Leakage currents, tiny currents flowing from an everyday-life appliance through the body to the ground, can cause a non-adequate perception (called electrocutaneous sensation, ECS) or even pain and should be avoided.Safety standards for low-frequency range are based on experimental results of current thresholds of electrocutaneous sensations, which however show a wide range between about 50 μA (rms) and 1000 μA (rms). In order to be able to explain these differences, the perception threshold was measured repeatedly in experiments with test persons under identical experimental setup, but by means of different methods (measuring strategies), namely: direct adjustment, classical threshold as amperage of 50% perception probability, and confidence rating procedure of signal detection theory. The current is injected using a 1 cm2 electrode at the highly touch sensitive part of the index fingertip.These investigations show for the first time that the threshold of electrocutaneous sensations is influenced both by adaptation to the non-adequate stimulus and individual, emotional factors. Therefore, classical methods, on which the majority of the safety investigations are based, cannot be used to determine a leakage current threshold.The confidence rating procedure of the modern signal detection theory yields a value of 179.5 μA (rms) at 50 Hz power supply net frequency as the lower end of the 95% confidence range considering the variance in the investigated group. This value is expected to be free of adaptation influences, and is distinctly lower than the European limits and supports the stricter regulations of Canada and USA.
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机译:泄漏电流是日常生活用具从人体流到地面的微小电流,可能会导致不适感(称为电皮肤感觉,ECS)甚至疼痛,应避免使用。低频范围的安全标准是基于电流的电流阈值的实验结果,显示在大约50μA(rms)和1000μA(rms)之间。为了能够解释这些差异,在具有相同实验设置的测试人员的实验中重复测量了感知阈值,但是通过不同的方法(测量策略)进行了测量,即:直接调整,经典阈值作为50%感知的安培数信号检测理论的概率和置信度评定程序。使用1 cm 2 sup>电极在食指的高度触敏部位注入电流。这些研究首次表明,电刺激的阈值受非接触性适应的影响。足够的刺激和个人,情感因素。因此,不能将大多数安全研究所基于的经典方法用于确定泄漏电流阈值。现代信号检测理论的置信度评估程序在50 Hz电源下产生的值为179.5μA(rms)净频率作为95%置信范围的下限,考虑到研究组的差异。预期该值不受适应影响,并且明显低于欧洲限制,并支持加拿大和美国的更严格规定。
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