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1

Research on the influence of power frequency electric field of pantograph on passengers’ health in high-speed EMU

Tian Rui, Zhang Jia-Qi, Lu Mai

Archives of Electrical Engineering

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2023

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Vol. 72, nr 2

483--501

EN

In this work we discussed the safety of the electric field environment in the No. 3 carriage where the pantograph is located. DSA380 pantograph, CRH5 EMU carriage and passengers’ models were established to study the electric field exposure of passengers at different positions. The results showed that Emax in the carriage without passengers is 1.173 x 10 6 mV/m. Then we set the passengers’ positions according to the electric field distribution in the carriage without passengers and obtained that Emax in the carriage with passengers is 3.195 x 10 6 mV/m. It can be seen that the maximum induced electric field intensity of passengers at different positions appears on the soles of shoes, the maximum value is 3.028 x 105 mV/m, the maximum induced current density occurs at the ankle, its maximum value is 3.476 x 10 -5 A/m 2. It can be concluded that the maximum induced electric field intensity of passenger’s head appears in the cerebrospinal fluid area, with a maximum value of 202.817 mV/m, and the maximum induced electric field intensity of passenger’s head at the door is larger than that in the middle of the carriage. The maximum values of the induced electric field intensity in all tissues of passengers are much smaller than the basic limits of electromagnetic exposure to the public set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). This study indicated that the pantograph has little influence on the electric field environment in the carriage under working state, and will not cause any health hazard to the passengers in this working frequency electric field environment.

2

Safety assessment of electromagnetic exposure for adult and child passengers standing on the subway platform

Li Jin, Lu Mai

Archives of Electrical Engineering

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2022

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Vol. 71, nr 3

755--773

EN

The objective of this work is to evaluate the safety of adult and child passengers exposed to a radio frequency (RF) source, i.e., a leaky coaxial cable (LCX) on the subway platform. An adult model, a child model, and an LCX model have been numerically designed in COMSOL Multiphysics software. The distributions of the induced electric field (E-field), specific absorption rate (SAR), magnetic field ( H-field) and the head temperature increase in adult and child passenger models were calculated at 900 MHz. The induced fields in the passengers were compared with that without screen doors. The results show that the E-field, SAR and H-field in the whole body of the child are 2.00 × 10 -2 V/m, 1.07 × 10 -7 W/kg, and 2.94 × 10 -4 A/m, respectively. The E-field, SAR and H-field in the central nervous system of the child are 1.00e × 10 -2 V/m, 2.44 × 10 -8 W/kg, and 2.41 × 10 -4 A/m, respectively. The maximum values of the E-field, SAR and H-field in the adult passenger are 1.49–2.34 times higher than those of the child. The E-field, SAR, and H-field in the passenger models without a screen door are larger than those with a screen door. The screen door has a partial shielding effect on the RF electromagnetic field. The values of the maximum temperature that increases in adult and child head tissue are 0.2114 and 0.2111℃ after waiting 6 minutes exposure, respectively. All calculated results are well below the International Commission on Non-Ionizing Radiation Protection (ICNIRP) limits for general public exposure, indicating that RF electromagnetic exposure caused by the LCX on the subway platform is not a threat to passenger’s health.

3

Study on the distribution of SAR and temperature in human brain during radio-frequency cosmetic treatment

Qi Xinzhe, Lu Mai

Archives of Electrical Engineering

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2021

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Vol. 70, nr 1

115-127

EN

This paper established a radio-frequency electrode model and human head modelused in RF cosmetic instruments. The distribution of electric field strength, a specific absorption rate (SAR), and temperature distribution in the human brain at 1 MHz and 6 MHz were studied and the results compared with the International Commission on Non-ionizing Radiation Protection (ICNIRP) guidelines. The results showed that under those two frequencies the maximum value of electric field strength in the human brain was 1.52 V/mand it was about 5.4% of the ICNIRP basic restrictions, the maximum SAR in human brain was about 2.21×10−3W/kg, which was far less than 2 W/kg of ICNIRP basic restrictions, the maximum temperature of the human brain was 37.6 located in the wounded skin, which was the same as the normal temperature 37. Since all the results were within the ICNIRP basic restrictions, the electromagnetic exposure generated by the RF cosmetic electrode will not pose a threat to the human health.

4

Safety evaluation for a high signal operator with electric field exposure induced by contact wires

Yang Chang-Qiong, Lu Mai

Archives of Electrical Engineering

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2021

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Vol. 70, nr 2

431--444

EN

To evaluate the occupational safety of a high signal operator exposed to the electric field induced by contact wires with a frequency of 50 Hz and a voltage of 27.5 kV, this study established a model of a high signal operator working in the vicinity of single and double-track railways. The electric field distribution in the operator’s body and his head were calculated and analyzed during the operation using the finite element method (FEM). The calculated results were compared with the international standard occupational exposure limits formulated by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) and action levels (ALs), exposure limit values (ELVs) in Directive 2013/35/EU (EU Directive). In the case of a single-track railway exposure, the maximum electric field strength in the worker’s body, in the scalp layer, and inside the brain are 227 mV/m, 2.76 kV/m, and 0.14 mV/m, respectively. For a double-track railway exposure, the maximum internal electric field strength of the operator is 310 mV/m, which is 37.85% of the occupational exposure basic restriction limit. The maximum electric field strength in the head layers is 3.42 kV/m, which is 34.2% of the occupational exposure reference level and 34.2% of the low ALs. The maximum electric field strength of the brain is 0.19 mV/m, which is 0.19% of the occupational basic restriction limit and 0.135% of the sensory effects ELVs. Results show that the electric field exposure of the high signal operator to contact wires in single- and double-track railways is lower than the occupational exposure limits provided by the ICNIRP and EU Directive standards and is thus regarded as safe for workers.