Electromagnetism compatibility (EMC) it is to show equipment or system accord with a requirement to move to be opposite in its electromagnetism environment the ability that the electromagnetism with any equipment intolerable generation in its environment disturbs. Accordingly, EMC includes the requirement of two respects: It is the electromagnetism that in showing equipment is running a course normally, arises to be in an environment on one hand interference cannot exceed certain bounds to be worth; It is to point to appliance to disturb the immunity to interference that has fixed rate to be in the electromagnetism that exists in the environment on the other hand, namely electromagnetism sensitivity.

 

Alleged electromagnetism interference is to point to any electromagnetism phenomena that can make equipment or systematic performance demote. And alleged electromagnetism interference is to show the function of the equipment that be disturbed because of electromagnetism and causes or system drops.

 

EMC includes EMI (electromagnetism is disturbed) reach EMS (electromagnetism is able to bear or endure suffer a gender) two parts, alleged EMI electromagnetism is disturbed, carrying out for machine itself therefore the electromagnetism noise that goes against other system should be produced in the process that has a function; And EMS shows the machine is being carried out therefore should not suffer in the process that has a function all round the ability that electromagnetism environment affects.

 

The basic idea with 1. compatible electromagnetism, type and test standard

 

1.1 basic ideas

 

Electromagnetism compatibility checks EMC, it is to show equipment or system accord with a requirement to move to be opposite in its electromagnetism environment the ability that the electromagnetism with any equipment intolerable generation in its environment disturbs. Since maxwell build electromagnetism theory, He Zhi to discover electromagnetic wave comes more than 100 years up to now, electromagnetism can get be usinged adequately. Develop in science especially today, the domain such as remote control of broadcast, TV, communication, navigation, radar, telemetering and computer got rapid development, created enormous corporeal wealth to the mankind, especially the volatile development of technology of information, network, make the dialog of the world is apart from pull close. EMC test includes to check method, measuring instrument implement with test site, test method is a basis with of all kinds standard, measure an instrument to be a foundation with frequency domain, test site is the precondition that undertakes EMC checks, also be the main factor that measures EMC job level. EMC detects the effect that suffers place is very big, blast off with electromagnetism radiate especially, radiation receives the test with radiation susceptibility most strict to the requirement of field.

 

1.2 electromagnetism are compatible type

 

The lab cardinal principle that checks as EMC has two sort model:

 

One kind is course EMC authority the orgnaization is authorized with quality system attestation and the omnibus design that possesses legal test qualification and test lab, or say to detect center.

 

Another kind of type is the builds according to the real need of this unit and funds circumstance EMC lab that has fair test function. Basically apply to allow test and EMC to evaluate beforehand, before undertaking EMC attestation finally to make the product is in namely, have the medium that check oneself and evaluates.

 

 

1.3 tests standard

 

International Organization for Standardization has been mixed with the relevant specification that making EMC standard. Although the our country getaway in this respect is later, but development is very rapid. As the development of market economy, our country should participate in the competition of world technology mart, the electronic product of imports and exports must examine through EMC. Our country is legislative already 1998 import electronic product and communication terminal product compulsively to apply EMC detects to 6 kinds.

 

In the meantime, home also is in authorized and check and accept formal EMC attestation orgnaization and lab. The EMC of the product detects is implementation electromagnetism is compatible indispensable technical measure, carry out electromagnetism compulsively compatible standard, it is to assure product quality and the precondition that enhance market competition ability.

 

2. electromagnetism is compatible the method of the test

 

2.1 electrostatic immunity to interference detect

 

Electrostatic cent is osculatory discharge and air discharge, electrostatic it is accumulated high pressure, meet when the metallic crust of equipment of bring into contact with spark, can affect the regular job of electronic equipment, the likelihood causes equipment trouble or restart, better in security demand circumstance this is unallowed. Electrostatic meeting affects indication result, the likelihood appears show twinkle or Hei Bing, the influence shows normally and operate.

 

2.2 report are fast twinkling changes pulse group immunity to interference detects

 

Report is fast twinkling changes pulse group be a series of twinkling of high frequency high pressure changes pulse brings to bear on to go up in equipment, observe whether equipment is affected by its. Defend the method with group of main pulse is “ dredge ” and “ block ” up, close the effect of magnetism annulus is good smash magnetism ring at be opposite, in also can joining magnetism annulus board rank, secure in printed board, such making that equipment is more reliable. To line of power supply cord, line, communication two end increase magnetism annulus, can be opposite group of pulse interference undertake defending.

