Analysis of electromagnetic compatibility standards for medical devices
Publisher: Administrator Date：2022-05-30
With the development and use of more and more medical devices, how to solve the problem of electromagnetic compatibility of medical devices, it is very important and urgent to improve the reliability and safety of medical devices. It is a research topic. This article analyzes the basic classification of electromagnetic compatibility issues, the harm of electromagnetic compatibility, and the basic requirements of the electromagnetic compatibility standards for medical electronics equipment.
Electromagnetic compatibility (EMC) refers to the ability to run normally in the electromagnetic environment without causing unacceptable electromagnetic interference in the environment in the electromagnetic environment. Electromagnetic compatibility standards are the requirements of this function of equipment or systems. The implementation of the electromagnetic compatibility standards for medical devices will improve the safety and effectiveness of medical devices so that they will not be controlled by electromagnetic interference or harassment during use. When investigating the electromagnetic compatibility of the equipment or system, the source, path and device or system should be analyzed. The sources of interference will generate electromagnetic interference, which will act on equipment or systems that are disturbed through specific paths. The interference may have the consequences after being disturbed by electromagnetic interference. As a acceptable risk result, this is the tolerance of the victim's equipment or system. It should be noted that the interference equipment or system is also a source of interference. Many modern equipment or systems that use electronic technology generate electromagnetic waves during normal operation and interfere with other equipment or systems to a certain extent. .. From the perspective of path analysis, it is not only transmitted through air communication (high frequency), but also through electric wires and cables (low frequency).
It is generally believed that if the system meets the following three standards, it is considered that the system is compatible with electromagnetic compatibility: (1) not being disturbed by other systems (electromagnetic interference, EMI); (2) not affected by other system radiation (electromagnetic sensitivity, EMS) ; (3) Don't disturb yourself. According to the above standards, the electromagnetic compatibility requirements of equipment or system electromagnetic compatibility standards usually limit the level of interference of equipment or systems. That is, the electromagnetic launch capacity of the interference source is limited (at the same time also limits the source of the device or system. The system's anti -interference level is the ability to resist interference, specifically depending on the environment and the environment) requires that the equipment or system (improved the acceptance of the affected by the environment and the environment) Abroad for interference equipment), the state regulatory authorities often pay more attention to the EMI launch capacity of restricting the source of interference. It is suggested that the company itself guarantees the level of the interference equipment. In our country, national regulatory agencies test EMI and EMS to make equipment safer to people. It is underway.
1. EMC standard related to medical equipment
The electromagnetic compatibility criteria related to medical devices include: YY 0505-2012 "Part 1-2 of Medical Electric Equipment: Common Safety Requirements for Medical Electric Equipment and Systems" standard: electromagnetic compatibility requirements and tests; GB/T 18268.1-2010 " Part 1 of the use of electromagnetic compatibility, control and laboratory of electrical equipment: GM requires "testing and diagnosis of medical electrical equipment and GB/T18268.26-2010" electrical equipment measurement, control and laboratory electromagnetic compatibility requirements. Part 26: In vitro diagnosis (IVD) medical special requirements equipment "; these special requirements are either a standard part or a standard for electromagnetic compatibility, such as GB/T25102.13. EMC).
The National Food and Drug Administration announced on December 17, 2012, YY 0505-2012 announced that it will be implemented on January 1, 2014, and the electromagnetic compatibility content that is specially released is included in the standard. In addition, it will continue quickly. Implement. At the same time, the announcement clearly states that the electromagnetic compatibility test for medical electrical equipment used to detect diagnosis should also refer to this standard. Embed. Other special standards must be implemented in accordance with the standard implementation time and corresponding requirements.
2. YY0505 medical electrical equipment and system standards
YY 0505-2012 is equivalent to GB9706.1-2007 "Medical Electric Equipment Components" IEC60601-1-2: 2004 (2.1). 1: The parallel standard of "General Safety Requirements" is also a general standard. It is suitable for all equipment and systems that do not specify EMCs without special standards or special standards, but it is not applicable to implanted medical electricity. equipment. The electromagnetic compatibility standards of implanted medical electrical equipment have not been announced. This standard specifies the electromagnetic compatibility requirements and testing of equipment and systems, which is the basis for electromagnetic compatibility requirements and testing in special standards. This standard specifies the external mark, attachment files and electromagnetic compatibility levels of equipment or systems.
