【 Weak current College 】 on audio and video quality of power supply and grounding problem---Power By 【 China power house network 】

Use the new digital electrical equipment must be dropped before the grounding of all kinds, coupling, shielding method.
Times change, our appliances are also changing, analog power supply, electronic circuits and power amplifier area is gradually giving way to digital conversion and logical design and other new areas. Lighting control field, this change has been completed. Although we have a lot of people noticed this progress, however, we use the original analog electronics, accompanied by AC power connection, grounding and audio-visual system connections, and so on, when we use the operation performance more stable new digital electrical products, related to these factors and how to change?
First, let's see, analog circuit element is used to zoom in and combine new electronic signal, analog audio front-stage amplifier and Mixer with EMF meter to directly change the input to the circuit components on the signal level. Potential include Rotary and sliding type two, time will produce noise. New digital circuit of control of the same type, but there is a little different, that is: they can change IC communication gain is based on the potential meter resistance from AC to DC conversion process produces digital binary value gradually changed. Noise in the conversion process to be filtered.
Some is used for mixing and gain controller to no longer use the potentiometer, now from optical magnetic perspective, they are coupled with digital encoder, the rotation of the wheel or wrench slip bits directly into digital pulses that binary digital, then we will have a lighting control system, audio and video mixer and similar circuit products, such as through a digital connection of portable or desktop PC system, although the performance better fiber light guide even more secure, but the road to balance road are typically popular, such as RS-232 type or RS-422-, radio systems co-exist and also use the control and signal Lin Road, but still use wire winding up, to geteven the road of electrical signals. These electrical cable part uses the digital signal or other patent signal.
Once we talk about the actual control that new digital electrical products handle audio and video signals, we found that these signals are all digital, using oscillators don't see phase transformations, amplitude variation of the AC sine wave, DC Locator, analog waveform signal. Now their moments of a square wave, pulse width co-ordination (PWM) or represents the full digital control of the encoded binary digit, audio and video signals, etc. Often on PC using audio, video discs and anyone familiar with this, because only the analog signal to the microphone or speakers are connected.
Even if you look at AC and DC power supply, we now can only find two use DC (input filter capacitors and voltage application logic or output connector); other circuits are control of one or two square wave. Ten thousand hertz frequency and within the PWN circuit in the power supply to meet within the cloth. On the contrary, the analog power supply in the power generation process only 50Hz-60Hz AC input to the rectifier, other places or you may find some pulsating 120Hz DC or "pure" level of direct current. Legacy linear power supply (analog or linear design) principles of the structure; the new switching power supply (SMPS), the difference is very big.
Power amplifier may be digital only after reform of an application. In General, its output will eventually be feedback to the analog sensors (also known as speakers), and analog signal appears on the amplifier you is another matter. The power amplifier, digital circuit in every aspect exceed the final output, and even use digital power amplifier and special filtering to eliminate high-frequency components (such as carrier). And then washed with filters help to build video-band signals for analog voltage and current.
In the simulation of electrical fields, we particularly like quite a reputation of a single point ofgrounding (SPG) systems and static ground grounding electrodes, typically have mysterious property 1, simply connect to the appliance. This application has been reserved at 250 products have a NEC corruption — grounding. From this premise for all ground grounding require fire, earthquake, power control, by using shielding grounding lightning can solve this problem, from electronics, and other electrode. Building electronic systems (security) electrical grounding conductor (EGC) system, including metal cable pipe, metal electrical cabinet and power supply lines on the famous Green line.
Now the situation is totally changed, because modern analog and digital appliances in use of earthing design, accept AC power system of power supply connect grounding green line method, ignoring all models of special connection. For example: our room-good appliances, these appliances are used in signal level cable plugged in, and use signal reference frame (SRG) to ensure the functionality with bandwidth, and common ground model of noise in the connected unit is attenuation. The following also explains a lot about the content of the SRG.
New digital appliance obviously different, and is not subject to the simulation of electrical problems plague us. But we have been discovered and digital appliances for new problems to be solved. We should pay attention to emerging important rules, especially for new digital appliances, these are generally used for the simulation of electrical appliances, for example: some electrical ground rules to do the important fixes. We will also see that there are some influential cable shield rule, unless he is blind, lightning and electronic protection requirements are to appear, and that is not understood, we use electronic hosted appliance even more important, particularly for digital appliances.
With this understanding, let's start exploring digital audio-visual equipment for this new area, and recommended that the AC power, ground and AV cable system.
Power quality and performance issues
In the application, the computer system displays numerical (1 or 0) of logic circuits and digital circuits of audio-visual appliances almost no difference, therefore, in the computer field successfully developed numerous information directly applicable to compressor operation of electrical equipment. (Don't forget this is a computer appliances as a starting point). When we study CBEMA curve, this can be proved.