 

Surge of 2.3 be struck by lightning detects

 

Surge of be struck by lightning basically includes two fields, one is power source prevents thunder, one is signal prevents thunder. Power source prevents thunder basically is in the light of systematic level character, systematic level design should prevent thunder design according to 3 class, total power supply enters end to install power source to prevent thunder, can undertake to systematic power source one class defends, after power source prevents thunder through power source, enter segregation transformer, it is better to keep apart transformer to be able to disturb signal to undertake to electromagnetism defend, restrain its the influence to the system. Signal prevents the signal access that thunder is pair of systems to undertake defending, what basically involve is board course design, the parts of an apparatus that prevent thunder increases in board course design, be like gas discharge tube, increase TVS release return, carry release of resistor of form a complete set and TVS, gas discharge tube when having big electricity, circuit of the class after be opposite rises to protect action. After that signal undertakes photoelectricity is kept apart, reentrance system, the system can collect the signal that stabilizes to, make the system parses judgement normally, issue a statement normally, work normally. Design wider signal range namely on the other hand, when signal fluctuates normally, the system works normally.

 

The immunity to interference that induction of field of 2.4 radio frequency conducts detects

 

Shoot feeling experiment to may be opposite indication signal, collect drive to wait cause an effect, likelihood distinguish twinkles or Hei Bing, affect equipment operation, the likelihood makes collect drive the job is unusual, collect the signal that is less than need, cannot drive spot equipment. Radio frequency experiment is frequency of 0.15k ～ 80M undertake disturbing to line, power source inside limits, 3 class intensity is 10V/m. Shoot feeling defended principle is the screen power source, line has been done, screen layer is good ground connection, choose appropriate frequency to have filter wave, interference filter is removed.

 

2.5 radiate blast off detect, immunity to interference of radiate of radio frequency field detects

 

Should check basically be test system to fight radio frequency signal and integral screen function, want a system to had made good screen only, ground connection of systematic ground wire is good, the system can be passed detect. Pass relevant electromagnetism compatible test, the product can be pushed to the market, undertake trying movinged, to trying the question that in moving, appears, have pool, with the improvement of equipment product.

 

The control method of 3. electromagnetism compatibility

 

EMC technology adopted the policy that program of active precaution, whole and “ antagonism ” and “ dredge ” tie on the strategy that controls interference. The mankind is in conquer nature in all sorts of disastrous harms, sum up a series of strategy such as the precaution that go out and cure, antagonism and dredge, extremely effective thinking method is likewise in controlling electromagnetism to endanger.

 

Use well-known inhibition to disturb the technology of transmission, also can adopt evasive manage with the technical divisions of dredge, sometimes these are evasive with dredge technology simple and clever, can replace the hardware measure with quality cost cost is high and larger volume, get the result of get twice the result with half the effort. On the opportunity that solves electromagnetism to disturb a problem, development later period reveals an incompatible problem and should adopt by equipment rescue the passivity that repairs measure to control a method,

 

Change is become in equipment design initiative phase is begun forecast analysis and design, examine beforehand computation, comprehensive program implements detailed rules and measure, accomplish a nip in the bud. EMC design and dependability design, the design of basic function structure that defends design of gender, maintainability and product undertakes at the same time, collateral begin. EMC control technology is one of compositive content of contemporary and collateral project. EMC control strategy and control technology program can divide it is a few kinds as follows:

 

(1) transmission passageway restrains: Specific means has filter wave, screen, build receive, ground connection, wiring.

 

(2) the space is detached: Direction of vector of spot position control, naturally form segregation, azimuthal control, electric field is controlled.

 

(3) time space: Time is common when space of synchronism of pulse of criterion, radar, active time, passivity

 

Space.

 

(4) frequency management: Modulation of wave of frequency control, filter, frequency, number is transmitted, photoelectricity changeover.

 

(5) electric segregation: Transformer segregation, photoelectricity segregation, relay commutation of segregation, DC/DC

 

The design method of 4. electromagnetism compatibility

 

The basic principle that EMC designs and method, it is the requirement that raises to EMC according to products plan and relevant index above all, next, according to the relevant specification of EMC and standard, the EMC index that designs a product the requirement resolves class of yuan of parts of an apparatus, circuit class, module class and the index demand that produce grade, again according to various the functional requirement that wants implementation, chase what class divides administrative levels to undertake designing. The issue that EMC design should consider is very much, dan Conggen this getting on tell, the immunity to interference that how improves facility namely and prevent electromagnetism leak. The step that takes normally, on one hand equipment or systematic itself should choose the device with mutual the smallest interference, circuit and component, have reasonable position. Adopt ground connection, screen and filter wave technique namely again, restrain with segregation electromagnetism is annoyed. Have different design method and measure to different equipment or system.

 

(1) yuan the analysis of the choice of parts of an apparatus and circuit is EMC design foundation.

 

(2) the EMC design of power source system.

 

(3) the interference rejection design of ground connection system.

 

(4) printed circuit board EMC design. Additional, notable is when undertaking EMC is designed, scarcely can oversight is right of electrostatic discharge defend. What ESD defends is crucial, it is the generation that prevents electrostatic nucleus is mixed accumulate, cut off namely again the happening of ESD effect.