2.111 Main test items
In the electromagnetic compatibility test, according to the transmission of electromagnetic energy, the EMI and EMS problems can be divided into four basic EMC sub -problems. Radiation and conduction sensitivity, as shown in Figure 2. YY 0505 has designed a total of 11 tests to verify the electromagnetic compatibility of the system according to the four different energy transfer methods of electromagnetic energy. Among them, conductive launch, harmonic current, voltage fluctuations, and flash change are conductive launch tests. Radioactive launch is a radioactive launch test, anti -static discharge, electrical high -speed sudden resistance, surge resistance, voltage drop, and short -term blocking resistance. Essence The sensitivity test for performed; anti -interference, anti -radiation field radiation, and anti -working frequency field radiation of radio frequency induction are radiation sensitivity tests. The following are 11 tests.
2.1.1 conduction and radiation emission
When the medical equipment is running normally, the electromagnetic can be radiated from the cable and the surrounding space at the same time. Low -frequency electromagnetic waves between 0.15 and 30 MHz are mainly radiating energy through cable. Electromagnetic waves from 30 MHz to 1 GHz or even 1 GHz are mainly radiating energy through space medium. If radiation energy is received by other medical electronics equipment, it may cause the device to fail and affect the operation of other equipment. To this end, many national standards stipulate the methods and restrictions of measurement of electromagnetic radiation. Simple motor driver equipment or system refers to GB 4343.1, and lighting equipment or system refers to GB 17734. Information technology equipment or system GB 9254 is cited, and GB 4824 is referenced to other devices or systems other than the above devices or systems. Quoting the equipment or systems of GB4824 and GB9254 should also be classified according to the location of the equipment. Non -home equipment access to the residential low -voltage power supply network can access Class A equipment, household equipment and direct residential low -voltage power supply network. For category B, Class B emissions limit is stricter than Class A emissions.
2.1.2 Harmonic current launch, voltage flash, fluctuation
These two requirements limited the effects or systems running on the power network.
The harmonic current launch limit refers to GB17625.1. The root cause of the harmonic in the grid in the power grid is to use a large number of non -linear loads during the design of medical equipment. When the current flows through the load, it has a non -linear relationship with the applied voltage and generates a harmonious current in the circuit. The emergence of harmonics will reduce the efficiency of power use, so that medical equipment is overheated, noise, accelerate insulation and degradation, shorten the service life, and even cause faults or burns. Generally speaking, strange harmonics are more harmful than the occurrence of sub -harmonics, so this standard has increased the requirements of strange harmonic waves so that medical equipment will not overwhelm the public power grid. Please note that YY 0505 does not require equipment or systems with a current of more than 16 A per phase.
See GB17625.2 for voltage flash and fluctuation limit. In the case of high -power medical electricity equipment, due to the significant increase or decrease of load current, the voltage changes quickly. The difference between the maximum voltage and minimum voltage of the voltage regulatory wave is called voltage fluctuation. .. Voltage fluctuations and related voltage flash medical devices are unstable, lights and darkness, affecting normal production, life, and even personal health. Therefore, the voltage fluctuations and flashing inhibit in the allowable range.
2.1.3 Anti -static discharge ESD
There are many factors that cause charge accumulation, such as contact pressure, friction coefficient and separation. At this time, if you touch the medical electronic equipment, the electrostatic will be passed on the device, and the arc will be generated between your fingertips and equipment. Direct charge transfer will cause permanent damage to electronic components such as integrated circuit chips and cause system failures. Static discharge (ESD) is a very common problem today. According to the requirements of YY 0505, the two forms of air and contact exhaust are designed. For air discharge, the device must withstand ± 2 kV, ± 4 kv and ± 8 kv, and contact discharge can withstand ± 2. Kitter, ± 4 kV and ± 8 kV. 6KV. The test method refers to GB/17626.2.
2.1.4 RF anti -electromagnetic field radiation
Today's environment is full of electromagnetic fields of different frequencies, including radio, television, fixed or mobile radio transmitters, and electromagnetic fields generated by different industries. source. The medical equipment running in the electromagnetic field will be exposed to the electromagnetic field, affecting the normal operation of the equipment. YY0505 radio frequency electromagnetic radiation resistance level requires that the non -life maintenance system or the system or the system can withstand 3V/m interference field strong in the frequency range of 80MHz to 2.5GHz, and the life maintenance system or system must reach 10V/m. The test method refers to GB/17626.3.