CBEMA represents legacy frame-shaped computer manufacturers association. The curve is determined by the Association of power interface CBEMA as third (SC-3) development, can be used to determine the AC power quality and a variety of digital logic appliances.
X axis represents time and standard frequency 60Hz power cable to the United States every second running laps. The y axis represents a voltage of +/-parameters. Y axis parameters for a 100% equal to the nominal rms AC voltage. For example: 120 volt AC power at 100% of the line; when the voltage rise, the curve will rise along the y axis (for marked twice, three times, and other AC rated voltage increment until 100%). When the cable line voltage drops, the curve along the Y axis to 0 points, the power to disappear. Logarithm of X axis determines the tracked of sustainability, for example: If the AC power line down to 0 ° c, voltage up to one minute; and then a digital heart returns to 100% of the curve. Of course, this can be inferred that the voltage can be restored to 120V AC, i.e. 100% of the curve. If you cannot restore the curve that need to be restored to his last level status.
Transient-voltage or tilt phenomenon
The most frequent power quality problems called tilt. Tilt the case there are several different views, such as loss, dive, but according to the IEEE's the green power guide provides "tilt" is a term to widely accepted. The rated voltage exists in italic before or after the occurrence, inclination leads to effective because the voltage drop in a circle of obvious or several times.
Common case is when the application has high moment of beginning or into current system or hosted circuit. Such common carrier from block Panel, motors, AC and DC Power Rectifiers and commonly said, AC and DC power supply has a maximum input capacitor, through rectifier it plugs into a curve. With a large, empty capacitors, large charging current can be present in the first half of the circle, but in the subsequent half rings will gradually decrease until then we charge voltage of capacitor.
Transient phenomena of high pressure or expansion
As expected, the expansion is opposite with tilt. Expansion is also called Chung pressure, but the word is not correct, because the "surge" is more suitable for shorter duration, including instantaneous high voltage, the voltage produced as lightning. Expansion of the term is now officially included IEEE, expressed above happens on expansion of correct understanding, with rated voltage is present in expansion occurred before or after the results clearly effective voltage rise a ring or for several laps.
Common expansion often is to cancel the electronic system or high flow current 8t large load circuits. The host is determined by the Panel, motors, rectifiers and large ' not with a power-down control while connected to the AC and DC power.
The phenomenon of pulsed voltage
Common pulse phenomenon has many names, such as false signals, spikes, nicks, snail-like feelers, transitions, pulse, etc. Its characteristics are polar assisted circulation or band assisted circulation. It is this unique characteristics but makes the pulse groups appear, perhaps with one of the reasons for, maybe not with it. Pulse and AC power curve of a voltage or current either synchronous or asynchronous. Pulse will appear in the C8EMA curve to the left, and 8.33 Ms assisted circulation area, pulse will all remain in 10004 curve above or below, will be part of the reserve in the curve is above or below. This may have the decay of turbulence characteristics. Fast transition time and pulse 3 closely linked, but its interface in addition to the basic AG power system frequency ratio is not visible outside. All in all, pulse transition time is always there, in AC circuits with MS or microseconds. When the pulse source very close to measuring point, the transition time will speed up, this is because the time in high-frequency AC circuit is lossy transmission curves, tend to increase as the distance attenuation of the HF signal.
Turbulence phenomena of voltage decay
Pulse decay may and attenuation of vibrations current or voltage waveform, depending on how it is initially started, how to interfere in the AC power system wiring launch out. Note: the AC power system including reactor and is LC circuit, on the basis of frequency or harmonious related frequencies even will have resonance. Therefore, the turbulence in the circuit is very common. These shocks at frequency according to LC circuit involving cable system q value of different or other loss. In General, only a handful of very high frequency pulse attenuation repeat can be seen, because it AG power circuit of the index type is frequency in soon. Ultra-low frequency attenuation of vibrations frequency is extended slightly longer points through a longer cable path can spread out.
AC power line to see the decay of turbulence in CBEMA curve to the left and in 8.33 Ms assisted circulation disturbances can be seen in the region. But sometimes, it is not the case, the line will 8.33 milliseconds and shock wave in a wave of tail intersecting. Shock general movement in 100% voltage line above or below, but sometimes very DC offset arise, and walk up and down the line. There is a good example: AC power system attenuation turbulence is determined by the rows of the power factor capacitor open to "import" (sometimes "export"). These phenomena have energy, but also the post contains low-frequency content.These factors will enable interference leads to, and in the electronic recharge system access equipment and appliances before several miles miles distance attenuation without significantly after. Equipped with a switch of a bunch of power factor capacitor common circuit diagram. Here's the general rule is: capacitor bank from the shadow of child devices closer, the greater the potential of stem will, and vice versa.
