Overview

With the development of electrical and electronic technology, household appliances have become increasingly popular and electronic, radio and television, postal communications and computer networks have become increasingly developed, and the electromagnetic environment has become increasingly complex and The deterioration of electromagnetic compatibility (EMC electromagnetic interference EMI and electromagnetic resistance EMS) of electrical and electronic products has also attracted increasing attention from manufacturers and manufacturers in various countries. The electromagnetic compatibility (EMC) of electronic and electrical products is a very important quality indicator. It is not only related to the working reliability and safety of the product itself, but also may affect the normal operation of other equipment and systems. Protection issues 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. Electromagnetic compatibility standards are the basic requirements for products to work properly in actual electromagnetic environments. The reason why it is called basic requirements means that even if the product meets the electromagnetic compatibility standards, interference problems may occur in actual use. Most national standards are based on those set by the International Electrotechnical Commission (IEC).

European Union regulations stipulate that from January 1, 1996, all electrical and electronic products must pass EMC certification and be affixed with the CE mark before they can be sold in the European Union market. This move has caused widespread impact in the world, and governments in various countries have taken measures to implement mandatory management of the EMC performance of electrical and electronic products. Internationally influential ones, such as the European Union's 2004/108/EC Directive (the EMC Directive) and the U.S. Code of Federal Regulations CFR 47/FCC Rules, all have clear requirements for electromagnetic compatibility certification. Standard

1: GB 4343-1995 "Measurement Methods and Allowable Values ??for Radio Interference Characteristics of Household and Similar Electric and Heating Appliances, Power Tools and Similar Appliances" This standard was released on August 25, 1995. Effective from December 1, 1996.

2: GB4343.2-1999 "Electromagnetic Compatibility Household Appliances, Power Tools and Similar Appliances Requirements Part 2 Immunity" This standard was released on March 23, 1999, April 2000 Effective from the 1st.

3: GB 17625.1-2003 "Limits of harmonic currents emitted by low-voltage electrical and electronic equipment (equipment with a current of ￡16A per phase)" This standard was released on February 9, 2003, It will be implemented on May 1, 2019. Replaces GB 17625.1-1998.

Content

In order for the product to have good electromagnetic compatibility, special consideration needs to be given to the design content related to electromagnetic compatibility. Electromagnetic compatibility design generally includes the following aspects. Ground wire design

Many electromagnetic interference problems are caused by the ground wire, because the ground wire potential is the reference potential for the entire circuit. If the ground wire is not designed properly, the ground wire potential will be unstable, which will cause the circuit to be unstable. Fault. The purpose of ground wire design is to ensure that the ground wire potential is as stable as possible to eliminate interference. Circuit board design

Whether the equipment produces electromagnetic interference emissions or is affected by external interference, or mutual interference occurs between circuits, the circuit board is the core of the problem. Therefore, designing the circuit board is crucial to ensuring the electromagnetic compatibility of the equipment. Sex has great meaning. The purpose of circuit board design is to reduce the electromagnetic radiation generated by the circuits on the circuit board and the sensitivity to external interference, and to reduce the mutual influence between circuits on the circuit board. Filtering design

For any device, filtering is one of the key technologies to solve electromagnetic interference. Because the wires in the equipment are very efficient receiving and radiating antennas, most of the radiated emissions generated by the equipment are realized through various wires, and external interference is often first received by the wires and then penetrated into the equipment. The purpose of filtering is to eliminate these interference signals on the wire and prevent interference signals in the circuit from being transmitted to the wire. With the help of wire radiation, it also prevents interference signals received by the wire from being transmitted into the circuit.

Banning and overlapping design

Banning is necessary for most devices. Especially as the operating frequency of circuits increases day by day, relying solely on circuit board design often cannot meet the requirements of electromagnetic compatibility standards. The prohibition design of the chassis is different from the traditional structural design in many ways. Generally, if the requirements for electromagnetic prohibition are not considered during the structural design, it will be difficult to add the prohibition effect to the chassis. Therefore, for the design of modern electronic products, prohibition issues must be considered from the beginning. Inspection items

The inspection items for electromagnetic emission (EMI) are:

The inspection items for electromagnetic emission (EMI) are:

①. Conduction (CE) ( 150kHz~30MHz);

②. Intermittent interference voltage (click sound) (150kHz, 500kHz, 1.4 MHz and 30MHz);

③. Interference power (30MHz~300MHz)

④. Harmonic current (2nd to 40th harmonic)

Flicker

The test items of electromagnetic immunity (EMS) are:

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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. Injection current (150kHz~230MHz) immunity;

