40台工频电场测量仪器实验室间比对研究
Inter-laboratory comparison study on 40 power frequency electric field measuring instruments
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摘要:
目的 通过工频电场测量仪器的实验室间比对，了解广东省职业卫生技术服务机构工频电场测量仪器的配置、校准情况及性能。
方法 以广东省40家职业卫生技术服务机构（以下简称"参比机构"）的40台工频电场测量仪器（以下简称"参比仪器"）为研究对象，查验其校准证书。以某变压器为标准源，组织方用同一台仪器在距离其1.0 m处进行不同时间段的检测，采用单因素方差分析法检验其稳定性。在稳定性检验后，由参比机构测量人员持参比仪器在距离标准源1.5 m和2.0 m的测量点进行比对检测，采用基于四分位数稳健统计技术的z比分数对测量结果进行分析。
结果 标准源稳定性检验中，第1天下午、第2天上午、第2天下午共3个时间段电场强度比较，差异无统计学意义（209.52±0.38）、（209.96±0.51）和（209.74±0.60）V/m，P>0.05，表明标准源可满足实验室间比对的稳定性要求。40台参比仪器中有1台参比仪器未送检，2台参比仪器校准证书已过期，1台参比仪器校准结果超出允差范围。40台参比仪器实验室间z比分数（zB）为-1.16~13.41，实验室内z比分数（zW）为-1.29~25.26；其中2台参比仪器|zB|及|zW|均>3.00，1台参比仪器|zB|>3.00，为离群结果；4台参比仪器|zB|或|zW|>2.00，为有问题结果。根据比对结果，判定3台参比仪器不合格。
结论 以变压器为标准源进行工频电场测量仪器的实验室间比对具有可行性，目前广东省职业卫生技术服务机构配置的工频电场测量仪器在使用上仍存在一定的问题。
Abstract:Objective To understand the configuration, calibration, and performance of power frequency electric field measuring in struments in Guangdong occupational hygiene technical service agencies by inter-laboratory comparison.
Methods Forty power frequency electric field measuring instruments were selected from 40 occupational hygiene technical service agencies in Guangdong Province, and calibration certificates were examined. Using a transformer as standard source, measurements were conducted at 1.0 m distance from the transformer at different time periods, and homogeneity was evaluated by one-way ANOVA. Spot measurements were then conducted at 1.5 m and 2.0 m distance from the standard source by surveyors from each agency using respective measuring instrument, and the measurement results were analyzed by z-score.
Results Homogeneity analysis results showed that there was no statistical difference in electric field intensity among three selected time periods(209.52±0.38), (209.96±0.51), and (209.74±0.60) V/m for afternoon of the first day, morning of the second day, and afternoon of the second day, respectively, P > 0.05, indicating that the standard source was qualified for inter-laboratory comparison in terms of stability. One measuring instrument was unable to provide calibration certificate, calibration certificates of two instruments were expired, and one instrument's calibration result was not within tolerance range. The inter-laboratory z-score (zB) of 40 measuring instruments ranged from -1.16 to 13.41, while the intra-laboratory z-score (zW) ranged from -1.29 to 25.26. Both|zB|and|zW|of two instruments were above 3.00, and the|zB|of another instrument was above 3.00, indicating outliers; the|zB|or|zW|of four instruments were above 2.00, indicating problematic results. In light of those results, three instruments were unqualified.
Conclusion It is feasible that a transformer could be applied as standard source in inter-laboratory comparison of power frequency electric field measuring instruments. There are still problems in the use of power frequency electric field measuring in struments in Guangdong occupational hygiene technical service agencies.
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