Most power calibration capacitor banks installed on a three-phase noise circuit, used for electronics supply system itself, in the device's main feed unit within a system, or both locations. In both cases, the unwanted effects, it is easy to reach the building of the secondary feed unit and branch circuit system, and get connected electronic hosted equipment. What caused the attenuation of capacitor turbulence? when a discharge capacitor directly near the peak by pressure even when the AC cord can cause part of the askProblem. Another way to charge capacitor voltage in the curve is far below the capacitor voltage is connected to the AC line can produce.
In the first case, the capacitor from AC line for many current. Due to the high power circuit impedance of the capacitor will result in voltage temporarily plunge by phenomenon, through downstream load looks like without preparation of the voltage drop 01E second, capacitor to AC line added pressure. This pressure will cause the line conductors without voltage connection point from the capacitor to spurt of instantaneous two-way. Although this increase appears to be bidirectional instantaneous spurt, but it's actually increases the load to be. When used to connect three capacitors bank of mechanical contact no sync contacts, it will have another question, that is, leading to two capacitor to be connected, directly resulting in two related power system produces special on the conductor. Accompanying this interference was also common.
The two cases of either, including capacitors and AC line of LGproduct generates turbulence conditions until the capacitor charging become and line voltage frequency synchronization. As with line reactance load connected to the simple, due to impedance, capacitors generate tendentious power factor correction.
Communication disorders
Often you can see the AC line voltage waveform, and remove from the waveform of one, two obstacles exist simultaneously. Any local will produce this kind of disorder, and was ordered by the time the Congress has been from the start time. They are known as the communication barriers, is generally caused by instantaneous short-circuit, self controlled rectifier in one open and one closed AC line between is located in the middle. With SCR, i.e. the phase switch, easy to see the barriers along the X axis movements, they generally located GBEMA curve and assisted circulation area 8.33 Ms line left.
Several zero on the airwaves of cross
In the capacitor of attenuation turbulence, zero voltage curve and the phenomena of shock parts or harmonious voltage several intersections. If you impediments in deep shock and the edge of existence and zero voltage lines intersect also happens. In both cases, the result will produce more voltage zero cross, on any rely on zero-voltage 60Hz curves cross point of the timing or SCR rectifier appliances will have serious impact. Some SGR's lighting control system will be affected by such problems. If you rely on the voltage waveform calculation number table zero cross or timer 60Hz circuit each 180 degrees will be more than one voltage zero cross, the speed will be faster!
Harmonious voltage waveform distortion
Using nonlinear load, such as various rectifier power (linear and SMPS), the current in the relevant frequency from 120-Volt in the AC power cord to 60HZ. In General, all current are in the form of pulses; 90 ° to 270 degrees, to avoid running along a given voltage waveform linear flow. Common for SMPS input current wave shape. This wave includes a peak current, affected by circuit, there is a significant drop, through the AC power circuit impedance including wiring, power transformer impedance, oscillators of winding or other AG power of internal impedance. For consideration and the fun, the impedance can be used to temporarily AC power system for flexible power line equipment amounts. If the long branch circuit with extended use wire together, then it is a new discovery! in non-linear load and AC power supply, a power modulation device, such as wire voltage modulator, sometimes make the situation worse, because the usual power modem devices typically have many inner resistance, and internal resistance will directly increase the voltage waveform distortion problems. Common nonlinear load, such as with 120 volt AC connected SMPS will require fundamental frequency currents and harmonious current both reached the No. 19 (19HZx60HZ or 1, 140H2) o in most cases, the current from the odd harmonics (3, 5, 7, 9. ….), And from low to high order (particularly the third, fifth, seventh harmonics).
Once the nonlinear bearing (such as rectifiers) require from an AC power circuit for harmonious current, voltage drop, and road in the series through a variety of impedance. Thus, if the number of third-harmonic currents in the upper 10 Volt circuit in decline, this situation is considered from 10 Volt 180Hz mathematical increased to 120 Volt fin Hz fundamental voltage. From this phenomenon observed in voltage waveform appear peaks and valleys, or called a hump voltage, depending on how people are describing the artifact. And the amp Foundation wave current 60HZ frequency compared to the current path in 1A180Hz (third harmonic) inductor resistor (XL = 2fL) will make the voltage drop in the total of 3 times, which also applies to a higher level of harmonic current system, because the inductor resistor is increases along with the frequency and the proportion increases.
