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Four Cases of non-uniform Electrical FieldsFour Cases of non-uniform Electrical Fields
1. Basic Concepts of Partial Discharge
宅急修
那么,是什么因素导致了这些绝缘材料内局部放电的发生呢?总体来讲,可以用一句话来概括:in gereral, the breakdown strength of local area in insulation is reached.绝缘体局部区域的电场强度达到了击穿场强。注意词组local area-局部区域一方面高压电气设备中的绝缘体各区域承受电场一般是不均匀的Non-uniform Electric Field,而且大部分复合材料电介质也是不均匀的Inhomogeneous dielectric medium。另一方面,即使单一的均匀材料,在制造或使用过程中会残留气泡和杂质(cavity and impurity),导致了绝缘体内部或表面出现某些区域电场强度高于平均电场强度,而某些区域的击穿场强低于平均击穿场强,因此在某些区域首先发生放电,其他区域保持绝缘特性。
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1.3 Damages to Insulation by Partial Discharges 1.3 Damages to Insulation by Partial Discharges
(1) (1) Bombardment of charged particle Bombardment of charged particle 带电质点轰击带电质点轰击
(2)(2) Thermal Effect Thermal Effect 热效应热效应
(3) (3) Resultant of Reaction Resultant of Reaction 反应生成物 反应生成物
PD Pulse width : 10-9-10-7 s , frequency band up to 1 GHz 。Frequency range of UHF : 300 MHz to 3GHz 。Advantages : to avoid noise frequency bands 。 Radio frequency band < 200 MHz;
Frequency band of corona < 300 MHz.
Light generated by PD in transformer oil has wavelength in the range from
Location with Electrical and Ultrasonic Methods 声电联合定位
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3. Objects and main subjects
To introduce how partial discharges occur and developoccur and develop in the insulation construction. To introduce the parametersparameters that describe partial discharges;局部放电在绝缘结构中的发生与发展,学习描述局部放电的参量 .
To introduce how partial discharges influence the propertiesinfluence the properties of insulation materials. To introduce how to evaluate PD behaviors and their damages damages to insulation materials. 学习局部放电对绝缘材料性能的影响,如何评估局部放电及其对绝缘材料的影响。
To introduce basic principlesbasic principles of PD detection and actual PD detection for high voltage devices. 局部放电检测的基本原理以及高压电气设备的局部放电测量方法。
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Meeting Topic Pages
1 Brief Introduction to Partial Discharge Detection;
[2] 1-11
2 Basic Concept of Partial Discharge Occurrence
Partial Discharge Recurrence at AC, DC and Impulse Voltages
[1] 1-28
[2] 13-22
3 Parameters to describe Partial Discharge Characteristics [1] 29-31
[2] 30
4 Influences on Properties of Insulation Materials by Partial
Discharges (1)
[2] 23-24
5 Influences on Properties of Insulation Materials by Partial
Discharges (2)
[2] 24-30
6 Basic Principle of Partial Discharge Detection (1)
[1] 36-48
[2] 41-43
7 Basic Principle of Partial Discharge Detection (2) [1] 50-72
[2] 34-40
3. Objects and main subjects
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8 Lab 1: Detection of Three types of PD models
9 Partial Discharge Detection in HV Capacitors [1] 153-156
[2] 46-50
10 Partial Discharge Detection in HV Cables [1] 157-161
[2] 46-50
11 Partial Discharge Detection in Transformers (1)
12 Partial Discharge Detection in Transformers (2)
[1] 146-170
[2] 61- 62
13 Partial Discharge Detection in HV Machines [1] 170-172