我发表一点个人看法(仅供参考):

1 用户想提高电缆绝缘的安全裕度.

2 在地下敷设如果是垂直敷设(例如煤矿)有可能用增加厚度来增强其抗拉性能.

注:怎么不问一下用户呢,问到了发贴告诉我,我也学习一下.

具不完全了解，这是国外的一些特殊要求的线，我也是略知一二：

关于百分比的问题结实如下：国外要求的100%的绝缘厚度其实就是国内4.5的厚度，还有的要求是120%，133%等等的，这好象是线路规定的等级的大小不同所制。

我看这主要是用户使用的系统有关系，由于各国的电压系统不同引起的．ＩＥＣ６０５０２中规定了Ａ＼Ｂ＼Ｃ三类系统，其中Ｃ类要求最高，用户要求在8.7/10KV基础上加１３３％，刚好接近Ｃ类的１２／２０ＫＶ等级．这是我的看法不知当否？

xinpeng:
也可能跟国外电力系统频率有关,我国的都是50HZ,而国外的就不一样,有60HZ的或更高的,所以对电缆的要求也会提高!

频率不同，电缆厚度不会相差这么大。

这跟电压系统，类似ＩＥＣ６０５０２中规定了Ａ＼Ｂ＼Ｃ三类系统，其中Ｃ类要求最高，绝缘厚度就厚。

给大家一个15KV系统的结构参数实例。

1/3 NEUTRAL <DIV align=right>15KV 100% INSULATION LEVEL </DIV>
Conductors		Insulation Thickness (MILS)	Insulation OD Inches	1/3 Neutral		Jacket Thickness (MILS)	Approx. Cable OD Inches	Approx. Net Wt. Lbs/M Ft.	Ampacity?/b>
SIZE (AWG or kcm)	Number of Strands			No. of Wires	AWG				Condition A	Condition B
2	7	175	0.70	6	14	50	1.04	402	125	155
1	19	175	0.74	6	14	50	1.08	435	140	175
1/0	19	175	0.78	6	14	50	1.12	475	160	200
2/0	19	175	0.83	7	14	50	1.17	534	185	225
3/0	19	175	0.88	9	14	50	1.22	615	210	260
4/0	19	175	0.93	11	14	50	1.28	707	235	290
250	37	175	0.98	13	14	50	1.33	784	260	320
350	37	175	1.08	18	14	50	1.46	1009	310	385
500	37	175	1.21	16	12	50	1.63	1305	375	460
750	61	175	1.39	15	10	80	1.93	1839	455	555
1000	61	175	1.54	16	9	80	2.15	2368	525	620

FULL NEUTRAL <DIV align=right>15KV 100% INSULATION LEVEL </DIV>
Conductors		Insulation Thickness (MILS)	Insulation OD Inches	Full Neutral		Jacket Thickness (MILS)	Approx. Cable OD Inches	Approx. Net Wt. Lbs/M Ft.	Ampacity?/b>
SIZE (AWG or kcm)	Number of Strands			No. of Wires	AWG				Condition A	Condition B
2	7	175	0.70	10	14	50	1.04	450	125	155
1	19	175	0.74	13	14	50	1.08	519	140	175
1/0	19	175	0.78	16	14	50	1.12	594	160	200
2/0	19	175	0.83	13	12	50	1.21	699	185	225
3/0	19	175	0.88	16	12	50	1.26	81	210	260
4/0	19	175	0.93	13	10	50	1.36	972	235	290
250	37	175	0.98	16	10	50	1.41	1115	260	320
350	37	175	1.08	16	9	50	1.57	1408	310	385

<DIV align=right></DIV>

<DIV align=right>15kv 133% Insulation Levels, 1/C Aluminum, EPR Insulation, 1/3 Neutral and Full Neutral, Encapsulating Plyethylene Jacket.</DIV>

1/3 NEUTRAL <DIV align=right>15KV 133% INSULATION LEVEL </DIV>
Conductors		Insulation Thickness (MILS)	Insulation OD Inches	1/3 Neutral		Jacket Thickness (MILS)	Approx. Cable OD Inches	Approx. Net Wt. Lbs/M Ft.	Ampacity?/b>
SIZE (AWG or kcm)	Number of Strands			No. of Wires	AWG				Condition A	Condition B
2	7	220	0.79	6	14	50	1.14	467	125	155
1	19	220	0.83	6	14	50	1.18	503	140	175
1/0	19	220	0.87	6	14	50	1.22	546	160	200
2/0	19	220	0.92	7	14	50	1.26	608	185	225
3/0	19	220	0.97	9	14	50	1.32	692	210	260
4/0	19	220	1.02	11	14	50	1.40	811	235	290
250	37	220	1.07	13	14	50	1.45	892	260	320
350	37	220	1.17	18	14	50	1.56	1104	310	385
500	37	220	1.30	16	12	80	1.79	1473	375	460
750	61	220	1.48	15	10	80	2.02	1960	455	555
1000	61	220	1.63	16	9	80	2.25	2502	525	620

FULL NEUTRAL <DIV align=right>15KV 133% INSULATION LEVEL </DIV>
Conductors		Insulation Thickness (MILS)	Insulation OD Inches	Full Neutral		Jacket Thickness (MILS)	Approx. Cable OD Inches	Approx. Net Wt. Lbs/M Ft.	Ampacity?/b>
SIZE (AWG or kcm)	Number of Strands			No. of Wires	AWG				Condition A	Condition B
2	7	220	0.79	10	14	50	1.14	515	125	155
1	19	220	0.83	13	14	50	1.18	587	140	175
1/0	19	220	0.87	16	14	50	1.22	665	160	200
2/0	19	220	0.92	13	12	50	1.30	773	185	225
3/0	19	220	0.97	16	12	50	1.35	890	210	260
4/0	19	220	1.02	13	10	50	1.48	1076	235	290
250	37	220	1.07	16	10	50	1.53	1224	260	320
350	37	220	1.17	16	9	50	1.66	1503	310	385

目前我公司为国外用户提供的中压电缆多数标准为12/20KV,有的用户要求铜屏蔽层全部是铜丝!

