I. Introductory remarks 1, para. 1: p2/p1 = 10 lg (p2/p1) u2/u1 = 20 lg (u2/u1) i2/i1 = 20 lg (i2/i1) pdbw = 10 lg pdbm = 10 lg (p/10-3) udbv = 20 lg udba = 20 lg (i/10-3) pdbw = pdbw + 30 udbmv = udbv + 60 udbv = udbv + 120-chapter ii fundamentals 1, basic conceptual electromagnetic compatibility: equipment or system works normally in its electromagnetic environment and does not constitute an incurable electromagnetic harassment of anything in that environment. Electromagnetic harassment: may result in electromagnetic phenomena in which devices, equipment or systems can be reduced or have a detrimental effect on living, non-living substances. Electromagnetic interference: caused by electromagnetic harassment
2. Reduced performance of equipment, systems or transmission channels. Electromagnetic sensitivity: in cases of electromagnetic harassment, a device, device or system cannot avoid a reduced performance. Electromagnetic interference is three elements: source of harassment-coupling-sensitive module 3, general classification of electromagnetic harassment: natural and artificial harassment, sources of human harassment: radio communication equipment, industrial scientific medical equipment, electricity system, ignition system, electrical appliances and electrical lighting for domestic appliances, information technology equipment, electrostatic discharges, general principles of circuits: any current must be returned to its origin, and the current always follows the path of minimal resistance. Electromagnetic harassment transmission methods: conductivity coupling, magnetic field coupling, electric field coupling, radiation coupling. (1) guided coupling: two circuits share a single circuit, one of which has an out-of-date harassing current, and the harassing voltage generated on a public circuit affects the other, creating a transfer coupling or public resistance to coupling. I'm sorry
3. Measures taken by the public to counter coupling, electricity to resist coupling) to reduce the impact of conductive coupling: minimize the public part of the source circuit and introduce filtering measures (2) magnetic field coupling (electrical): the source of the harassment magnetic field has a magnetic interface (magnetic connection) with the interrupted circuit, thus insulating electric activity and spreading harassment in the interrupted circuit. The impact on the surrounding circuits when the source of the harassment is low voltage and large currents is mainly reflected in magnetic co-disruption. Measures taken to reduce the impact of the coupling of magnetic fields: reduction of the frequency of harassing electrical currents, reduction of the sense of interaction between circuits, reduction of the load resistance of jamming circuits (3) field coupling (electricity): the harassing voltage of circuit conductors is generated by a condensing of each other's circuit conductors with their proximity. When the source of the harassment was high voltage and small currents, his influence on the surrounding conductor, the circuit, was mainly manifested in the interference of the electrical complex. Measures taken to reduce the impact of power plant coupling
Measures: reduction of harassment voltage, reduction of the frequency of harassment voltage, reduction of the co-connection between the sources and loads of interference in circuits, reduction of the coupling capacity between circuits, appropriate increase of the distance between circuits and shielding measures to reduce the condensed capacity. (4) radiation coupling: electromagnetic harassment spreads in space by electromagnetic waves, connecting to interference with electrical circuits. Measures taken to reduce the effects of radiation coupling: reducing the intensity and frequency of the sources of harassment, avoiding the formation of antenna structures and the use of self-shield structures, connecting the antennas to the two extremes, introducing filtering measures such as co-ming filtering, using shielding measures - chapter iii blocking 1 and shielding categories: self-shield, electric shielding (static field and exchange field), magnetic field shielding (several magnetic field and transversal magnetic field), electromagnetic field shielding (high-frequency radiomagnetic field shielding, both electrical and magnetic field). The purpose of the shield: to limit the internal radiation generated beyond a given area, and to prevent external activity
5. Radiation enters an area. 3 self-shield (1) definition: self-shield means a method that does not increase external shielding and relies only on rational circuit design and structural set-up to achieve shielding on a largely cost-neutral basis. (2) examples: includes axle cable transmission signal, double winch transmission signal (3) field self-shield requirement: direct and negative charge encircling and distribution offsets each other. The magnetic field self-shield requires that the returning current be surrounded by the outgoing current and that the outgoing and returning current be of equal value. 4. Electrical floor shielding: purpose: to eliminate or suppress electrostatic fields or conversion fields from electrical couplings that interfere with circuits. Radio field shielding: to achieve static field shielding, two conditions 1 need to be met for a complete shield 2 to be well connected (1) the static field shielding principle: an empty cavity conductor is placed in a static field, the charge is distributed only to the surface, there is no electrical field in the cavity, the isolated external static field; the electric body is inside the cavity, the surface of the cavity
