三相系統(tǒng)用電纜的U0值推薦如下表:
The values of U0 recommened for cable to be used in three-phase systems are listed below: |
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A類(lèi)系統(tǒng)──該類(lèi)系統(tǒng)任何一相導(dǎo)體與地和接地導(dǎo)體接觸時(shí),能在1min內(nèi)與系統(tǒng)分離
B類(lèi)系統(tǒng)──該類(lèi)系統(tǒng)僅包括單相接地故障短時(shí)運(yùn)行的條件,接地故障時(shí)間應(yīng)不超過(guò)1h, 但在任何情況下,最長(zhǎng)不超過(guò)8h每年接地故障總持續(xù)時(shí)間不超過(guò)125h; C類(lèi)系統(tǒng)──不屬于A類(lèi)、B類(lèi)的系統(tǒng)。 System category A──This category comprises those systems in which any phase conductor that comes in contact with earth or an earth conductor. is disconnected from the system within 1 min. System category B ──This category comprises those system which,under faultconditions,are operated,are operated for ashorttimewith one phase earthed.This period should not exceed 1 h..Fora longer period, not exceeding 8h on any occasion, can be tolerated.The total duration of earth faults in any year should not exceed 125h. System categeory C──This category comprises all systems which do not fall into A and B 電纜的型號(hào)Type of cable |
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導(dǎo)體標(biāo)稱(chēng)截面
|
絕緣
厚度 |
護(hù)套
厚度 |
電纜近似外徑
|
電纜近似重量
|
20℃
導(dǎo)體 |
電纜載流量
|
短路電流
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直流
電阻 |
在空
氣中 |
直埋土壤中
|
導(dǎo) 體
|
屏蔽層
|
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銅帶
|
銅絲
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mm 2
|
mm
|
mm
|
mm
|
kg/km
|
Ω/km
|
A
|
A
|
KA
|
KA
|
KA
|
3×25
|
3.4
|
2.4
|
48
|
3190
|
0.727
|
120
|
125
|
3.69
|
2.958
|
-
|
3×35
|
3.4
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2.5
|
50
|
3731
|
0.524
|
140
|
155
|
5.15
|
2.958
|
-
|
3×50
|
3.4
|
2.6
|
53
|
4396
|
0.387
|
165
|
180
|
7.31
|
2.958
|
-
|
3×70
|
3.4
|
2.7
|
57
|
5198
|
0.268
|
210
|
220
|
10.2
|
2.958
|
-
|
3×95
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3.4
|
2.9
|
62
|
6350
|
0.193
|
355
|
265
|
13.8
|
2.958
|
-
|
3×120
|
3.4
|
3
|
65
|
7257
|
0.153
|
290
|
300
|
17.4
|
2.958
|
-
|
3×150
|
3.4
|
3.1
|
69
|
8383
|
0.124
|
330
|
340
|
21.7
|
2.958
|
-
|
3×185
|
3.4
|
3.2
|
72
|
9741
|
0.0991
|
375
|
380
|
26.7
|
2.958
|
-
|
3×240
|
3.4
|
3.3
|
78
|
11854
|
0.0754
|
435
|
435
|
34.6
|
3.301
|
-
|
3×300
|
3.4
|
3.4
|
84
|
14861
|
0.0601
|
495
|
485
|
43.1
|
3.301
|
-
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