石化企业低压电动机电缆截面选择及校验

低压交流异步电动机在石油化工企业的用电负荷中占有很大的比重,电动机的点按选择是石油化工企业电气设计中的重要环节。随着工厂设计模式改革的深入和石油化工厂工艺装置处理量的不断提高以及大型联合装置的相继出现,使得装置变电所380V配电系统的供电距离越来越远,达到300~400米,甚至更长。供电距离增加后,线路阻抗增大,造成线路末端短路电流减小,导致常规配置的短路保护器无法满足短路保护灵敏度要求。文章通过具体实例就如何完成石油化工企业长距离供电的低压电动机的电缆选择及短路保护灵敏度校验做了相应分析。

Low-voltage AC asynchronous motor accounts for a large proportion in the electricity load of petrochemical enterprises,and the click selection of motor is an important link in the electrical design of petrochemical enterprises.With the deepening of the reform of factory design mode,the continuous improvement of the processing capacity of process units in petrochemical plants and the emergence of large-scale combined devices,the power supply distance of 380V distribution system in plant substation is getting farther and farther,reaching 300 to 400 meters,or even longer.With the increase of power supply distance,the line impedance increases,resulting in the decrease of short-circuit current at the end of the line,resulting in the conventional configuration of short-circuit protector can not meet the sensitivity requirements of short-circuit protection.Through specific examples,this paper makes a corresponding analysis on how to complete the cable selection and short-circuit protection sensitivity check of low-voltage motor with long-distance power supply in petrochemical enterprises.