2.1.5 Electrical high -speed blast resistance
When a high -power inductance load, switch or relay switch on the power network, it will generate fast transient pulse interference with a large amount of energy, and couples to the power port, signal and control to affect the operation of ports and equipment or systems. The requirements of YY0505 for electrical high -speed emergencies are that AC and DC power cords can withstand ± 2 kV. Signal cables with more than 3 m and interconnected cables can withstand ± 1 kV. The test method refers to GB/17626.4.
2.1.6 waves of waves
The electromagnetic field generated by lightning will cause high -energy transient in the power line, and the same phenomenon will also occur when turning on and off high -power loads. This high -energy transient voltage will affect equipment or systems along the power line. The requirements for YY0505 anti -wave surge levels are to bear ± 0.5kV, ± 1kV, ± 2kV to the ground to the ground. .. Test method refers to GB/17626.5.
2.1.7 Anti -transmission interference of RF guidance
If the electromagnetic field radiation frequency received by the device or system is low, the electromagnetic wave will generate conduction interference in the cable, affecting the operation of the device or system. The tolerance level of conduction interference caused by YY 0505 radio frequency should be within the frequency range of 150 kHz to 80 MHz. Non -life support systems or systems can withstand 3VRMS interference, as well as life support systems or systems. It is disturbed by 10VRMS in engineering, science and medical bands. The test method refers to GB/17626.6.
2.1.8 voltage drop and short -term interrupt capacity
If the grid fails or major changes in load, the power supply will be restored after a short interruption or the voltage decrease. It will affect the normal operation of the device or system in a short time. YY 0505 analyzes the voltage drop through the results of the test system in three different cases: the voltage drops 95%, the duration is 10 ms, the voltage drops 60%, the duration is 100 ms, the voltage drops 30%, and the duration is 500 ms. immunity. The short -term cut -off tolerance of the device is analyzed by the test results of the system in the case of the voltage deadline. The test method refers to GB/17626.11.
2.1.9 Removal of industrial frequency magnetic field
When the operating frequency current flows through the conductor, a specific magnetic field will be generated around it, affecting some equipment and systems that are very sensitive to the magnetic field. YY 0505 needs to have a certain degree of tolerance to the industrial frequency magnetic field in order to be disturbed under the intensity of 3 A/M magnetic field. The test method refers to GB/17626.8.
The above 11 compulsory tests are referred to the corresponding national standards. YY 0505 proposes specific testing requirements based on the particularity of medical devices. Through the simulation signal to simulate the normal operation of the device or system, the simulated hand must be used at the junction of the patient, and the electromagnetic field of the device or system in the normal operation process must be performed at the junction of the patient. Compatibility study. The requirements of YY 0505 Antipatement level not only meet the higher levels of reference standards, but also put forward higher -level requirements for certain projects of life support systems. However, although the standard allows equipment or systems to be less than standard requirements, it must be acceptable due to important physical, technical or physiological restrictions. In order to determine the results of immunology testing, YY0505 uses 36.202.1J as the general compliance standard. It lists a set of phenomena that does not occur when the device or system is disturbed (including equipment failure). Interference diagnosis or monitoring parameters, changes in operating mode, misunderstanding, waveform noise or image distortion.
2.2 External marking and random file requirements
It should be noted that YY 0505 attaches great importance to the requirements of external markings and random files. Although the mark can play a prompt and warning role, random files have an irreplaceable effect on the user's understanding, use and maintenance of equipment or systems.
YY 0505 has three requirements for external signs. ① Non -ionized radiation mark. This shows that the equipment or system actively generates high -frequency electromagnetic waves, and pay attention to its impact on peripheral equipment in use. ② For equipment. The connectors exempt from the system static test should indicate that the internal static movies are obtained from the connector, and preventive measures described in random files should be adopted. In addition, the system should be used in the following position: the specified shielding position.
The random files of YY 0505 include prompts, warnings and some forms. The packaging instructions should include warnings on equipment or system location, application of radio frequency, accessories that affect electromagnetic compatibility, and other matters that need to be kept in mind during use. Observing this information and warning is essential for your equipment or system security. Electromagnetic compatibility plays an important role.
