With the development of electrical and electronic technology, the increasing popularity of household appliances and electronic products, radio and television, post and telecommunications and computer networks are increasingly developed, the electromagnetic environment is increasingly complex and deterioration, so that the electrical and electronic products, electromagnetic compatibility (EMC electromagnetic interference EMI and electromagnetic resistance EMS) issues have been the growing attention of the countries *** and production enterprises. Electronic, electrical products electromagnetic compatibility (EMC) is a very important quality indicators, it is not only related to the product itself, the reliability of the work and the use of safety, but also may affect the normal operation of other equipment and systems, the relationship between the protection of the electromagnetic environment. In order to standardize the electromagnetic compatibility of electronic products, all developed countries and some developing countries have formulated electromagnetic compatibility standards. EMC standards are the basic requirements to enable products to work properly in the actual electromagnetic environment. The reason why they are called basic requirements means that even if a product meets the EMC standards, interference problems may occur in actual use. Most national standards are based on those developed by the International Electrotechnical Commission (IEC).
The European *** body *** stipulates that from January 1, 1996, all electrical and electronic products must be certified by EMC, affixed with the CE mark before they can be sold in the European *** body market. This move has caused a wide impact in the world, countries *** have taken measures to implement mandatory management of the EMC performance of electrical and electronic products. Internationally more influential, such as the EU Directive 2004/108/EC (i.e., EMC Directive), the U.S. Code of Federal Regulations CFR 47/FCC Rules, etc. have put forward a clear requirement for electromagnetic compatibility certification.
Standard1: GB 4343-1995 "Household and similar electric, electric heating appliances, power tools and similar electrical radio interference characteristics of the measurement method and allowable values" The standard was released on August 25, 1995, December 1, 1996 onwards.
2: GB4343.2-1999 "electromagnetic compatibility household appliances, power tools and similar appliances, the requirements of the second part of the immunity" The standard was released on March 23, 1999, April 1, 2000 onwards.
3:GB 17625.1-2003 "Low-voltage electrical and electronic equipment issued by the harmonic current limits (equipment per phase current ￡ 16A equipment)" The standard was released on February 09, 2003, May 01, 2003 onwards. Replaces GB 17625.1-1998.
Content
To make the product has good electromagnetic compatibility, need to specifically consider the design content related to electromagnetic compatibility. EMC design generally includes the following aspects.
Ground designMany electromagnetic interference problems are generated by the ground, because the ground potential is the reference potential of the entire circuit work, if the ground is not properly designed, the ground potential is unstable, which will lead to circuit failure. The purpose of ground design is to ensure that the ground potential is as stable as possible, thereby eliminating interference phenomena.
Circuit board designWhether the device produces electromagnetic interference emissions or the impact of external interference, or between the circuit produces mutual interference, circuit board is the core of the problem, so the design of the circuit board to ensure that the electromagnetic compatibility of the device is of great significance. The purpose of the circuit board design is to reduce the circuit board on the electromagnetic radiation and sensitivity to external interference, reduce the circuit board between the mutual influence.
Filtering designFor any device, filtering is one of the key technologies to solve electromagnetic interference. Because the wires in the device is a very efficient receiving and radiating antenna, therefore, most of the radiation generated by the device is transmitted through a variety of wires to achieve, and external interference is often the first to be received by the wires, and then strung into the device. The purpose of filtering is to eliminate these interference signals on the wire, to prevent the circuit of interference signals to the wire, with the help of the wire radiation, but also to prevent the wire received interference signals into the circuit.
Prohibition and lap designFor most devices, prohibition is necessary. Especially with the increasing frequency of circuit operation, purely rely on circuit board design often can not meet the requirements of electromagnetic compatibility standards. There are many differences between the prohibited design of the chassis and the traditional structural design. Generally, if the electromagnetic prohibited requirements are not considered in the structural design, it is difficult to add the prohibited effect to the chassis. Therefore, for modern electronic product design, must be considered from the beginning to prohibit the problem.
