、 电力 电缆 的敷设方式 I. Laying methods of power cables
电缆的敷设方式有 以下方式： 直埋敷设、穿管敷设、浅槽敷设、电缆沟敷设、电缆隧道敷设、架空敷设等 。 General power cables are laid in the following ways: direct buried laying, pipe laying, shallow groove laying, cable trench laying, cable tunnel laying, overhead laying, etc. 和 电缆隧道方式是最佳的敷设方式， 原因是 这两种方式便于电缆的施工、维护和检修。 Technically, the cable trench laying method and cable tunnel laying method are the best laying methods because the two methods are convenient for cable construction, maintenance, and repair. 在一些发达国家城市中，城市规划建设时，已 经 考虑公用隧道。 In some developed cities, public tunnels have been considered in urban planning and construction .
的 次数和反复开挖路面的现象，但 是 初期 的 投资 一般比较 大。 Practice has proved that public tunnels work well, greatly reducing the number of repeated investments and repeated road excavation, but the initial investment is generally relatively large. In China, due to various factors, such laying methods are rare. 是却 不利于电缆的维护和检修， 如果 遇到电缆故障 的时候 ，即使使用测试仪测出故障点，也要重新挖开电缆沟， 所以 极不方便。 In contrast, direct-buried laying and shallow-groove laying are economical laying methods, but they are not conducive to cable maintenance and repair. If a cable failure is encountered , even if the fault point is detected using a tester, It is very inconvenient to dig the cable trench again . Therefore, the selection of the cable laying method should be determined in accordance with the actual conditions, according to engineering conditions, environmental characteristics, cable types and quantities, and other developmental perspectives, in accordance with the requirements of operational reliability, easy maintenance and technical and economical rationality.
、 电力 电缆 的选型 Selection of power cables
常用的电力电缆有油浸电缆、聚氯乙烯绝缘电缆、交联聚乙烯电缆等， 而 根据使用场合的不同，又 可以 延伸为不同种类的特种电缆。 Generally used power cables include oil-immersed cables, PVC insulated cables, XLPE cables, etc., and can be extended to different types of special cables according to different applications . 该 根据使用的不同环境和条件，结合具体情况 来 进行选择， 比 如采用直埋和浅槽敷设方式 的 时 侯 ，应 该 考虑使用加钢铠的电缆。 At present, with the continuous improvement of production technology and production technology, cross-linked polyethylene cables have become the most widely used cable products. When selecting cables, they should be selected according to different environments and conditions of use and in combination with specific conditions . For example, when using direct buried and shallow trench laying methods , you should consider using steel armored cables.
、 电力 电缆 截面积的选择 Selection of cross-sectional area of power cables
The selection of the cable cross-sectional area is related to the amount of investment, the loss and voltage quality of the line, and the service life of the cable. 果 选用截面积偏小 的话 ，会导致电压质量下降、线路损耗过大，严重的甚至电缆 还会 过热烧毁； 如果选用 截面积过大 的话 ， 那么 会使初期投资太高。 If the cross-sectional area is too small , the voltage quality will be reduced, the line loss will be too large, and even the cable will be overheated. If the cross-sectional area is too large , the initial investment will be too high. 该 根据负荷预测结果，用发展的眼光，选择合适的截面积，使 得 电力电缆满足最大工作电流下的缆芯温度要求和电压降要求，最大短路电流作用下的热稳定要求。 Therefore, according to the results of load forecasting, with a development perspective, a suitable cross-sectional area should be selected so that the power cable can meet the requirements of the core temperature and voltage drop under the maximum working current, and the thermal stability requirements under the maximum short-circuit current. 在 选择电缆截面积 的 时 侯 ，还 必须 要满足《城市中低压配电网改造技术导则》和《城市电力网规划导则》 得 要求。 Due to the high difficulty and low accuracy of load forecasting, when selecting the cross-sectional area of the cable , it is necessary to meet the requirements of the "Technical Guidelines for the Transformation of Urban Medium and Low Voltage Distribution Networks" and "Guidelines for the Planning of Urban Power Networks" . .
同时 还要考虑零线截面积的选择 。 In the selection of power cables for the three-phase four-wire low-voltage power grid, the selection of the cross-section area of the zero line must also be considered . 因为 受用户因素影响较大， 所以 三相负荷平衡难以控制，为 了 改善电压质量，降低线损，零线截面积应 该 与相线截面积相同。 In public low-voltage networks, three-phase load balancing is difficult to control because it is greatly affected by user factors . In order to improve voltage quality and reduce line losses, the cross-sectional area of the zero line should be the same as the cross-sectional area of the phase line.
(To be continued)