Xu Shuang Ankerui Electric Co., Ltd. Shanghai Jiading 201801 Abstract This paper mainly introduces the differences between IEC standards and NSPF standards represented by the United States in the field of medical IT systems, and further understands the different leakage protection technologies of application and medical IT systems. Keywords leakage current insulation monitoring IEC standard NSPF standard medical IT system Type 2 medical sites are important places in the hospital, usually operating rooms, intensive care units, or cardiac care rooms. They are places of vital importance to patients and are also places full of medical devices and medical electrical equipment. Leakage protection has special requirements compared to ordinary buildings, that is, through local IT systems. In order to better understand the different leakage protection technologies applied to medical IT systems, first introduce the current relevant international standards. 1 Different standards of medical IT systems in different countries The main countries and their national standards for adopting medical IT systems in medical type 2 places are as follows: United States NFPA 99 Switzerland MED 4818 United Kingdom BS7671-SGN7.10 (2003) Hungary MSZ2040 Germany DIN VDE 710 Belgium TN013 France NF C15-211 Brazil NBR13.543 Netherlands NEN 3134 Chile N.SEG 4EP79 Italy TC 10 Canada CSAZ31.1 Austria OVE-EN7 Japan JIS T 1022 Norway NVE-1991-FEB Australia AS3003 Finland SFS 4372 China GB 16895.24 - 2005 Spain UNE20-615-80 International Electrotechnical Commission (IEC) IEC60364-7-710 Ireland TC 10 A review of the specifications of the aforementioned countries can be divided into two major standards, namely the standard for monitoring the insulation value of the IT system against the ground, represented by IEC60364-7-710. The main participating countries are mostly EU countries such as the United Kingdom and France. Germany, Finland, Italy, Switzerland, Hungary, Ireland, etc. Outside the European Union countries such as China and Brazil. The other standard, represented by NEPA99 in the United States, monitors the sum of capacitive leakage currents and resistive leakage currents of IT systems. The main countries followed are Canada, Japan, Australia, the Netherlands, Norway, Chile, and many Central American countries. 2. Medical smart insulation monitor The IEC60364 standard stipulates that for medical electrical equipment used for life-supporting or surgical operations in medical Class 2 sites, equipment with a rated voltage exceeding AC25V or DC60V must use an IT power supply system with an insulation monitor. Figure 1 Ankerui Medical Intelligent Insulation Monitor The medical intelligent insulation monitor is installed between the IT system and the earth. When the IT system is grounded, the insulation monitor immediately sends an alarm signal notifying the operator that the system has been running with a fault. The fault must be found as soon as possible so that the second point can be grounded. Troubleshooting before. For the insulation monitor installed in the IT system of the medical type 2 site, in addition to the general standard IEC 61557-8 of the insulation monitor, the special requirements of the IEC 60364-7-710 standard must also be met: 1. Internal internal impedance should be at least 100kΩ; 2. The test voltage should not be greater than DC 25V; 3. Even in the fault conditions, the peak value of the injected current should not exceed 1mA; 4. The signal should be generated at the latest when the insulation resistance drops to 50kΩ, and instruments that test this function should be configured; 5. The Insulation Monitor signals when the ground is interrupted or the electrical line is interrupted. 3. Measuring principle of insulation monitor (IMD) The measurement principle of the insulation monitor is shown in Figure 1. Figure 2 Measuring principle of insulation monitor The AIM-M100 medical insulation monitor is connected to the monitored system by an internal coupling resistor RA. The signal source G inside the insulation monitor sends a measurement voltage signal which is superimposed between the monitored system and the ground (PE line) through the coupling resistance RA, the measurement resistance Rm and the low-pass filter circuit. The measurement voltage passes through the external IT system pair. The total insulation impedance RF of the ground constitutes the measurement loop, so the total insulation resistance of the monitored system to ground is obtained by measuring the measurement current Im in the loop. The traditional application and measurement of AC system ground insulation resistance insulation monitor often use DC signal measurement method, the relevant circuit diagram can be simplified into Figure 2; Figure 3 Simplified circuit diagram The insulation monitor sends a constant current measurement voltage signal. The measurement current Im generated by the insulation resistance of the system and the insulation resistance of the system to ground become linear. The relationship is as follows: By measuring the measured current Im, the insulation resistance Rf of the system to ground can be easily obtained. However, this measurement method is easily affected by the DC load current in the monitored system and the AC currents of various frequencies. Therefore, the improved insulation monitor uses the method of superimposing pulse measurement voltage to measure the insulation value of the IT system against the ground. In the last 20 years due to the rapid development of computer technology, ACREL used low-frequency AC signals to measure the insulation resistance of the system. The amplitude and frequency of the measurement signal are controlled by a single-chip microcomputer and can accurately measure the insulation resistance and system capacitance of the current system. Through extensive application in hospitals around the world, it has proven to be a reliable method of measuring insulation on-line. 4. Application Plan of Medical Intelligent Insulation Monitor in Medical Class 2 Locations The scheme of applying the medical intelligent insulation monitor in the actual field is shown in Figure 4 and Figure 5, and the scheme configuration is shown in Table 1 and