Note: harmony-distortion voltage waveform has a total area of no distortion sine wave has a total area of many, and its peak voltage is lower. This is linked to the linear power supply, problem than SMPS design more. Former lost fixed space, the more the more thermal running, because as a low pressure, when the output is connected to the linear power supply will make the appropriate response. And SMPS more available space, will be 90 degrees, — 270 degrees of the main energy storage capacitor simply use a higher peak charging current to compensate. There are enough distortion, two power supplies eventually lost fixed space but linear power supply always comes first, and a little more.
An important recommendation: If you want to not carry sine waveform of AC power conductors measured voltage or current, you can only use truly effective instrument. Common analog or digital current or V table is not real effective instrument, but a general measuring instrument (valid calibration equipment). In other words, it is full-wave rectification DC instrument is marked with a degree in pure sine wave on accurate to effective O.707 value. Harmonic distortion typical of a wave, the instrument reading out the lower region of the curve, the reading result is error 50% leftTo the right. In other words, in such instruments, the effective current 20A might be reading about the value of doing 10A. This will enable users to mistake: no serious load circuits. Voltage waveform on the same problem occurs, users will be mistaken: AC line voltage is too low, the need to improve, and, of course, including the voltage and current calculation, this situation also have made a mistake.
Common SMPS and linear power tilt effects on
Research CBEMA curve of another way is to confirm that the Centre axis and 8.33 Ms point area on the left below 100 per cent of the area, as the lack of high-quality energy reserves in the region. In common SMPS input, filter capacitors have occurred. In a well-designed SMPS units, this is a relatively large capacitors, from full wave bridge rectifiers, enter directly through the AC line. The capacitor has full power and almost reached the peak of the AC line voltage (169 volt DC, 120 volt AC wire), and can store large amounts of electrical energy (Q = CE), you can power through extraction, than in SMPS with logic voltage circuits better. Therefore, it is like a flywheel, once the engine start, the machine will always run. However, the poor quality of SMPS power or good at but excessive load of the power supply is likely to lack of storage energy, on the main input capacitor AC line voltage on, once we must decline to tilt the persistence of the charging current provided then. At the point in SMPS is described as: when used for SMPS full-wave rectifier output, the peak AC or less than the half rings of current voltage level. Because linear AC DC power supply for operation from-input-voltage transformer on the decline for all filter capacitor. Capacitor voltage are filled with a linear voltage regulator continued work on the charging voltage difference was not significant. People put this difference is called the "space". These two little contrast between design — hence the competition lasted down and SMPS became the winner.
Since Q = CE, so for the same size of capacitor, 120 volt AC line voltage peaks at 17 sites at the time of the effective amount of stored energy is higher than 25 volt AC auxiliary voltage transformer 40 peak store energy. Also, think about, in addition to 240 v AC input is able to do exercises, and 120 volt AC input cells same SMPS and can store much energy?, Neil, SMPS, capacitor also attached directly on the rectifier input! have a linear design, there is no difference between the two, because the auxiliary voltage step-down transformer will not change, only the base voltage becomes; therefore the result is the space not changed.
In analog power supply DC input and output ratio of SMPS. Linear voltage dip and SMPS contact little, comparing them to the same power output ratios and linear AC DC power to know-. Digital difference and output ratio compared to the same linear power supply, better performance, lower prices, and volume is smaller, lighter weight SMPS. Only when the linear power supply with the support of the commodity in short supply, compared to the more costly, size and weight are larger, in order to compete with them!
Most research on AC power (IBM, Bell, etc) has confirmed the AC line voltage tilt phenomenon, this has not surprising, but electronic, computer, consumer experience is as usual power quality issues. Although neglected as tilt phenomenon such AC line power supply problems, people think that SMPS digital appliances to better than analog electronics, but still have a little tilt phenomenon can cause performance problems.
Common SMPS and linear power supplies to the expansive effect
Expansion to the SMPS input, the result of predictable: it utmost knot full-wave rectifier full power, then to enter energy storage capacitor charging. In ordinary SMPS, this is quite a big number, so the effort is not as easy as it looks. Here contains an RLC continuous time, not only including capacitors, also includes the expansion of the entire upper cable systems of reactor and resistance. Therefore, it is very difficult to fill capacitors; instead, it is introduced into an existing, and have it stored for future use. If this can produce more than linear peak, high voltage capacitors does not simply in the next half-circle on the acceptance of any new charge until some SMPS insert loading after half-circle have capacitor voltage consumption to less than the AC line peak voltage following start only after receiving a new charge.