⑥ . Voltage sag and short-term interruption immunity certification

1. For the electromagnetic compatibility certification application format, please refer to China Electromagnetic Compatibility Certification Center: Application Materials gt; gt;;

2 . A copy of the "Enterprise Legal Person Business License" or registration certificate of the enterprise applying for certification;

3. Proof of stable product quality and mass production capabilities;

4. Applicant enterprise Quality manual;

5. Production process overview of the product applying for certification in duplicate;

6. Product manual;

7. Product structure description in duplicate

8. Product electrical schematic and printed circuit board diagram;

9. List of key electromagnetic compatibility components of the product in duplicate (with official seal);

10. Other relevant information required when necessary

1. Sampling and determination rules for EMC certification

1. Randomly select 4 units from the 30 to 50 sampling units Samples, of which 3 samples will be used for inspection and 1 sample will be retained by the enterprise for future reference; if the number of samples is greater than 50, 50 samples can be randomly selected as the sampling samples.

2. The enterprise randomly selects one sample from the three samples used for inspection and sends it to the designated EMC laboratory for inspection. The inspection results are judged by being 2dB stricter than the limit specified in the certification implementation standard.

3. If the measurement result of a single sample meets the requirement of being 2dB stricter than the limit specified in the certification implementation standard, the sample is deemed to have passed the inspection.

4. If the measurement result of a single sample does not meet the requirements of the limit specified in the certification implementation standard, the sample inspection will be judged to be unqualified.

5. If the measurement result of a single sample meets the requirements of the limit value specified in the certification implementation standard, but does not meet the requirement of being 2dB stricter than the limit value specified in the certification implementation standard, the enterprise shall extract the other 2 The samples are sent to the testing agency for inspection. If the results of the two samples submitted for inspection both meet the requirements of the limit specified in the certification implementation standard, the sample is judged to be qualified, otherwise the sample is judged to be unqualified.

2. 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-Community country.

Failure to ply with these requirements:

●Will mean that those electrical or electronic 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 surprising imprisonment for a term not exceeding 3 months or a fine not exceeding amp; pound; 5,000 or both

3. Three important rules for EMC certification

1) Rule 1. EMC cost-effectiveness ratio relationship rule: The earlier EMC problems are considered and resolved, the smaller the cost and the better the effect. .

Carry out EMC design in the development stage of new products instead of waiting until the product fails the EMC test before making improvements. The cost can be greatly saved and the efficiency can be greatly improved. On the contrary, the efficiency will be greatly reduced and the cost will be greatly increased. Increase.

Experience tells us that it is the most time-saving and most cost-effective to carry out EMC design at the same time as functional design, and then pass EMC testing when the prototype and prototype are completed. On the contrary, EMC is not considered in the product development stage, and improvements are made only after the EMC is found to be unqualified after being put into production. Not only does it bring great technical difficulties, but rework will inevitably bring a great waste of cost and time, and even involves structural design and PCB design. Defects, inability to implement improvement measures, resulting in products not being put on the market.

2) Rule 2: The larger the high-frequency current loop area S, the more severe the EMI radiation.

The high-frequency signal current flows through the smallest path of the inductor. When the frequency is high, the wiring reactance is generally greater than the resistance. The wiring acts as an inductance to high-frequency signals, and the series inductance causes radiation. Electromagnetic radiation is mostly generated by high-frequency current loops on the EUT equipment under test. The worst case is an open-circuit antenna. The corresponding treatment method is to reduce or shorten the wiring, reduce the high-frequency current loop area, and try to eliminate any abnormal antennas required for normal operation, such as discontinuous wiring or overly long pins of components with antenna effects.

One of the most important tasks to reduce radiation harassment or improve radio frequency radiation anti-interference capability is to find ways to reduce the high-frequency current loop area S.

3) Rule 3: The higher the loop current frequency f, the more severe the EMI radiation caused. The electromagnetic radiation field strength increases in proportion to the square of the current frequency f.

The second most important way to reduce radiation harassment or improve the anti-interference ability of radio frequency radiation is to find ways to reduce the high-frequency current frequency f of the harassment source, that is, to reduce the frequency of the harassment electromagnetic wave.