6. There will be no external electrical field for the sensory equivalent charge and for the aerial conductor. Conditions: full shielding, good grounding. (2) for the purpose of obtaining a good electric field shield, measures should be taken to make the shield as close as possible to the fully closed protected circuit as possible. The shielding effect is best served by openings or cracks that affect the effect of the shield. The shield is well connected and applies a good conductor in close proximity to the protected circuit. The shield is not required to satisfy mechanical strength. The magnetic field shield (1) aims at eliminating or inhibiting the constant magnetic field or the membrane field from the interference with the circuit. (2) the principle is that the magnetic field in the area surrounded by the shield can be significantly reduced by partitioning, using the low magnetic resistance properties of high-conducted magnetic material. (3) measures to improve the magnetic field shielding of magnetic materials: use of high magnetic conductivity material (polymers) and increase shield thickness to reduce magnetic resistance to shielding
7. The structural design of the proposed shield, which avoids the increase in shielding magnetic resistance, such as through openings, should allow the gap or strip vents to be placed in the direction of the magnetic field in order to reduce magnetic resistance. The shielding of the strong magnetic field can be implemented with a double shielding effect (4) measures to improve the shielding of the conductive material: use of a good conductor design to avoid openings, cracks, etc., affecting the flow of the vortex, should reduce the maximum size of the hole. 6 electromagnetic field block (1) definition: use of shielding to prevent electromagnetic waves from spreading in space. (2) when the electromagnetic wave passes through the shield, it results in reflective decay and absorption decay. (3) measures to be taken to obtain a good electromagnetic shield effect: use of a good conductor allows the shield to contain the electromagnetic field with a certain thickness, typically greater than ten times the depth of penetration to avoid a decrease in the shield's effect due to openings, cracks, etc., and the size of the hole response
8. 1/207 electromagnetic wavelengths less than the maximum frequency, shielding effect (1) against the electric field the effect of a gap, when the gap is narrow and deep, the magnetic field leaks small, and vice versa, the length of the large (1) gap should be kept below 1/20 electromagnetic wavelength, as far as possible. (2) the cut-off frequency of the metal wave pipe fc relates only to the size of the transect - chapter iv technical indicators for filter 1 and filters: insertion of depletion, frequency properties, resistance properties, rated voltage, rated currents, outer dimensions, working environment, reliability, etc. Insert loss formula 3, classified by frequency: high, low, transit, barrier. 4. Reflex filters (no-lost filters) working principles: to create a high degree of resistance to discontinuity on the path of transmission of electromagnetic signals, resulting in the reflection of most electromagnetic energy back to the source
9. Sometimes there is a resonance, which can be followed to form a barrier filter absorption filter (defacing filter) working method: the use of spoiled filtering elements to drain the energy of a disturbing signal into the filter for the purpose of inhibiting interference. Emi filters often work in a situation of resistance to mismatches and must consider their mismatch characteristics in order to ensure that there are better filters in the whole range (2) emi filters used to suppress electromagnetic harassment and that the characteristics of the source of harassment are understood so that they can be used properly and inappropriately, which may result in concussion, malformation, etc. (3) emi filters are primarily used to suppress high frequency electromagnetic or transient harassment, and they use a sense of electron, and the parasitic parameters of the element have a greater impact on filter performance and must be strictly controlled. (4) when emi filters are used on power lines
10/ in its electrical sense, the element is subject to greater voltage and currents and must be assured of sufficient resistance and capacity, as well as to prevent saturation of the electrons, emi filters ' basic circuit structure, and emi filter resistance matching principles to improve the effect of filtering in case of incompatibility, using different structures depending on the circumstances. The general principle is that the source, the load of low resistance is compatible with the wired sense, and the resistance is highly compatible with the combined capacity. The mechanism is to block the transmission of harassment signals when the source, load resistance, is low; when the source, load resistance is low, the connection is less effective, and the use of the connective capacity can provide a low resistance traffic route to the harassment signal, thereby inhibiting interference; when the source, load resistance is uncertain, it is often seen as high resistance and filtering with and connected capacity. The power line filter, the serial sense of the filter and the combined capacity selection are limited. Serial
11, esp meets u-permissive maximum power pressure reduction allowed for the equipment and an electrical condensing capacity should meet the maximum leak 9 allowed for the equipment by igor, the installation of the power line filter (1) installation position of the filter: filters should be installed as far as possible at the equipment entry and exit points, untreated power lines should not go too long inside the machine in order to prevent radiation, preferably using an interpolated filter, which should be isolated from the input and output lead lines on both sides of the container (2) the input output line of the filter should be separated from the line of the filter and should not be attached to the line of the filter (3): the filter should not use a long lead line to connect to the site, but should maintain a large conductive exposure of the filter site to the outside shell in order to ensure that it is well connected and that the outside shell must be connected to the ground 10, the non-ideal characteristics of the element - chapter 5 the input output line of the filter should be separated from the area of the filter and should not be tied to the line of the optimal location 0, and any electrical flow:
