An Assessment of the Electric Power Quality and Electrical Installation Impacts on Medical Electrical Equipment Operations at Health Care Facilities

Abstract

Problem statement: Medical electrical equipments at health care facilities presented malfunction and wrong medical information due to poor electric power quality and to inadequate electrical Installations. Some equipment such as X-ray, computerized axial tomography and magnetic resonance imaging are considered as polluting ones due to their high amount of harmonics and voltage transients produced on the electrical power supply when in operation, while other equipments, connected to the same power supply, are considered sensitive or victim ones, presenting failure or producing wrong. Approach: The effects on some sensitive medical electrical equipment were verified in a controlled environment at energy quality technological center of the technical school of the University of Sao Paulo. A heart monitor, pulmonary ventilator and pulse oxymeter equipment types were submitted to a controlled voltage supply with high harmonic content and voltage sags. The test methodology used simulated conditions based on Brazilian NBR standards, ANSI/IEEE Std. 519, IEC 60601 and IEC 61000-4-11 standards. Results: The results of the polluting equipment current consumption measurements as well as the three sensitive equipments tested were presented and discussed. The pulmonary ventilator presented problems that range from stoppage to expiratory valve blockage and alarm system failures. The pulse oxymeter presented display malfunctions and it was extremely sensitive to voltage sags. The heart monitor maintained steady operation in all test cases. Conclusion/Recommendations: In spite of several existing recommendations and standards for testing medical electrical equipments, there is a lack of standard related to test cases considering the effects of high harmonic and voltage sags. The quality of electrical installation in health care facilities needs to be improved to reduce risks to the patients and to provide better health treatment.