Low Voltage Leakage Protection And Monitoring Of Medical Electrical Room Shanghai Jiao Tong University

With the development of science technology, modern medical treatment has used more and more electrical and electron devices to treat patient. When the electrical level of hospital became higher and higher, these high technical electrical devices has a higher requirement to hospital electrical environment, especially in today's medical treatment. Some past designing can not meet the requirement of safety, so more and more electrical engineers have paid attention to the low voltage system of hospital and leakage of medical devices. Especially in operation, many medical electrical devices connects with body bowel and brain, if electrical leakage happened, the result can not be imagined.So how to ensure the medical electrical devices to use reliably, how to protect the patient and hospital staff from leakage accident became very important, and many specialists and doctors pay attention to this. Many countries and international standards regulate some special standards to hospital electrical room, especial to some important room, for example operation room, ICU and etc. And it will ensure that to provide a safe and reliable power to ensure the doctor and patient safe.According to standard IEC 60364-7-710 (GB 16895.24-2005), go deep to research the residual current monitor system, single phase AC medical IT system and insulation faulty location system.For the residual current monitor system, it is applied for monitoring three phases or single phase system's leakage current. It takes node current principle, monitor every load or residual current, and current transformer is assembled every branch to collect the leakage current signal of downstream circuit, and then transfer to residual current monitor and then display in the panel of control and display.For the single phase AC medical IT system, analyze the safety of IT system in medical electrical room and analyze the principle design and insulation monitor of IT system, and then design the single phase AC medical IT system which has been used in this project. In this project, the insulation monitor has been connected between IT system and earth, monitoring the insulation resistance to the earth continuously. When insulation resistance exceeds the limiting value, an alarm is initiated, and the insulation monitor can not only monitor the insulation resistance to the earth but also monitor the load current and temperature of transformer. In actual project, if the exceeds the limiting value (insulation resistance, load current and temperature), the alarm relay switched, the alarm LED lights up and a message appears on the LC display.For the insulation faulty location system, it was designed on the base of single phase AC medical IT system, only adds the insulation faulty evaluator. When single phase AC medical IT system has an insulation, insulation monitor will have a massage of alarm, and then insulation faulty evaluator can locate the fault location in time. And it is convenient for the work staffs know the system status and remove the faulty in time. And it could ensure the single phase AC medical IT system safety and reliably.