论控制系统对接地电阻值的要求

Discussion on Requirement of Grounding Resistance Value for Control System

控制系统对接地电阻值有其自身的要求,而目前国内许多控制系统的制造商仍以4Ω作为对接地电阻值的要求。通过分析认为:控制机柜内设备在发生故障时,空气开关或熔断器的动作电流以及土壤或地面的电阻率决定了控制机柜保护地对接地电阻值大小的要求;控制系统的绝缘性能与对称性能决定了工作地对接地电阻值大小的要求。控制系统的工作地与控制机柜的保护地对接地电阻值的要求是有差异的,设计过程中接地电阻的期望值应小于两者中的较小值。

The grounding resistance value of control system has its own reqmrements. Nowadays, 4Ω as the requirement of grounding resistance value is still used in many manufacturers of control system in China. Through analysis, requirements of protection grounding to grounding resistance value for control cabinet is determined by action current of air switch or fuse and resistivity of soil （or ground） when the fault of equipment in a cabinet happened. Requirements of working ground to grounding resistance value is determined by insulation performance and symmetrical performance of control system. The requirements of the working grounding resistance value for control system differ from that of the protection grounding. The expected value of grounding resistance value for an engineering design should be less than one of the smaller.