SMPS power transformer is high (typically tens of Hertz) switching circuits, involves close and alternating saturated equipment, its energy to independent input energy storage capacitor. Secondary pressure converter is a full-wave rectification for to a secondary energy storage capacitor in close connection load using voltage at a charge. By pulse width requirements of transformer (control their work cycles), we can in the capacitor charging level on the control.
Even if the primary input energy storage capacitor in through Terminal may have a large number of voltage changes, and eventually to transformer services auxiliary energy storage capacitor will be on a stable voltage G note/auxiliary energy at any time through the storage capacitor, the voltage is too high, the transformer will be ' by pulse broadband provides circuit temporary shut-off. This is in some parts of the SMPS set up automatic protection measures to avoid the line reaches the load and pressure, the effect is very good.
Use linear power supply, the expansion will enable input low voltage auxiliary converter main energy storage capacitor charging too much, and it's powered by linear voltage regulator circuit cannot withstand excessive voltage, so will the service load loss adjustment function, the result of the DC power supply output voltage is too much, not to disrupt or damage the connected load. In addition, the control circuitry itself will suffer. DC level arc circuit sometimes is the only protection that avoid these problems, but it is not — a good method, especially it does not automatically adjust to the EMI to trigger.
Other impact
Because almost all kinds of pulse and turbulence contains frequency components than recurrent tiltingOblique or expansion of the frequency is high, so they can be affected by the EMI effect resulting from the additional power supply.
Common problems are related to AC line extended electronic interference, including the provision of unwanted output, input (and attached to a higher level circuit)--power supply design. When it comes up to tens or a few kHz frequencies, and a few stray reactance also form important circuit between coupled, this is especially true. The power of General questions relating to the installation point, and the opposite, because current e-field is relatively high, circuit impedance and voltage is relatively low, so most issues involve scattering magnetic field and a wired device and PC scan point routes.
About EMI immunity problems, successful experience of SMPS is widely known as the circuit it is rich of EMI generator. In this way, SMPS must as far as EMl and electromagnetic compatibility point to good design, otherwise, it does not work, or if it is in use in electrical equipment interference, making it from his poisoning with anti-EMI's ideals by external effects, such as when connected to AC power line. In this case and common linear power supplies, common linear power supply itself is very quiet, usually not by EMI resistance points to design.
Now for example. Often: a circuit devices with linear power supply, but it also affected by the AC cord EMl issues, so the load may be cut off of a compatible power supply (UPS) on the load and impaired AC line. This change is to be able to solve the problem, but it is how to solve?
In fact, very simple. It was in the "victim" of the circuit to SMPS on AG wires and linear power supplies. But in addition to UPS, the UPS AC power supply and electric appliances of the real differences between SMPS is high power without rectifying the transformer output to load provides DC power rather than 60HZ. UPS battery and SMPS primary input energy storage capacitor similarities between the obvious and will not repeat them here.
Mitigation issues
★ Select AC power: electrical products to use appropriate AC power supply, this just means to plug into the wall of the recently isolated electrical plug, and avoid making the industry General error, that is, attempting to obtain special for a device or a dedicated AC power supply. Therefore be appropriate to the task of AC power from the AC power supply.
★ Upstream: the audience the best advice is an AC power source is the starting point, or upstream, closeto the building's electrical service (SEQ) more realistic. This is the dedicated SEQ feed device connected to the electrical equipment in the room, and in this room, it is through independent converters (IT) or another appropriate power supply equipment coupled to one or more of the Panel.
This design principle is very simple. Whether in buildings where use of AC power, no matter what the effects will be similarly SEQ building levels-level power distribution. For example: even if SEQ on transient-voltage (tilt), the building within the electrical plugs on discovery. However, if someone in the distribution system in a very far plug reverse gained power, so any impact feed unit or the selected Plug and SEQ something between Panel will affect the choice of auxiliary plug power quality. After strict figures known: power quality in SEQ is best, but after the allocation system is getting worse, but the building itself will also appear in the load.
★ Have low impedance power: all power have internal impedance, for example: it limits short-circuit current through electric River or converter Terminal. Internal impedance is inevitable, yet practical, unless it is because there is no account and get into trouble.
Common electrical load device power includes rectifier input. These input requires each semi-circle with non-sinusoidal peak current, so that the voltage through the power of internal resistance can significantly down and power efficient voltage waveform distortion of the compatibility, so that the resulting compatibility distortion voltage waveform will give ordinary electrical load equipment operation leads to numerous headaches.
Power circuit of harmonic is so strong that usually has access to telephone and electrical equipment signal level circuit, and leads to many problems. For example: AC power system simple voltage wave harmonics very serious because they can also cause related AC power line to raise broadband audio frequency to interfere with thesystem or in the vicinity of the signal cable. Another example: on a simple DC power supply AC — overrides of interference to 2KHZ 60HZ. In the less-frequency voltage waveform to mark to appear. Valid harmonic can scale up to dozens or even hundreds of kHz effects to other video or digital conversion process.
