在以太網(wǎng)和XDSL接入網(wǎng)設(shè)計中用到的RS-485接口的通訊電纜,經(jīng)常會碰到諸如24AWG、26AWG等等表示電纜直徑的方法。其實AWG(American Wire Gauge)是美制電線標(biāo)準(zhǔn)的簡稱,AWG值是導(dǎo)線厚度(以英寸計)的函數(shù)。下表是AWG與公制、英制單位的對照表。其中,4/0表示0000,3/0表示000,2/0表示00,1/0表示0。例如,常用的電話線直徑為24 AWG 的線徑約為0.5mm(0.2mm2),26AWG,約為0.4mm(0.13mm2),AWG數(shù)值越大線徑越小,平方越小。
美制AWG |
外徑 |
截面積(mm2) |
電阻值(W/km) |
美制AWG |
外徑 |
截面積(mm2) |
電阻值(W/km) |
||
公制mm |
英制inch |
公制mm |
英制inch |
||||||
4/0 |
11.68 |
0.46 |
107.22 |
0.17 |
22 |
0.643 |
0.0253 |
0.3247 |
54.3 |
3/0 |
10.40 |
0.4096 |
85.01 |
0.21 |
23 |
0.574 |
0.0226 |
0.2588 |
48.5 |
2/0 |
9.27 |
0.3648 |
67.43 |
0.26 |
24 |
0.511 |
0.0201 |
0.2047 |
89.4 |
1/0 |
8.25 |
0.3249 |
53.49 |
0.33 |
25 |
0.44 |
0.0179 |
0.1624 |
79.6 |
1 |
7.35 |
0.2893 |
42.41 |
0.42 |
26 |
0.404 |
0.0159 |
0.1281 |
143 |
2 |
6.54 |
0.2576 |
33.62 |
0.53 |
27 |
0.361 |
0.0142 |
0.1021 |
128 |
3 |
5.83 |
0.2294 |
26.67 |
0.66 |
28 |
0.32 |
0.0126 |
0.0804 |
227 |
4 |
5.19 |
0.2043 |
21.15 |
0.84 |
29 |
0.287 |
0.0113 |
0.0647 |
289 |
5 |
4.62 |
0.1819 |
16.77 |
1.06 |
30 |
0.254 |
0.0100 |
0.0507 |
361 |
6 |
4.11 |
0.1620 |
13.30 |
1.33 |
31 |
0.226 |
0.0089 |
0.0401 |
321 |
7 |
3.67 |
0.1443 |
10.55 |
1.68 |
32 |
0.203 |
0.0080 |
0.0316 |
583 |
8 |
3.26 |
0.1285 |
8.37 |
2.11 |
33 |
0.18 |
0.0071 |
0.0255 |
944 |
9 |
2.91 |
0.1144 |
6.63 |
2.67 |
34 |
0.16 |
0.0063 |
0.0201 |
956 |
10 |
2.59 |
0.1019 |
5.26 |
3.36 |
35 |
0.142 |
0.0056 |
0.0169 |
1,200 |
11 |
2.30 |
0.0907 |
4.17 |
4.24 |
36 |
0.127 |
0.0050 |
0.0127 |
1,530 |
12 |
2.05 |
0.0808 |
3.332 |
5.31 |
37 |
0.114 |
0.0045 |
0.0098 |
1,377 |
13 |
1.82 |
0.0720 |
2.627 |
6.69 |
38 |
0.102 |
0.0040 |
0.0081 |
2,400 |
14 |
1.63 |
0.0641 |
2.075 |
8.45 |
39 |
0.089 |
0.0035 |
0.0062 |
2,100 |
15 |
1.45 |
0.0571 |
1.646 |
10.6 |
40 |
0.079 |
0.0031 |
0.0049 |
4,080 |
16 |
1.29 |
0.0508 |
1.318 |
13.5 |
41 |
0.071 |
0.0028 |
0.0040 |
3,685 |
17 |
1.15 |
0.0453 |
1.026 |
16.3 |
42 |
0.064 |
0.0025 |
0.0032 |
6,300 |
18 |
1.02 |
0.0403 |
0.8107 |
21.4 |
43 |
0.056 |
0.0022 |
0.0025 |
5,544 |
19 |
0.912 |
0.0359 |
0.5667 |
26.9 |
44 |
0.051 |
0.0020 |
0.0020 |
10,200 |
20 |
0.813 |
0.0320 |
0.5189 |
33.9 |
45 |
0.046 |
0.0018 |
0.0016 |
9,180 |
21 |
0.724 |
0.0285 |
0.4116 |
42.7 |
46 |
0.041 |
0.0016 |
0.0013 |
16,300 |