4. National standards for EMC technology

National standards for electromagnetic compatibility technology, also known as (electromagnetic compatibility national standards, EMC national standards) basic standards

GB/ T 4365--1995 Electromagnetic compatibility terminology

GB/T 6113--1995 Radio interference and immunity measurement equipment specifications

GB 3907--83* Basic measurement methods for industrial radio interference

GB 4859--84* Basic measurement method for interference immunity of electrical equipment

GB/T 15658--1995 General standard for measurement method of urban radio noise

GB 8702--88 Provisions for electromagnetic radiation protection

GB/T 13926.1--92 General electromagnetic compatibility of industrial process measurement and control devices

GB/T 13926.2- -92 Electromagnetic compatibility electrostatic discharge requirements for industrial process measurement and control devices

GB/T 13926.3--92 Electromagnetic compatibility radiated electromagnetic field requirements for industrial process measurement and control devices

GB /T 13926.4--92 Electrical fast transient burst requirements for electromagnetic compatibility of industrial process measurement and control devices

GB/T 14431--93 Signal/interference protection ratio and minimum available field requirements for radio services Strong product category

GB 4343--1995 Measurement methods and allowable values ??of radio interference characteristics of household and similar electric and heating appliances, power tools and similar electrical appliances

GB 4824--1996 Industry , Measurement methods and limits for electromagnetic disturbance characteristics of scientific and medical (ISM) radio frequency equipment

GB 6833.1--86* General principles of electromagnetic compatibility test specifications for electronic measuring instruments

GB 6833.2- -87* Specification for Electromagnetic Compatibility Test of Electronic Measuring Instruments - Magnetic Field Sensitivity Test

GB 6833.3--87* Specification for Electromagnetic Compatibility Test of Electronic Measuring Instruments - Electrostatic Discharge Sensitivity Test

GB 6833.4 --87* Specification for electromagnetic compatibility test of electronic measuring instruments, power supply transient sensitivity test

GB 6833.5--87* Specification for electromagnetic compatibility test of electronic measuring instruments, radiation sensitivity test

GB 6833.6--87* Specification for electromagnetic compatibility testing of electronic measuring instruments Conducted sensitivity test

GB 6833.7--87* Specification for electromagnetic compatibility testing of electronic measuring instruments Non-working magnetic field interference test

GB 6833.8--87* Specification for Electromagnetic Compatibility Test of Electronic Measuring Instruments Working State Magnetic Field Interference Test

GB 6833.9--87* Specification for Electromagnetic Compatibility Test of Electronic Measuring Instrument Conducted Interference Test

GB 6833.10--87* Specification for Electromagnetic Compatibility Test of Electrical Measuring Instruments Radiated Interference Test

GB 7343--87* 10kHZ~30MHZ Measurement Method for Suppression Characteristics of Passive Radio Interference Filters and Suppression Components

GB 7349--87* Measurement methods of radio interference from high-voltage overhead transmission lines and substations

GB 9254--88 Radio interference limit values ??and measurement methods for information technology equipment

GB 9383--1995 Conducted immunity limits and measurement methods for sound and television broadcast receivers and related equipment

GB 13421--92 Limits for spurious emission power levels of radio transmitters and measurement methods

GB 13836--92* Cable distribution system for sound and television signals 30MH2~1GH

Allowable values ??and measurement methods for radiation interference characteristics of equipment and components

GB 13837--1997 Limits and measurement methods for radio interference characteristics of sound and television broadcast receivers and related equipment

GB/T 13838--92 Allowable values ??and measurement methods for radiation immunity characteristics of sound and television broadcast receivers and related equipment

GB 13839--92 Allowable values ??for internal immunity of sound and television broadcast receivers and related equipment and measurement methods

GB 14023--92 Measurement methods and allowable values ??for radio interference characteristics of vehicles, motor ships and devices driven by spark ignition engines

GB 15540--1995 Land Technical requirements and measurement methods for electromagnetic compatibility of mobile communication equipment

GB 15707--1995 High-voltage AC overhead power transmission radio interference limits

GB/T15708--1995 AC electrified railway electric locomotive operation Measurement method of radio radiation interference produced

GB/T15709--1995 Measurement method of radio radiation interference of AC electrified railway contact network

GB 15734--1995 Radio disturbance characteristics of electronic dimming equipment Limits and measurement methods

GB 15949--1995 Immunity characteristics of cable distribution system equipment and components for sound and television signals Limits and measurement methods

GB/T 16607-- 1996 Measurement method of radiation interference of microwave oven above 1GHz

B 16787--1997 G Measurement method and limits of radiation of cable distribution system for sound and television signals from 30MHz to 1GHz

GB 16788- -1997 30MHz~1GHz sound and television signal cable distribution system immunity measurement methods and limit system categories

GB 6364--86 Electromagnetic environment requirements for aeronautical radio navigation stations

GB 6830--86 Allowable value for telecommunications lines subject to dangerous effects of strong current lines

