上海市居民居室工频电磁场水平
Pilot Study on Power Frequency Electromagnetic Fields in Residence of Shanghai
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摘要:
目的 了解上海市居民的居室工频电磁场强度及其影响因素。 方法 采用KombiTEST场强仪,现场检测5种类型供电方式的125户居民居室家用电器关闭、开启两种工况下的工频电磁场强度。采用成组设计多样本比较的秩和检验,分析不同类型供电方式工频电磁场强度的差异;采用配对设计差值的符号秩和检验,比较两种工况工频电磁场强度的不同。 结果 在家用电器关闭、开启两种工况下,工频电场强度中位数从1 V/m上升到2 V/m,差异具有统计学意义(Z=24.791,P < 0.001);磁场强度中位数从0.023μT增加到0.035μT,差异具有统计学意义(Z=28.137,P < 0.001)。9户居民居室某一房间的工频磁场强度超过0.4 μT。5种类型供电方式居民居室中,电力线路跨越的民宅工频磁场强度水平最高,其次为采用三相或两相一地供电的别墅,其他三种供电方式居民居室较低;电力线路跨越的民宅磁场强度远高于三相或两相一地供电的别墅及其他三种供电方式的居民居室,差异具有统计学意义(家用电器关闭工况χ2=421.565,P < 0.001;家用电器开启工况χ2=265.575,P < 0.001)。 结论 居民居室附近的高压输电线路、户外低压配电线和室内配电布线及家用电器设备是居室工频磁场水平的主要电磁源。其中,高压输电线路和户外低压配电线对整个居室工频磁场水平的影响较大,而室内配电布线和家用电器设备的影响则比较有限。 Abstract:Objective To investigate the distributions of the level of electromagnetic fields in residence of Shanghai. Methods Power frequency electromagnetic fields of five different types of power line supply in 125 residences were assessed by conducting spot measurements with KombiTEST. Electromagnetic field levels with electricity appliances turned off were compared to that with electricity appliances turned on through paired-sample Wilcoxon signed rank test. Power frequency electromagnetic fields of 5 different types of power lines supply in residences were analyzed by nonparametric chi-square test. Results Average power-frequency electric field level was 3.100 V/m and power-frequency magnetic field level was 0.057 μT with all electricity appliances off, while average electric field level was 7.340 V/m and magnetic field level was 0.081 μT with all appliances on. Nine of the residences, approximately 7.2%, had one room there average magnetic field level with all appliances off was greater than 0.4μT. The average electric field level with appliances on was significantly higher than that with appliances off (Z=24.791, P < 0.001), meanwhile the average magnetic field level with appliances on was also dramatically greater than that with appliances off(Z=28.137, P<0.001). Power frequency magnetic field level in suburban residences near high-voltage transmission line was highest among 5 different types of power line supply. No matter that appliances were on or off, the difference of power frequency magnetic field level was significant among these five different types of power line supply(appliances off χ2=421.565, P < 0.001; appliances on χ2=265.575, P < 0.001). Conclusion High-voltage transmission lines, outdoor distribution lines, indoor power distribution wiring, grounding systems and appliances are main electromagnetic field sources. High-voltage transmission lines and outdoor distribution lines mainly influenc power frequency electromagnetic field level in the residences of Shanghai, while indoor power distribution wiring, grounding systems and appliances have a relatively limited impact on local areas.
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