Human detection thresholds of DC, AC, and hybrid electric fields: a double-blind study

Abstract

Background In the course of the ongoing transition of electric energy systems, transmission corridors are often upgraded to higher voltages and other technologies leading to another quality of human exposure. The study aims to determine human detection thresholds for direct current (DC), alternating current (AC), and hybrid electric fields (various DC; constant AC). Methods A total of 203 participants were exposed to DC, AC, and hybrid electric fields (EFs) in a highly specialized whole-body exposure laboratory using a double-blind experimental setting. Additionally, the participants were exposed to ion currents in part of the DC and hybrid sessions. To investigate environmental influences, relative humidity was changed in two subgroups during EF perception. Methods derived from the signal detection theory and the adaptive staircase procedure based on the single interval adjustment matrix were used to assess individual sensitivity and detection thresholds, respectively. Results The results indicated that detection thresholds of hybrid EF were lower compared to single EF presentation of DC or AC. Ion current exposure enhanced EF perception. High relative humidity facilitated DC EF perception, whereas low relative humidity reinforced the perception of AC EFs. Conclusions With this systematic investigation of human perception of DC, AC, and hybrid EFs, detection thresholds were provided, which can help improve the construction processes of energy transmission systems and the prevention of unwanted sensory perception by contributing to the determination of limit values.

The role of the AC component in human perception of AC–DC hybrid electric fields

“…This process of AC EF perception is thought to be facilitated by an increased relative permittivity of body hair 7 . Interestingly, in a recent study, we found that higher skin moisture did not result in facilitated EF perception, at least when it was assessed at a single measurement point before starting the EF perception testing 8 . Moreover, body surface sensibility seems to be another important factor influencing EF perception.…”

“…Moreover, body surface sensibility seems to be another important factor influencing EF perception. Kursawe et al recently demonstrated a relationship between vibrotactile measures (31 Hz and 63 Hz) and the detection of AC EFs and hybrid EFs 8 . The authors explained the correlation with hybrid EFs by the kind of evoked sensation, i.e., tingling, itching, or vibration and stressed the importance of body surface sensibility in the interaction mechanism of EF perception 8 .…”

“…Kursawe et al recently demonstrated a relationship between vibrotactile measures (31 Hz and 63 Hz) and the detection of AC EFs and hybrid EFs 8 . The authors explained the correlation with hybrid EFs by the kind of evoked sensation, i.e., tingling, itching, or vibration and stressed the importance of body surface sensibility in the interaction mechanism of EF perception 8 . Since large interindividual differences were found in human EF perception 3 , it is likely that differences in body surface sensibility or the length, structure, and relative permittivity of body hair all may influence individual EF perceptions.…”

“…Local EF exposure showed rather heterogeneous detection thresholds of about 375 kV/m for DC EFs and 8–33 kV/m for AC EFs 5 , 6 . Under whole-body exposure and laboratory conditions, DC detection thresholds were estimated between 18.7 and 45.1 kV/m and decreased when ion currents were simultaneously generated 8 , 9 . Whole-body exposure only to AC EF produced detection thresholds between 14 and 25 kV/m 4 , 8 .…”

“…Under whole-body exposure and laboratory conditions, DC detection thresholds were estimated between 18.7 and 45.1 kV/m and decreased when ion currents were simultaneously generated 8 , 9 . Whole-body exposure only to AC EF produced detection thresholds between 14 and 25 kV/m 4 , 8 . The first investigations of human perception of hybrid EFs from overhead test lines were conducted by Clairmont et al 10 .…”