跟电缆接地故障时间有关,按照IEC标准,应该是电缆接地的C类系统,A类为100%水平,B类为115%水平,C类为133%水平!

这是根据电力系统的接地方式对电缆绝缘耐压能力的要求决定的.

Go check the ICEA S-94-649-2004 standard (page 21). For 100% level, cable in this category may be applied where the system is provided with relay protection such that ground faults will be cleared as rapidly as possible, but in any case within 1 minutes. And for 133% level,  a little bit longer, but not exceeding 1 hour. Hope it's helpful.

我个人理解， 这是企业标准， 企业所在地的安全试验要求高

上面的绝缘皮厚标准值得借鉴.

安全裕度问题，美国标准就是要考核1.33倍电性能。

100 Percent Level - Cables in this category may be applied where the system is provided withrelay protection such that ground faults will be cleared as rapidly aspossible, but in any case within 1 minute. While these cables are applicable tothe great majority of cable installations that are on grounded systems, theymay be used also on other systems for which the application of cable isacceptable provided the above clearing requirements are met in completelyde-energizing the faulting section.

Where additional insulation thickness is desired, it shall be the same asfor the 133 percent insulation level.

133 Percent Level - This insulation level corresponds to that formerly designated forungrounded systems. Cables in this category may be applied in situations wherethe clearing time requirements of the 100 percent level category cannot be met,and yet there is adequate assurance that the faulted section will bede-energized in a time not exceeding 1 hour. Also they may be used whenadditional insulation strength over the 100 percent level category isdesirable.

有技术要求，和产品检验规范不就知道了吗？

国外的系统跟我们不一样,电压等级要求也不一样,所以,他们是根据自己国家的电压等级来要求绝缘厚度的,不用想那么多,不会是为了增加预度的,我们的国标里,留得预度够大的了.

我觉得还是系统耐压的问题，可能电压要高一些，相同的电压下，国外的绝缘厚度都要薄一些

我认为跟接地系统有关

如果是电阻接地或直接接地用100%  如果是消弧圈接地用133%厚度

个人意见

请见如下权威解释：

the cable standards refer to 100%, 133% and 173% insulation levels. the 100% insulation level is suitable for systems which provide immediate isolation when an earth fault occurs. the time limit is 1 minute. for longer period of up to 1 hour, the 133% issulation level is suitable. if a phase is anticipated to remain earthed indefinitely, or presumably for more than 1 hour, the 173% level applies.

可见，133%的绝缘水平，为故障时间为1分至1小时。超过1小时，或时间不确定，当采用173%的绝缘水平。

        这个问题其实看是简单：是国外标准要求的，不过中压电缆的使用环境和高压、低压不同。至于绝缘皮厚要求133%这个数据是一个查考数值。这个是专家提出的数据我们暂时不能改，就用着好了，我个人意见

美国标准对3类绝缘水平的规定：

100%绝缘水平：故障切除时间不超过1min，用于直接接地或经小电阻接地系统中

133%绝缘水平：故障切除时间不超过1h，用于直消弧线圈或不接地系统中

173%绝缘水平：故障时间可以任意长，不作具体规定

根据美国标准和中国标准的规定，可以看出绝缘采用哪个绝缘水平是和系统的接地方式有关，发生故障时电缆本体承受的电压有关系。

我们有个菲律宾客户专门订这样的线，但都是单芯的１０ＫＶ和３５ＫＶ

增加133%是按B类系统设计的，这种系统的变压器中性点是经过消弧线圈接地，具有一定的阻抗。在输出端一相接地短路时，变压器中性点向接地一相偏移，但偏移量不大。理论上偏移量介于A类系统（中性点直接接地）和C类系统（中性点不接地）之间，根据消弧线圈的阻抗情况，所以规定设计电压为原额定电压的1.33倍，也就是楼主所述的绝缘厚度要厚上133%。

删除错误讯息

修正楼上的

应该要依据美国National Electrical Code的定义(NFPA 70我手上是2017版)

100 Percent Insulation Level. Cables in this category shall be permitted to be applied where the system is provided with relay protection such that

ground faults will be cleared as rapidly as possible but, in any case, within 1 minute. While these cables are applicable to the great majority of cable

installations that are on grounded systems, they shall be permitted to be used also on other systems for which the application of cables is acceptable,

provided the above clearing requirements are met in completely de-energizing the faulted section.

2 133 Percent Insulation Level. This insulation level corresponds to that formerly designated for ungrounded systems. Cables in this category shall be

permitted to be applied in situations where the clearing time requirements of the 100 percent level category cannot be met and yet there is adequate

assurance that the faulted section will be de-energized in a time not exceeding 1 hour. Also, they shall be permitted to be used in 100 percent insulation

level applications where additional insulation is desirable.

3 173 Percent Insulation Level. Cables in this category shall be permitted to be applied under all of the following conditions:

(1) In industrial establishments where the conditions of maintenance and supervision ensure that only qualified persons service the installation

(2) Where the fault clearing time requirements of the 133 percent level category cannot be met

(3) Where an orderly shutdown is essential to protect equipment and personnel

(4) There is adequate assurance that the faulted section will be de-energized in an orderly shutdown

Also, cables with this insulation thickness shall be permitted to be used in 100 or 133 percent insulation level applications where additional insulation

strength is desirable.