输变电设施电磁环境工频电场强度控制限值安全性分析

The Safety Analysis of Controlling Limit for Electromagnetic Environment of the Power Frequency Electric Field Strength of Power Transmission Facilities

决定电磁环境影响的两大因素是电磁强度和频率,对应交流输变电设施是工频电场强度和工频(50Hz)。电磁环境对人体健康的影响可分为"生物效应"和"健康影响"。根据国际非电离辐射防护委员会(ICNIRP)《限制时变电场、磁场和电磁场曝露的导则(300GHz以下)》说明,对于工频场的基本限值是感应电流密度,上述两者的分界值为100mA·m^(-2)。为避免"健康影响"的发生,保证安全,规定感应电流密度公众曝露控制限值为2mA·m^(-2),相当于工频电场5kV·m^(-1)曝露强度产生的结果,由此得出其安全系数为50。国家标准《电磁环境控制限值》(GB 8702-2014)规定了更为严格的控制限值为4kV·m^(-1)。由此,安全系数大于50,更具安全性。

The influence of electromagnetic environment was mainly determined by two factors,which were the electromagnetic intensity and frequency. The corresponding factors to the AC power transmission facilities were the electric field intensity and frequency( 50 Hz) of power frequency. The impact of electromagnetic environment on human health could be divided into "biological effects"and"health effects". According to the description of Guidelines for Limiting Exposure to Time-Varying Electric,Magnetic,and Electromagnetic Fields( up to 300 GHz) by the International Commission on Non-Ionizing Radiation Protection( ICNIRP),the basic limit of power frequency of the electric field was induced current density,the cutoff value of the mentioned effects was 100 mA·m^(-2). To avoid the occurrence of the "health effects"and ensure safety,the public exposure controlling limit value of induced current density should be 2 mA·m^(-2),which was equivalent to the result produced by the 5 kV·m^(-1) exposure intensity of electric field of power frequency,it followed that the safety factor was 50. The national standard Controlling Limits for Electromagnetic Environment provided a more stringent controlling limit value,which was 4 kV·m^(-1). Thus,the value of the safety factor was greater than 50,which was more safety.