Authors L. M. Vedeneyeva, K. A. Chernyi
Month, Year 06, 2018 @en
Index UDC [614.825 + 331.45]:615.47
Abstract The use of medical electrical equipment and devices that allow for the implementation of modern methods of examination and treatment urgently require improved requirements to ensure the safety of patients and medical personnel. The aim of the work is to analyze the electrical safety of staff and patients in a medical institution and the reliability of medical electrical equipment. As is well known, a complex of protective measures against electric shock for a medical institution is determined taking into account the type of building power supply system, the class of medical equipment according to the degree of protection against electrical shock, the class of the medical room. When designing grounding devices for medical institutions, consideration should be given to all factors that may affect the effectiveness of protection and reliability of complex medical electrical equipment. The conductivity of soils is one of the most important of these factors and depends on the type, porosity (the ability of the rock to contain liquids and gases) and the structure of the soil, the degree of its humidity, temperature, degree of compaction, time of year, etc. The results of the study of the effect of the conductivity of soils on the values of their specific electrical resistance and, consequently, the resistance of grounding devices, which determine the safety of operation of medical electrical equipment, are presented. It is shown that the specific electrical resistance varies over wide ranges depending on different values of the porosity of the soil: for large values of the porosity of the soil, its specific electrical resistance decreases dramatically, since the pores can be filled with liquid, while increasing the conductivity of the soil. The calculation results are presented in the form of graphical dependences of the soil resistivity on the value of its porosity. So for sand it is shown that the limits of change of electrical resistance depending on its porosity, i.e. depending on the density of its installation, may vary by more than seventeen times. Based on the research conducted, it is reasonable that when designing grounding devices in medical institutions, it is necessary to take into account the porosity of soils in order to reduce the actual values of the resistances of grounding devices.

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Keywords Safety; medical electrical equipment; grounding; the specific electrical resistance of the soil; the porosity of the soil; the conductivity of the soil.
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