Harmonic voltage is reduced to a reasonable level after the guarantee: the selected internal AC power supply should have a low impedance. For common service switch (ST), that a correction has no problem, but it became a building electrical dry type converter or other types of power conditioner, and benefit from the power supply. Here is the recommended method, i.e. the establishment than loading the required capacity greater KVA AC power supply, its internal resistance in 2.5%--5% range can avoid many problems. Note: most of the voltage regulator and power UPS all may not be able to meet the requirements of the internal resistance, but sometimes it is very practical. This requires determined: the regulator or the ups must be within the output voltage feedback circuit, it can see the output voltage waveform, and the error correction signal feedback into the control circuits, which makes the output waveform distortion and RMS voltage level remains in the same control. In this case you can use the active way to compensate the internal high-impedance.
If the power regulator device does not have good output voltage waveform control, output voltage waveform distortion, the situation is not as simple as building power system direct power supply. Sometimes the problem will be very serious, so when the electronic load device and power conditioning unit are connected improperly, and construction powerWhen connected to the normal movement but may
Line. In commercial trade, this is regarded as an expensive lesson.
Electronic load of NEc connection modes
From a historical perspective, in and to the electronic load electric power supply of AC power branch circuit are connected, NEC does not require too flexible, generally only two methods: fixed ground (SG), and quarantine or insulated grounding (IG). Often supply of AC system can only use fixed ground method. (This means that the power converter neutral electrode adhesive received equipment grounding insulation system, the recent grounding of NEC Earth received 2,150 VAC AC system converter. See 250 – 5 and 250. 25 section). Although the device performance perspective, this is a good method, as in the common electrical equipment installation can reduce overhead shots, and other noise, but it was barred from the branch circuit. Product safety testing and listing service (such as UL) are very clear, that is, the detection of various electrical equipment and safety standards must be consistent with NEC03 (1996 Edition).
Ac systems and branch-circuit ground
Traditional two AC systems and branch circuit ground method (SG design) and (IG design) as shown, including branch circuit is in the noise and buzz condition used to support common electrical load installation equipment. 1996 NEC's new version before, only these two design patterns. Two grounding has a dual nature. First of all: the common 120 volts RMS branch circuits, hotline should be on the highest voltage is 170 volts potentials in the grounding. Second: as the grounding system of the General noise current in the presence of common-mode (CM) noise current appears in branch circuit of neutral or febrile conductor. This unequal current then add to the load (febrile or neutral conductor) AC power line into normal current.
The first case said: e-field location very high thermal resistance of conductor, distance, and any recent grounding of all relevant, such as installed in the power cord near the audio cable of the shield. The high e field maximum coupled AC power and grounding shield, this will put the drone and noise into the audio cable. This is ideal for high-impedance circuit is particularly important, because they are driven by voltage. Note: If the AC wiring on effective grounding voltage drop, from electronic field entered a nearby signal level conductor coupled disturbance may deteriorate. Because electronic field belongs to the near-field, it is proportional to the voltage, the turn along with the related expansion of the distance between the conductor and the rapid decline.
The second case said: from a mathematical viewpoint, converted to common mode (CM) noise reduction is the noise in the circuit for the desired supply current is attached, the interaction with circuit impedance, and will become a normal noise voltage, and to the AC voltage waveform. Then, load device must have an AC input power voltage across the entire noise-free audio frequency over and over, not only in 60HZ and 120HZ. This implies to seriously consider the rectification procedure after special design of the filter system, such as the use of extremely low series resistance leakage value electrolytic capacitor and the inductor with low leakage. For example: linear power supply will cross over into the noise voltage to the DC power output, and can affect the performance of the regulator circuit run. It can pass through it to or around the control circuitry, and enter into directly with electronic circuits connected terminal DC bus structure, when these are simulated performance with audio bandpass low level mixer or amplifier, it will become quite a headache. Note: when you use the generic SMPS, this won't be a big problem, because the conversion between the stage to the stage of transformer provides enough amount of attenuation, and noise removal to the circuit, such as the control circuitry.