3. GB/T18268.1 and GB/T18268.26 Medical Electric Equipment Inspection and Diagnosis
The inspection and diagnosis of medical electrical equipment mainly include biological microscopes, PCR amplifiers, enzyme label meters in clinical laboratories or devices used in clinical laboratories. In clinical laboratory. YY 0505 is not suitable for such devices, but requires two standards: GB/T18268.1 and GB/T18268.26. GB/T 18268.1 standards stipulate the electromagnetic compatibility test configuration, working conditions, test requirements, interference limit and exemptional statement of testing and diagnosis of medical electrical equipment. The quoted electromagnetic compatibility standards are basically the same as YY0505. GB/T 18268.1 According to the immune testing level of the use place, such as industrial land and controlled electromagnetic circuits, different requirements have been put forward. At the same time, the performance standards of each antipity test are clearly defined to determine its compliance. GB/T 18268.1 Divides performance standards into three categories: A, B, and C. These corresponding behaviors, deviations, self -repair, operator intervention, or system reset during the test period. Among them, C phenomenon is not allowed in the device used in the controlled electromagnetic environment.
GB/T 18268.26 [9] Standard is suitable for in vitro diagnostic (IVD) equipment, which is a special requirement for electromagnetic compatibility of in vitro diagnostic products. This has a different antidomy requirements with GB/T18268.1. This is because the risk of using in vitro diagnostic medical devices is similar to the risk of maintaining medical devices for non -life. The standard stipulates that the same immune testing requirements are the same as maintaining medical devices as non -life. See the relevant standards for the content of the resistance.
Four. Thinking and conclusions
4.1 Some special national and industry standards
Including the standards that have not yet released, a total of 31 domestic and industry standards have proposed electromagnetic compatibility. Different electromagnetic compatibility requirements from YY 0505 include high -frequency, microwave, ultrasonic, endoscopy, hearing aid, ventilator, electrocardiogram, monitoring, defibrillation, X -ray, nuclear magnetic and other equipment. .. These standards are either different from the requirements for YY 0505, or have specific requirements in the standard, or there are specific regulations in the test arrangement. Due to the large number, this article will not be explained one by one.
4.2 EMC live test technology
Electromagnetic on -site testing (also known as on -site testing) is a test that moves the EMC test device to the place where the product is running. The EMC test requires the shielding room and the Dark Dark Room, but with the development of electronic technology, it is necessary to perform electromagnetic compatibility tests on increasingly larger medical equipment such as PT, PET-CT, NMR. These large instruments cannot be successfully tested in closed laboratories because they have large volume, the load capacity that exceeds the shielding or the sound room, or is permanently connected to the power supply. How to evaluate EMC performance.
On -site testing is facing restrictions on the complexity of electromagnetic environment and many types of system components. Therefore, on -site test assessment includes serious environmental interference, difficult evaluation, unstable results, low test data utilization, and reasons for identification interference. There are various problems, so you need to be careful.
4.3 Basic Performance of EMC Test
YY0505-2012 introduces the concept of "basic performance". In other words, the anti -interference testing and evaluation of medical electrical equipment only targets "basic performance". \\ Basic performance of the test. However, as the functions of various medical equipment are increasingly integrated, we must consider establishing basic performance. Taking multi -parameter guardians as an example, the mainstream equipment on the market currently includes ECG, heart rate, non -invasive/blood pressure, single single, single single, single single, single single, single single, single single, single single, single single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, single, and single. Reading/double reading temperature, blood -like saturation, breathing and other parameters. Measurement. Therefore, the basic performance should be determined according to the expected use of the product. It is obtained through risk analysis and emphasized that these properties can be expected. Fully installed in the electromagnetic environment without led to decline or loss.
4.4 Model and unit coverage problem
Like electrical safety, the electromagnetic compatibility also has the problem of whether the model and component can cover other models. However, because the electromagnetic field is not visible, the electromagnetic compatibility model is more cumbersome than electrical safety and lack of experience. Therefore, this issue needs to be further investigated and discussed.
The YY0505 standard and related electromagnetic compatibility standards implemented since 2014 are of great significance to the medical device industry. There is no doubt that this will be a huge driving force for improving the quality of medical device products, promoting and protecting product upgrades. product Safety. This process requires the cooperation of equipment or system manufacturers, test units or users to provide electromagnetic compatibility for medical equipment. Helps the smooth implementation of content standards.
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