GB 7432--87* Indicators for resistance of coaxial cable carrier communication systems to radio broadcast and communication interference

GB 7433--87* Indicators for symmetrical cable carrier communication systems against radio broadcast and communication interference

GB 7434--87* Indicators for overhead open wire carrier communication systems against radio broadcast and communication interference

GB 7495…87 Protection distance between overhead power lines and AM broadcast radio stations

GB 13613--92 Requirements for electromagnetic environment of remote radio navigation stations in the sea

GB 13614-- 92 Electromagnetic environment requirements for shortwave radio direction finding stations (stations)

GB 13615--92 Electromagnetic environment protection requirements for earth stations

GB 13616--92 Electromagnetic environment protection requirements for microwave relay stations

GB 13617--92 Electromagnetic environment requirements for shortwave radio receiving stations (stations)

GB 13618--92 Electromagnetic environment protection requirements for air intelligence radar stations

GB /T13620--92 Determination of coordination area and interference calculation method between satellite communication earth station and ground microwave station EMC certification

With the 3C certification, more and more customers are paying attention to the importance of EMC. We would like to introduce the first batch of household appliances products listed in the EMC certified product catalog (1. Air conditioners, 2. Refrigerators, refrigeration-freezers, 3. Freezers, 4. Washing machines, 5. Rice cookers, 6. Electric irons, 7. Electric fan, 8. Hair dryer) are taken as examples to introduce some relevant knowledge to help pass EMC certification.

The EMC standards adopted for the EMC certification of household appliances

The EMC standards adopted for the EMC certification of household appliances are as follows:

GB4343.2-1999 "Electromagnetic Compatibility" Requirements for Household Appliances, Power Tools and Similar Appliances Part 2: Immunity" This standard was released on March 23, 1999 and came into effect on April 1, 2000.

GB 17625.1-1998 "Limits of harmonic currents emitted by low-voltage electrical and electronic equipment (equipment with a current of ￡16A per phase)" This standard was released on December 14, 1998. It will be implemented from January 1st. This standard is encouraged to be adopted. Failure to meet the standards will not be used as the basis for the overall judgment of certification.

Inspection items for EMC certification of household appliances

The EMC inspection items for EMC certification of household appliances include electromagnetic emission (EMI) and electromagnetic immunity (EMS). :

(1) The test items for electromagnetic emission (EMI) are:

①. Continuous interference voltage (150kHz~30MHz);

②.Interference Power (30MHz~300MHz)

③. Harmonic current (2nd to 40th harmonic)

(2) The test items of electromagnetic immunity (EMS) 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. Injection current (150kHz~230MHz) immunity;

⑥. Voltage sag and short-term interruption immunity

Documentary information required to apply for certification:

1. Electromagnetic compatibility certification application form

2. Proof of stable product quality and mass production capabilities;

3. Quality manual of the applicant company;

4. Duplicate overview of the production process of the product applying for certification;

5. Product manual;

6. Product structure description in duplicate;

7. Product electrical schematic and printed circuit board diagram;

8. List of key components for electromagnetic compatibility of the product in duplicate (with official seal);

9. Other relevant information required when necessary.

Rules for classifying certified product series:

In view of the high technical content of electromagnetic compatibility and the many influencing factors, in principle, certification should be applied for by model. However, if the derivative product has little change compared with the main product, the product series can be divided according to the following rules, and a representative model of the same series of products can be selected for certification. When applying for certification, an enterprise should submit the models and specifications of other products included in the same series of products and the differences between the models applied for certification. 1. Divide by product type. Products of different types cannot be classified in the same series. 2. Divide according to the working principle of the product. Products with different working principles cannot be divided into the same series. 3. According to the key parts that affect the electromagnetic compatibility of the product, products with different key parts, printed circuit diagrams, and electrical structures cannot be classified in the same series. 4. Products with the same trademark and the same specifications and models produced by different origins cannot be classified into the same series.

Key EMC certification components for household appliances:

The main EMC key components for household appliances listed in the first batch of catalogs are as follows:

1. Air conditioner Refrigerator: compressor, computer control panel (including frequency converter), negative ion generator, power filter

2. Refrigerator, refrigerator-freezer, freezer: compressor, computer control panel (including frequency converter) ), power filter, mechanical thermostat

3. Washing machine: program controller (including timer), computer control panel, power filter, motor

4. Rice Pot: thermostat, computer control panel, electric hot plate

5. Electric iron: electric heating tube, thermostat 6. Electric fan: computer control panel, motor

7. Electricity Hair dryer: motor, filter, speed regulator