Table 2: Figure 4 Operating room isolated power system solution diagram Scheme configuration table Table 2 Isolation Power System Solution Configuration for ICU 5 Quotation plans for main products and power cabinets In order to facilitate our customers' choice of Acryle products, we now list product quotation, as shown in the following table: 5.1 GGF-I Series ICU/CCU Ward Isolation Power Cabinet shape model specification unit Price (ten thousand yuan) GGF-I3.15 3.15KVA set 3.8~5.3 GGF-I6.3 6.3KVA set 4.4~5.9 GGF-I8 8KVA set 5~7 GGF-I10 10KVA set 6.8~9.8 ups Optional, additional price Dual power switching device Optional, additional price Freight Reference logistics company quote Note The above quotation includes commissioning fees, excluding freight and installation fees 5.2 GGF-O Series Operating Room Isolated Power Supply Cabinet shape model specification unit Price (ten thousand yuan) GGF-O6.3 6.3KVA set 6.4~7.9* GGF-O8 8KVA set 7~9* GGF-O10 10KVA set 8.6~11.6* ups Optional, additional price Dual power switching device Optional, additional price Freight Reference logistics company quote Note The above quotation includes commissioning fees, excluding freight and installation fees 5.3 Medical IT Insulation Monitoring Products shape name model Features price Optional and price (yuan) Insulation monitor AIM-M100 IT system ground insulation resistance, load current, transformer temperature monitoring 15600 AIM-M200 19600 DC power supply ACLP10-24 Instrument dedicated power supply 300 / Alarm and display AID100 Insulation resistance, transformer load rate; remotely set the insulation monitor alarm threshold / AID120 / AID200 Using CAN communication, can remotely display and set the parameters of up to 16 sets of insulation monitoring system, real-time monitoring whether the communication is in good condition 900 / Current Transformer AKH0.66-P26 Real-time measurement of transformer load current 150 / Test signal generator ASG100 Using CAN bus technology, data exchange with other devices can occur. When an insulation fault occurs in the system, a fault location signal can be injected into the system to achieve L1, L2 disconnection detection. 3780 / Fault location (evaluation) instrument AIL100-4 Adopt CAN bus technology, when the insulation fault occurs in the system, it can cooperate with ASG100 to realize fault location function 6050 / AIL100-8 8050 / 6. Some optimization measures in practical application 2. In order to both take into account the practicality of IEC specifications and to minimize capacitive currents in IT systems, the IEC 60364-7-710 standard strictly stipulates that the capacity of isolation transformers must not exceed 10 kVA, which can prevent to a certain extent Medical IT systems that use very long lines. 3. IEC standard isolation transformers have a relatively low inrush current, which reduces the need for an automatic power switching device for the IT system's front stage. The IEC 61558-2-15 standard specifies the isolation transformers. The isolation transformers complying with this specification have relatively small volume and low noise level. The inrush current is less than 12 times the rated current, and the small inrush current is undoubtedly the opposite. The requirements of the UPS connected to the primary of the isolation transformer are reduced. In order to meet the low level ground leakage current requirements of the US standard isolation transformer, isolation transformers often have high noise, and the inrush current is often about 20 times of the rated current. In practice, a set of UPS devices is often connected to multiple isolation transformers. The higher the inrush current of the isolation transformer, the higher the cost of the UPS backup power supply. 7. Conclusion In summary, in the field of medical IT systems, IEC specifications have strong practicality and are widely accepted and adopted worldwide. The NSPF standard represented by the United States is more stringent than the IEC standard, and the difficulty and cost of implementing the standard are higher than the IEC standard. references: [1]Leakage detection and application of medical IT system. Intelligent building electrical technology 2010.3 [2] Ankerui Electric Co., Ltd. Product Selection Manual 2013.1. About the Author: Xu Shuang, female, undergraduate, Ankerui Electric Co., Ltd., the main research direction for the smart grid power distribution, Email: Mobile QQ Curved Bar,Curved Wet Bar,Bar Curved,Curved Corner Bar Nantong Dongfang fitness equipment Co., Ltd , https://www.dongfangfitness.com
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1. There is no strict regulation on the placement of isolation transformers for medical IT systems. The location of the isolation transformer determines the distance from the transformer to the system load (medical electrical equipment). The longer the distance, the greater the capacitive current generated by the circuit. The U.S. standard IT system isolation transformer is usually mounted in the wall of the operating room to reduce the distance from the transformer to the medical electrical equipment. To meet Canada's stricter regulations, the isolation transformer of the operating room is suspended on the operating bed like a pylon. Its purpose is also to reduce the capacitive leakage current. In the standards of Australia and Japan, it is stipulated that the cable from the transformer to the operating room does not allow the use of metal conduit, but also for the same purpose. Regardless of whether the transformer is placed inside the operating room, whether it is embedded or suspended, it has hindered the requirement of air cleanliness of the operating room; at the same time, the capacity of the transformer cannot be too large, which also limits the flexibility of the operating room function. If the plastic threading tube is placed in the ceiling of the operating room, the reliability of the electrical installation will be reduced. The IEC specification stipulates that the IT system isolation transformer can be located outside the operating room, which greatly reduces the difficulty of electrical installation, and at the same time it is also very beneficial to the heat dissipation of the transformer.