Inspection itemsElectromagnetic emission (EMI) of the test items are:
Electromagnetic emission (EMI) of the test items are:
①. Conductivity (CE) (150kHz~30MHz);
②. Intermittent Interference Voltage (click) (150kHz, 500kHz, 1.4 MHz and 30MHz);
③. Interference power (30MHz~300MHz)
④. Harmonic current (2~40th harmonic)
Flicker
Electromagnetic immunity (EMS) test items are:
①. Electrostatic discharge immunity;
②. Radiated electromagnetic field (80MHz~1000 MHz) immunity;
③. Electrical fast transient/pulse group immunity;
④. Surge (lightning strike) immunity;
⑤. Current Injection (150kHz~230MHz) immunity;
⑥. Voltage drop and short-term interruption immunity
Certification1. For the format of EMC certification application, please refer to China EMC Certification Center: Application Materials>>;
2. A copy of Business License of Enterprise Legal Person or registration certificate of enterprise applying for the certification;
3. Stable quality of the product and the proof of mass production capacity;
4. The proof of application for the certification. p>
4. the quality manual of the applicant enterprise;
5. two copies of the production process overview of the product for certification;
6. product specifications;
7. two copies of the description of the product structure;
8. the product electrical schematic diagrams and printed circuit board diagrams;
9. two copies of the product EMC key parts list (stamped);
9. product EMC key components (seal);
10. Official seal);
10. need to provide other relevant information when requested
I. EMC certification sampling and determination rules
1, in 30 to 50 sampling mother randomly selected 4 samples, of which 3 samples for inspection, 1 sample for the enterprise to retain for inspection; mother of the number of cases greater than 50 units, can be randomly determined as 50 samples Sampling mother.
2, the enterprise from the test of the three samples arbitrarily extracted from a sample sent to the designated EMC testing laboratory for testing, the test results than the certification of the implementation of the standard limit value of 2dB to determine the tightening.
3, if a single sample of the measurement results to meet the requirements than the certification standards for the implementation of the limit value of 2dB strict, it is determined that the sample test passes.
4, if a single sample of the measurement results do not meet the requirements of the certification and implementation of the standard limits, the sample test is judged unqualified.
5, if a single sample of the measurement results to meet the certification and implementation standards set out in the limits of the requirements, but not to meet the certification and implementation standards than the limit value of 2dB strict requirements, the enterprise should be extracted from the other two samples sent to the testing organization for inspection, if the results of the two samples sent to meet the certification and implementation of the standards set out in the limits of the requirements, it is ruled that the sample test passes, or else ruled that the sample test is unqualified. Qualified.
II. Relevant laws and regulations
The Law on EMC
Classic Portrayal of Justice From 1 January 1996 most electrical and electronic products, including all types of high frequency, DC & servo drives and similar control equipment, made and sold in the EC, including imports, have to be:
● So constructed that they do not cause excessive electromagic interference and are not unduly affected by electromagic interference.
● Carry the CE (Communauté Européene) quality assured mark.
In some cases a technical construction file must be drawn up and kept available, generally by the manufacturer, or the importer from a non-Chinese manufacturer, or the importer from a non-Chinese manufacturer, or the importer from a non-Chinese manufacturer.
Failure to comply with these requirements:
●Will mean that those electrical or electronic products may be prohibited from being placed in the CE (Communauté Européene quality assured mark). products may be prohibited from being placed on the Community market (18 European Countries), and will be withdrawn if previously placed on the market1
●Could result in penalties prising imprisonment for a term not exceeding 3 months or a fine not exceeding £5,000 or both
Three. Three Important Laws
1) Law 1: EMC cost-effectiveness ratio: The earlier the EMC problem is considered and solved, the smaller the cost and the better the result.
EMC design in the new product development phase, than to wait until the product EMC test failed to improve, the cost can be greatly saved, the efficiency can be greatly improved; on the contrary, the efficiency will be greatly reduced, the cost will be greatly increased.