Inflows do not generate voltage relief and can serve as reference points for signal levels in circuits. 2. Purpose of the site: to establish low resistance roads to the earth, to make lightning strikes, leaks into the land without affecting equipment or endangering the safety of the person, to establish low resistance roads to the outer casings and nearby metal conductors, to establish public points or parallels, to shield areas, to connect filters, to print signal circuits on circuit boards, to receive ground level to provide a signal back to the route, and to provide a return route to the shell of a vehicle aircraft that is not a vital circuit connector. 3. Safety of location (connecting the exhums of equipment or systems to the ground with a low resistance conductor to ensure the safety of persons or equipment)
13 where the frequency is below 1 mhz, a single-point approach may be used. When the frequency is higher than 10 mhz, a multi-point approach should be used. When the frequency is 1-10 mhz, if the length of the line is less than 20, a single-point approach may be used, otherwise a multi-point approach should be adopted. - chapter vi impediments of transient harassment,1 inhibitions of transient harassment of switches (1) treatment of sensory load a, reverse at both ends of the load and uniode. Using the positive conductivity of the diodes, the load pressure was applied to the tube pressure down in the diodes, eliminating the charge of the load sensor's own distribution of the caps during the opening of the concern and avoiding the resonance. The instantaneous voltage is lowest and the current decay is slow. B. Reverse and connect to diodes and collude with electrical resistance. Resisting r in a series of diode circuits has reduced the time constant for load current decay, thus accelerating current decay, but the transient voltage during switches has also increased. So the chain resists r
14. Be moderate. C. Capable at both ends of the load. After the combined power c, the load of both ends increased, thus affecting the entire transient process, significantly reducing the amount of transient voltage, and the chain of circuits was designed to deplete power and reduce the concussion rapidly to zero after several cycles. D, at both ends of the load and connected electrical resistance. Consuming electromagnetic reservoir energy in loads through combined electrical resistance r inhibits transient voltage. Simple, but normal work has additional energy losses. E, with a pair of condensed converse pressure tubes. Since the voltage test value of the smoothing tube is greater than the peak of the voltage, the rated current is greater than the maximum load current, when the system is working normally, the smoothing tube is unconducted, and the transient process is shortened by the fact that the sensory load sensor's transient voltage exceeds the shock of the voltage tube, and the load pressure is applied to the steady voltage of the voltage tube, thereby limiting the rapid release of energy in the load. F, on load
15, both ends, and co-pressure for sensitization resistance. Pressure-sensitive electrical resistance is high in normal working conditions and, when exposed to high transient voltage, the equivalent is reduced to provide a continuous circuit for load currents when the contact is broken. (2) treatment of switch contact a, at both ends of the contact point and connecting to the barrier secondary. When the contact point is disconnected, the energy in the sensory load sustains the flow of electricity by holding the secondary route, limiting the rate and maximum value of electrocution voltage due to c. When the switch was closed, the capacitor was discharged through a switch, which limited discharge by the effect of resistance r. The value of the c should be greater than a given value, and the value of the r should be depreciated to take into account (direct flow communication) b, on the barrier and on the diode. When the switch is disconnected, the load current is charged to the cap c via the diode, limiting the lifting of the electrocution voltage and thus inhibiting hysteria. When the turn-off was closed, the energy of the electric field stored by the capacitor c was discharged via the resistance r-to- switch, which limited the discharge of the capacitor c. Straight
Flow) c, at both ends of the point of contact and with a steady pressure tube. The transient harassment is inhibited by limiting the increase in the electrical voltage of the transient contact through the forceplier of the steady pressure tube. (direct current) 2, wave suppressors (characterized, on-site) (1) function: used to associate with protected circuits or devices to limit and divert excess voltages beyond the capacity of the circuit or equipment to release wave energy. (2) commonly used devices: electric pyrotechnics, metal oxides sensitive electrical resistance, silicon transient absorption diodes (3), respective characteristics and application: hid tube current absorption capacity is high, but response speed is low, follow-up currents are high, dispersible, and voltage is low, applicable for crude first-level protection. Pressure-sensitive electrical resistance response is high and has a high absorption capacity, but the inherent capacity is large and unsuitable for high-frequency circuits. Silicon instantaneously absorbs a diode response with high speed and a large voltage slotting, but is less capable of carrying current loads and can be used for fine protection. Chapter 7 electromagnetic compatibility standard and measurement 1 , emc standard system basic launch standard basic standard base standard basic basic anti-intrusion standard general launch standard general criteria general anti-intrusion standard generic standard product category standard (cites b, commercial, light industry area) 2 , emc test content 1 hf emission measure (2) low-frequency emc disturbation measurement (3) anti-intrusion test 3 for products, china emc accreditation agency: china electronic magnetic compatibility certification board china compulsory certification: “ccc” certification
