文档介绍：1
Lecture 7 PD Detection in Power Capacitors
电力电容器的局部放电测量
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Contents
1. Partial Discharge in Power Capacitors
电力电容器中的局部放电
2. Parameters and Standard
测试参数及相关规程
3. Electrical Detection of PD in Capacitor
电力电容器的局部放电电测法
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1. Partial Discharge in Power Capacitors
the characteristics of power capacitors
Insulation structure of capacitors: oil-impregnated papers, oil-impregnated dielectric membrane and bination.
绝缘结构:油浸纸,浸渍薄膜及其组合
Extremely high electrical field stress exists in capacitors and partial discharges are very possible to occur inside.
介质工作场强特别高,内部特别容易发生局部放电
电力电容器的特点
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Inception and damage of PD in power capacitor
1. Partial Discharge in Power Capacitors
The lifetime of capacitor suffering from PD decreases exponentially.
PD is a key factor that results in expanding and incipient fault of power capacitor.
在局部放电作用下,寿命是随着电场的增加而呈指数形式下降的
局部放电是造成电容器膨胀和早期损坏的一个重要因素
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2. Parameters and Specification
Parameters to estimate the PD of capacitor
Apparent charge, q
Inception voltage, Ui
The AC voltage across the capacitor at which the discharge magnitude exceeds a given value qg.
视在放电量
升压过程中,观测到的放电量超过某个规定值时的最低电压
Inception voltage (stress): The AC voltage (stress) across the sample at which discharges start to occur when the voltage is increased .
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Extinction voltage, Ue
降压过程中,观测到放电量低于某个规定值的最高电压值。
The AC voltage across the capacitor at which the discharge magnitude is less than the given magnitude qg.
a is better than b
2. Parameters and Specification
Change of q with voltage applying time
放电量随加压时间的变化
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Procedure of PD detection
2. Parameters and Standards
U1:pre-applied Voltage 预加电压
Type
U1
(kV)
U2
(kV)
U3
(kV)
Requirement
Note
Shunt
capacitors
u
n
, 1s
u
n
,
10
min
u
n
, 10min
Series
-
connected
capacit
ors
4.
5
u
n
, 1s
u
n
, 1
0
min
Breaker
capacitors
u
n
, 1s
1.
1
u
n
,
10
min
D
uring last
10
min
, no PD
impulses with
increased