Experience tells us that the functional design of the EMC design at the same time, to the prototype, prototype completion through the EMC test, is the most time-saving and most cost-effective. On the contrary, the product development stage does not consider the EMC, production after the discovery of EMC failed to improve, not only on the technology to bring great difficulty, and rework is bound to bring a great waste of money and time, and even due to the defects related to the structural design, PCB design, can not be implemented to improve the measures, resulting in the product can not be marketed.
2) Rule 2: The larger the high-frequency current loop area S, the more severe the EMI radiation.
High-frequency signal current flows through the inductor minimum path. When the frequency is high, the general alignment reactance is greater than the resistance, the connection to the high-frequency signal is inductive, series inductance caused by radiation. Electromagnetic radiation is mostly EUT equipment under test on the high-frequency current loop generated by the worst case is the antenna form of open circuit. Corresponding treatment is to reduce, shorten the connection, reduce the area of the high-frequency current loop, try to eliminate any non-normal working needs of the antenna, such as discontinuous wiring or antenna effect of the components of the long pins.
One of the most important tasks to reduce radiation nuisance or improve RF radiation immunity is to find ways to reduce the high-frequency current loop area S.
3) Law III, the higher the loop current frequency f, caused by EMI radiation is more serious, the electromagnetic radiation field strength with the frequency of the current f square proportional to the increase.
The most important way to reduce radiation nuisance or improve the anti-jamming ability of RF radiation is to find ways to reduce the source of the nuisance high-frequency current frequency f, that is, to reduce the frequency of the nuisance electromagnetic wave.
Fourth, the national standards of EMC technology
National standards of electromagnetic compatibility technology, also known as (electromagnetic compatibility national standard, EMC national standard)
Basic standards
GB/T 4365-1995 Electromagnetic compatibility terminology
GB/T 6113-1995 Specification for Radio Interference and Immunity Measuring Equipment
GB 3907--83* Basic Measurement Methods for Industrial Radio Interference
GB 4859--84* Basic Measurement Methods for Dryness and Immunity of Electrical Equipment
GB/T 15658-1995 Measurement Methods for Radio Noise in Cities
General Standards
GB 8702-88 Provisions on Protection against Electromagnetic Radiation
GB GB/T 13926.1--92 Electromagnetic compatibility of industrial process measuring and control devices
GB/T 13926.2--92 Electromagnetic compatibility of industrial process measuring and control devices for electrostatic discharge requirements
GB/T 13926.3--92 Electromagnetic compatibility of industrial process measuring and control devices for radiated electromagnetic fields
GB/T 13926.4--92 Electromagnetic compatibility requirements for industrial process measurement and control devices for electrically fast transient pulse groups
GB/T 14431--93 Signal/interference protection ratios and minimum usable field strengths for radio service requirements
Product categoryGB 4343-1995 Household and similar electric, electric heating appliances, power tools and similar electrical appliances. Measurement methods and permissible values for radio interference characteristics of electrical appliances
GB 4824-1996 Measurement methods and limit values for electromagnetic nuisance characteristics of industrial, scientific and medical (ISM) radio-frequency equipment
GB 6833.1--86* General provisions of the test specification for electromagnetic compatibility of electrical measuring instruments
GB 6833.2--87* Electrical measuring instruments Electromagnetic compatibility test specification Magnetic field sensitivity test
GB 6833.3--87* Electromagnetic compatibility test specification for electronic measuring instruments Electrostatic discharge sensitivity test
GB 6833.4--87* Electromagnetic compatibility test specification for electronic measuring instruments Transient sensitivity test for power supply
GB 6833.5--87* Electronic measuring instruments Electromagnetic compatibility test specification for electronic measuring instruments Radiation sensitivity test
GB 6833.6--87* Electromagnetic compatibility test specification for electronic measuring instruments Conductivity sensitivity test
GB 6833.7--87* Electromagnetic compatibility test specification for electronic measuring instruments Magnetic field interference test in non-operating condition
GB 6833.8--87* Electromagnetic compatibility test specification for electronic measuring instruments GB 6833.8--87* Electromagnetic compatibility test specification for electronic measuring instruments Magnetic field interference test in working condition
