电缆额定电压的选择 Voltage designation 电缆额定电压应适合于电缆的系统的运行状况,用U0/U(Um)表示,均为有效值,单位为kv U0- 电缆设计用导体与屏蔽或金属套之间的额定工作电压; U—电缆设计用导体之间的额定工频电压; Um –设备可承受的“*高系统”电压的*大值。The rated voltage of the cable for a given application shall be suitable for the operating condition in the system in which the cable is used , and is expressed in the form of U0/U(Um)are applied to the system voltages and running state , and expressed in the form U0/Ukv.U0-The rated power-frequency voltage between conductor and earth or metallic screen ,for which the cable designed .U-The rated power –frequency voltage between conductors for which the cable designed.Um- –The maximum value of “the highest system voltage ”for which the equipment may be used.
三相系统用电缆的U0值推荐如下表:The values U0 recommended for cables to be used in three-phase systems are listed below:
环境条件对电缆载流量的修正系数Rating factors of current rating for ambient condition土壤敷设 Direct in ground 不同土壤温度下载流量修正系数 Rating factors of current rating for ambient temperature