New method
AC power system wiring and grounding of the new method is to use a 120 volt AC System Center-tapped for single-phase AC power, and the establishment of a branch circuit system, will soon be all insulators symmetrically connected to ground. Rated AC voltage ground must be original,for example, the original valid values for 120V, now only 60V valid values. The AC system and wiring and grounding requirements will in the first section 530 NEC raises shadow, depending on the camera and similar establishments, G; 60 Volt grounded individual branch system. Use fixed ground method (SG) new AC system grounding method shown in common wiring design; insulated isolated grounding method (IG) shown in the design. NEC internal to 60 VAC received power system operation part 530-70, generally described as: use branch current 120 volts, single-phase, three lines, and with the 60 volts of two non-grounding insulator and a grounding insulator system should be up to A month-V product or other inductive electrical equipment reduce harmful noise, and its use is only limited to electrical devices, are in line with the 530-530-71 to 73 part of all requirements. NEG sections related to the entire text all others in "NEC dealer password" in. New requirements needed for the new AC system grounded outlet or branch circuit switch gate on the additional ground fault interrupt (GFl) device.
When you use the new 120/60 volts AC system three significant changes occur.
First: If you are a standard circuit forms, heat-insulated grounding on the conductor is the original half electronic magnetic field is proportionally reduced to ground level.
Second, the earthing system are all is symmetric, which in the grounding system of common mode noise current restricted converted to normal current capacity, thus limiting circuit normal noise voltage. This reduces noise passes through the device's ability to reach the next circuit.
Third, NEC requirements for 120/60 volts alternating current system only provides support for the Assembly have a special connection set of electric equipment. This prevents electrical equipment considerable interference with the same AC systems and branch circuit connection of other devices. Remember: when you use the common inside buildings and AC system completely isolated AC system, from the perspective of non-power is very reliable, because the set is equipped with a compressor of electricalBy now used in a dedicated 120/60 volts alternating current system, but the lights, motors, etc. load and this is not the same, they start and fault situations will cause a branch circuit or feed device switch gate jamming circuit breaker, not simply connected to the auxiliary converters, feed unit and branch circuit system.
How do I do?
The best results is to completely separate converter, auxiliary too strong current, open device, feed unit and branch circuit all installation to a new 120/60 v AC voltage, as already installed devices, which comply with the requirements of the NEC System. This is independent of the other systems inside buildings of unique AC system, it requires the adoption of the Earth conductor (GEC) AC system received the general architecture of the Earth using NEC Earth grounding.
Please note: the entire 12D/60 volts AC system using operation will present a small fault, including those not required strict training will be able to access location. According to NEC, when 120/60 volts AC system used in the General area, you need to make separate settings and confirm.
On a separate set of issues has two requirements: firstly, to have special Sockets and plugs, distributors may not be in stock; second, it is necessary to cut the cable plugs, on existing 120VAC and replace with a new, to improve the safety of the products listed. The second requirement and poses new problems: as the 110-2 parts, recognition and a 110-3, testing, verification, installation and use of equipment; (b) paragraphs, install and use a combination of factors such as the impact must longer operation another NEC. For example: is listed or identified devices but it does not give a valid period cannot be improved. This makes the device no longer belongs to the listed or indicated, and makes himself confirmed the two parts are possible. The only solution is the right of access to electronic security detection, allows to improve device security and operations of the determination of the issue.
If you haven't completed the program, took place before a fire or electrical shock event, exhibition venue will have lawyers to prove all the scene sign level improvement processes are chapter oNEC in this part you need to do change slightly to prove that is listed or identified by the device can be used to improve the standard NEMA 5-15 or. 20-socket, and does not lose the NEC lists, labels or other advantages.
Control noise drone and the grounding
When electrical equipment fully installed in a room, such as audio and video editing room equipment, usually have several mounting bracket, there are a number of signal cables. This installation mode is always involves the drone and the noise problem, and are based on common mode (CM).
When the pulse interference timing or related logic components set and repeat the set of actions, the grounding system of common-mode current and voltage may cause some digital electrical equipment operation. Once the circuit impedance of instability into normal current or voltage, it automatically simulates the signal, and directly affect the control operations and audio/video signals.
Divided into noise of common-mode current and voltage is the crux of the problem, generally refers to by equipment grounding damage NEC or bonding grounding method created by electrical safety issues. One case is the use of single-point grounding method, this method is used to simulate electric appliance, it is difficult to predict its role; in digital equipment and a useless, is true for the respective device shockproof design, when the ground to form additional classification will undermine the NEC made equipment and AC power supply and grounding system.
However, addressing these problems also exist a real and effective measures, and to ensure that the AC power system and device safety grounding. The measures referred to as signal parameters network (SRG), including cable terminal screen with AC power supply and signal level fluctuation protector.
The following starting from SRG to describe each.