GB 6833.9--87* Electromagnetic compatibility test specification for electronic measuring instruments Conducted interference test
GB 6833.10--87* Electromagnetic compatibility test specification for electrical measuring instruments Radiated interference test
GB 7343--87* Passive radio interference test 10kHZ~30MHZ 30MHZ passive radio interference filters and suppression elements suppression characteristics of the measurement method
GB 7349--87* high voltage overhead transmission lines, substations radio interference measurement method
GB 9254--88 information technology equipment radio interference limit values and measurement method
GB 9383-1995 sound and television broadcasting Receivers and related equipment conducted immunity limits and measurement methods
GB 13421--92 Limits and measurement methods for spurious transmitter power levels of radio transmitters
GB 13836--92* 30MH2~1GH sound and television signals cable distribution system equipment and components radiated interference characteristics of the permissible values and measurement methods
GB 13837-1997 Sound and television broadcasting receivers and related equipment radio interference characteristic limits and measurement methods
GB/T 13838-92 Sound and television broadcasting receivers and related equipment radiation immunity characteristics of permissible values and measurement methods
GB 13839-92 Sound and television broadcasting receivers and related equipment internal immunity Allowable values and measurement methods
GB 14023-92 Measurement methods and allowable values for radio interference characteristics of vehicles, motorized vessels and devices driven by spark-ignition engines
GB 15540-1995 Electromagnetic compatibility technical requirements and measurement methods for land-based mobile communication equipment
GB 15707-1995 Limits for radio interference from high-voltage AC overhead Radio nuisance characteristic limits and measurement methods
GB 15949-1995 Cable distribution system for sound and television signals equipment and components immunity characteristic limits and measurement methods
GB/T 16607-1996 Microwave ovens above 1GHz radiated interference measurement methods
B 16787-1997 G Methods and limits of radiation measurement for cable distribution systems for sound and television signals at 30MHz~1GHz
GB 16788-1997 Methods and limits of immunity measurement for cable distribution systems for sound and television signals at 30MHz~1GHz
System class
GB 6364--86 Electromagnetic environmental requirements for aeronautical radio-navigation stations
GB 6830--86 Allowable values for hazardous effects on telecommunication lines exposed to strong power lines
GB 7432--87* Indicators of immunity to radio broadcasting and communication interference for coaxial cable carrier communication systems
GB 7433--87* Indicators of immunity to radio broadcasting and communication interference for symmetrical cable carrier communication systems
GB 7434--87* Indicators of immunity to radio broadcasting and communication interference for overhead Indicators of immunity to radio broadcasting and communications interference for open-wire carrier communication systems
GB 7495...87 Protection distances between overhead power lines and AM radio broadcasting stations
GB 13613--92 Electromagnetic environmental requirements for medium- and long-range radionavigation stations over the sea
GB 13614--92 Short-wave radio direction-finding stations (stations) GB 13614-92 Electromagnetic environmental requirements for short-wave radio direction finding stations
GB 13615-92 Electromagnetic environmental protection requirements for earth stations
GB 13616-92 Electromagnetic environmental protection requirements for microwave relay stations
GB 13617-92 Electromagnetic environmental requirements for short-wave radio transceiver stations
GB 13618-92 Electromagnetic environmental protection requirements for airborne intelligence radar stations
GB 13618-92 Electromagnetic environmental protection requirements for airborne intelligence radar stations
GB 13618-92 Electromagnetic environmental protection requirements for sea Electromagnetic Environmental Protection Requirements
GB/T13620--92 Determination of Coordination Zone and Interference Calculation Methods between Satellite Communication Earth Station and Ground Microwave Station
EMC CertificationAlong with the 3C certification, more and more customers are noticing the importance of EMC, and now we would like to take the first batch of household electrical appliances listed in the product catalog of EMC certification (1. Air Conditioner, 2. Refrigerated Box, 3, Refrigerated freezer, 3. freezer, 4. washing machine, 5. rice cooker, 6. iron, 7. electric fan, 8. hair dryer) as an example, to introduce some relevant knowledge to help pass the EMC certification.
