSC is 1 wt%, the injection of space charge in the insulating layer can be significantly reduced.

Inhibiting Effect of Nonlinear Shielding Layer on Electrical Tree Propagation inside Insulation Layer of High-Voltage Cable

2014 ◽  
Vol 989-994 ◽  
pp. 1273-1277
Author(s):  
Chang Ming Li ◽  
Bao Zhong Han ◽  
Long Zhao ◽  
Chun Peng Yin
Keyword(s):  
Electric Field ◽  
Field Distribution ◽  
High Voltage ◽  
Electric Field Distribution ◽  
Uniform Electric Field ◽  
Insulation Layer ◽  
Breakdown Time ◽  
Electrical Tree ◽  
Traditional Structure ◽  
Initiation And Propagation

Nonlinear insulated materials can uniform electric field distribution in non-uniform electric field. In order to inhibit the electric tree initiation and propagation inside high-voltage cross-linked polyethylene (XLPE) insulated cable, a kind of 220kV high-voltage XLPE insulated cable with new structure is designed by embedding nonlinear shielding layer into XLPE insulation layer of high-voltage cable with traditional structure in this study. Experimental and simulation results indicate that the nonlinear shielding layer can effectively inhibit electrical tree propagation inside the XLPE specimens, and obviously extend the breakdown time caused by electric tree propagation. When the electrical tree propagates into the nonlinear shielding layer sandwiched between insulation layers of cable, the electric field distribution near the tip of electrical tree is obviously improved. These findings prove the feasibility and the effectivity of inhibiting electrical tree propagation inside high-voltage cable by adding nonlinear shielding layer into the insulation layer.

A comparison of injection laws for the space charge equations in gases and dielectrics

1993 ◽  
Vol 443 (1919) ◽  
pp. 517-546 ◽  
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Field Distribution ◽  
Steady Motion ◽  
Plane Geometry ◽  
Symmetric Problem ◽  
Injection Process ◽  
Underlying Geometry ◽  
Current Characteristics ◽  
The Stability

We consider the steady motion of space charge from an injecting electrode to an earthed electrode in both a gas and a dielectric. Three models governing the process of charge injection from the electrode into the medium are compared and the resulting voltage–current characteristics calculated. In particular we examine injection laws in which the electric field, charge or current are specified. It is shown that if the injecting electrode is small in comparison to the underlying geometry then the resulting field distribution is almost independent of the injection process. The stability of the three models is compared and it is shown that the field specified and charge specified models are always stable. The calculations are performed exactly for the case of a symmetric problem and make use of the Deutsch approximation for a needle-plane geometry.

scholarly journals Electrochromism of Viologen/Polymer Composite: From Gel to Insulating Bulk for High-Voltage Applications

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5901
Author(s):  
Yongjie Nie ◽  
Meng Zhang ◽  
Yuanwei Zhu ◽  
Yu Jing ◽  
Wenli Shi ◽  
...  
Keyword(s):  
Power Systems ◽  
Space Charge ◽  
Electric Fields ◽  
High Voltage ◽  
Vinylidene Fluoride ◽  
Power Equipment ◽  
Charge Accumulation ◽  
Charge Detection ◽  
Continuous Current ◽  
High Electric Fields

Power equipment operates under high voltages, inducing space charge accumulation on the surface of key insulating structures, which increases the risk of discharge/breakdown and the possibility of maintenance workers experiencing electric shock accidents. Hence, a visualized non-equipment space charge detection method is of great demand in the power industry. Typical electrochromic phenomenon is based on redox of the material, triggered by a voltage smaller than 5 V with a continuous current in μA~mA level, which is not applicable to high electric fields above 106 V/m with pA~nA operation current in power equipment. Until now, no naked-eye observation technique has been realized for space charge detection to ensure the operation of power systems as well as the safety of maintenance workers. In this work, a viologen/poly(vinylidene fluoride-co-hexafluoropropylene)(P(VDF–HFP)) composite is investigated from gel to insulating bulk configurations to achieve high-voltage electrical-insulating electrochromism. The results show that viologen/P(VDF–HFP) composite bulk can withstand high electric fields at the 107 V/m level, and its electrochromism is triggered by space charges. This electrochromism phenomenon can be visually extended by increasing viologen content towards 5 wt.% and shows a positive response to voltage amplitude and application duration. As viologen/P(VDF–HFP) composite bulk exhibits a typical electrical insulating performance, it could be attached to the surface of insulating structures or clamped between metal and insulating materials as a space charge accumulation indicator in high-voltage power equipment.

The Simulation of Electret Effect in Zn0.7Cd0.3S Layers

2005 ◽  
Vol 10 (1) ◽  
pp. 77-82
Author(s):  
F. Kuliešius ◽  
S. Tamošiūnas ◽  
A. Žindulis
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Charge Accumulation ◽  
Contact Mode ◽  
Charge Formation ◽  
Electret Effect

The regularities of the dark discharge in ionic contact mode as well as of the thermoelectret effect have been investigated for Zn0.7Cd0.3S layers. The peculiarities of electret charge formation as well as the electret voltage dependences on poling electric field, polarisation time and temperature have been analysed in Zn0.7Cd0.3S layers during the present work. The model of space charge accumulation have been proposed.

Experimental Verification of a Self-Triggered Solid-State Circuit Breaker Based on a SiC BIFET

2017 ◽  
Vol 897 ◽  
pp. 665-668
Author(s):  
Matthaeus Albrecht ◽  
Andreas Huerner ◽  
Tobias Erlbacher ◽  
Anton J. Bauer ◽  
Lothar Frey
Keyword(s):  
Solid State ◽  
Temperature Coefficient ◽  
High Voltage ◽  
Circuit Breaker ◽  
Negative Temperature ◽  
Positive Temperature Coefficient ◽  
Positive Temperature ◽  
Solid State Circuit ◽  
Current Voltage ◽  
Solid State Circuit Breaker

In this work, the feasibility of the Bipolar-Injection Field Effect-Transistor (BIFET) [5] in two different Dual Thyristor type circuits [4] for an application as solid-state circuit breaker (SSCB) is experimentally verified. The Dual Thyristor type circuits are assembled from discrete silicon JFETs and a silicon carbide BIFET and are electrically characterized at various temperatures. The current-voltage characteristic shows the expected regenerative self-triggered turn-off capability under over-currents and the option to control the turn-off current by a passive resistor network. The issue with the adverse positive temperature coefficient of the trigger-current can be solved by putting the SiC BIFET in a cascode arrangement with a silicon Dual Thyristor. In this configuration the SiC BIFET provides the high voltage blocking capability and the silicon Dual Thyristor with its negative temperature coefficient controls the trigger-current. Transient analyses of both circuits indicate fast switching times of less than 50 μs seconds. It is demonstrated for the first time, that the SiC BIFET, due to its normally-on behaviour, used in a Dual Thyristor type circuit is a promising concept for self-triggered fuses in high current and high voltage applications.

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