三相系统用电缆的U0值推荐如下表:
The values of U0 recommened for cable to be used in three-phase systems are listed below: |
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A类系统──该类系统任何一相导体与地和接地导体接触时,能在1min内与系统分离
B类系统──该类系统仅包括单相接地故障短时运行的条件,接地故障时间应不超过1h, 但在任何情况下,最长不超过8h每年接地故障总持续时间不超过125h; C类系统──不属于A类、B类的系统。 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 电缆的型号Type of cable |
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导体标称截面
|
绝缘
厚度 |
护套
厚度 |
电缆近似外径
|
电缆近似重量
|
20℃
导体 |
电缆载流量
|
短路电流
|
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直流
电阻 |
在空
气中 |
直埋土壤中
|
导 体
|
屏蔽层
|
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铜带
|
铜丝
|
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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
|
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
|
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
|
-
|