Household electrical appliances EMC certification of EMC standards
Household electrical appliances EMC certification of EMC standards are the following:
GB4343.2-1999 "electromagnetic compatibility of household electrical appliances, power tools, and similar appliances, the requirements of the second part of the impedance," the standard has been released on March 23, 1999, the first part of the standard, the second part of the standard, the second part of the standard, the first part of the standard is to be used in the EMC certification. The standard was issued on March 23, 1999, April 1, 2000 onwards.
GB 17625.1-1998 "low-voltage electrical and electronic equipment issued by the harmonic current limits (equipment per phase current ￡ 16A equipment)" The standard was issued on December 14, 1998, December 1, 1999 onwards. The standard is to encourage the use of, if not qualified will not be certified as the basis for the overall judgment.
Household electrical appliances EMC certification test items
Household electrical appliances EMC certification EMC test items include electromagnetic emissions (EMI) and electromagnetic immunity (EMS) in two areas:
(a), the electromagnetic emissions (EMI) test items There are:
①. Continuous interference voltage (150kHz~30MHz);
②. Interference power (30MHz~300MHz)
③. Harmonic current (2~40th harmonic)
(2), electromagnetic immunity (EMS) test items are:
①. Electrostatic discharge immunity;
②. Radiated electromagnetic field (80MHz~1000 MHz) immunity;
③. Electrical fast transient/pulse group immunity;
④. Surge (lightning strike) immunity;
⑤. Current injection (150kHz~230MHz) immunity;
⑥. Voltage drop and short-term interruption immunity
Application for certification required to provide information:
1. EMC certification application form
2. Stable quality of the product and batch production capacity of the supporting materials;
3. Quality manual of the applicant company;
4. Application for certification of the product's production process in duplicate;
5. Product specification;5.
5. product specifications;
6. product structure in duplicate;
7. product electrical schematic diagrams and printed circuit board diagrams;
8. product EMC key components list in duplicate (stamped);
9. need to be required when asked to provide other relevant information.
Certification of product series division rules:
In view of the high technical content of electromagnetic compatibility, affecting a number of factors, in principle, should be applied for certification by model. However, the derivative products and the main product compared to the changes in the main product, can be divided into the following rules product series, the same series of products to choose a representative model for certification. Enterprises applying for certification should be submitted to the same series of products contained in other product models, specifications and differences with the application for certification model. 1. by product type, different types of products can not be divided into the same series. 2. by product working principle, the product can not be divided into the same series. 2. According to the working principle of the product is divided into different working principles of the product can not be divided into the same series. 3. According to the key components affecting the electromagnetic compatibility of products, key components, printed circuit diagrams, electrical structure of different products can not be divided into the same series. 4. The same trademark, the same specifications and models of products produced by different origins can not be divided into the same series.
Household electrical appliances EMC certification of key components:
Included in the first batch of directory of household electrical appliances, the main EMC key components are as follows:
1. air conditioner: compressor, computer control boards (including inverters), anion generators, power filters
2. refrigerated boxes, Refrigerated freezer, freezer: compressor, computer control board (including frequency converter), power filter, mechanical thermostat
3. washing machine: program controller (including timer), computer control board, power filter, motor
4. rice cooker: thermostat, computer control board, electric hot plate
5. electric iron: electric heater, thermostat 6. electric fan: computer control board, motor
7. Hairdryer:motor, filter, speed regulator