Signal parameters screen
General view. If electrical equipment grounding are buried below ground level. You will solves the cross the widest frequency band of grounding. The difficulty is that the plane is generally very difficult to attach objects, but the actual connection costs are very high. However, if you use the grid instead of a plane, not only reduces the high operating frequency limit, you can take advantage of the plane as possible into full play. Remember: the perspective from geology. The grid is actually a hole in the ground plane. But in the actual installation of the grid, the holes of the plane will not become troublesome. Since the introduction of the SRG's practical designs from DC to 25MHz. 30MHz between very effective. This is a very successful broadband grounding method, passing through various types of analog and digital logic commercial audio visual equipment needs full-band frequencies are most effective.
Ordinary SRG includes a series of copper conductor, one to two feet apart, are combined to cover the entire electrical equipment installation of the ground. SRG general installation on the floor, all devices are connected to the washer with crossover. All electrical conduits, equipment grounding and indoor use of independent converters (IT) are connected on the SR9, making a total of all the electrical grounding parameter. Here said all electrical, because separate connection method issues a lot, including electrical safety issues have been deserted. (Auxiliary components of neutral Terminal, metal housing or Cabinet and the green line in the converter. These components of the connection point and jump from the underground, on receiving the SRG independent converters generally placed directly inthe upper portion of the SRG, rather distant install).
Typical structures
In General, the SRG's structure is to use hole-shaped floor (computer room common floor), and in its bottom connection SRG, electrical power and signal wiring. Underground potentiometer is commonly used to adjust the air, i.e. HVAC processing power cooling indoor air.
Hole-shaped floor installation mode you can put the SRG directly installed on the secondary upper floor, or with SRG wire gripper hanging to the floor bracket at the top of the tops. Both effects are good, materials often use AWG # 36 light copper wire or 0.1 (2.54mm) thick, 2.O Ying(50.8mm) width of the copper strip. Divider connection points in 2x2 ft (61X61cm), but can sometimes be slightly larger or smaller, their differences are not easy to be detected.
With or without laying carpet, SRG structure uses a flat sheet of copper gold book. The book about O.030 British time (O.762mm) thick, 2 feet (61x61cm) wide, can give each one a welding frequency divider. The SRG directly usable for floor surface or antistatic mats. (Your electrical room also uses this carpet, isn't it?) Cut carpet of t-shaped slot can be named grounding copper tape or patch cord through the carpet, and welded to the underground of SRG gold flakes, then put the carpet edge down folded.
Pulse protection
From a physical damage, the electrical equipment is the biggest threat comes from lightning-induced voltage suddenly change phenomenon, often called the pulse. Although the pulse and electrical installation of geographical location, but it really is prevalent throughout the United States electrical appliances and a major threat. If you want to know the extent of this threat, please refer to the ANSI/NFPA780, 1992 international lightning-protection legislation.
For construction of electrical equipment, direct energy building or input AC power conductors were insufficient to produce destructive pulse current or voltage, and the head or the nearby cloud collision down often destructive. Because many of the normal installation includes all each connection line equipment, there are enough opportunities to produce damage and lightning currents to the conjunction of near-field systems. This is the inevitable electronic field phenomena (coupled capacitance), magnetic field should feel. But these phenomena through proper shielding and grounding, connections, and pulse protection technology and other methods to mitigate.
Pulse can be coupled to the building wiring systems and electronic control of the load unit or signal processing cables. The amount is calculated by the pulse and the connection closed area is proportional to pulse volume. Closed area is larger, then lightning release of pulse current and voltage will increase.
From the victim machine, pulse threat comes mainly from the AC power input and signal or control cable interface both. Therefore, from the conductor interfaces to access to the victims of pulse current in the device, and from the other end and also into the conductor. So affected device looks in conjunction with the pulse of the middle of the loop. This may explain why only a connector with the added protection and cannot protect equipment against lightning damage.
Don't forget that with the increase of computer application, control or signal interfaces generally use computer industry standards. Note: unless the problem is due to the installation of certain special interface Jack card, this card is not a standard signal.
Appropriate pulse protection requires both the pulse protection facilities in electrical equipment, also need to put it in the AC power supply and control or signal cable connector. This approach often in AC power input to the metal oxide varistor protection forms based. Signal level interface can use a specially designed protective circuit to TrallZprbs gas pipes, series resistor or impedance and ordinary reactor coils are integrated and and AC power interface protection performance. For example, RS-232 digital signal interface requires a for RS-232 special design of pulse protection, and after testing of AC power connector pulse protection while in use and cannot be replaced with other things, otherwise it will damage the signal interface. The best protection is to AC power and signal protectors also installed to or through the ground received protected electrical metal shell or every body. In most cases, the installation of a rack of metal appliances can meet this requirement, but this approach for a number of combinations is even more necessary.
Pulse protection unit general business for industry-standard signals, but not for dedicated signal. Therefore special application requires special design. Building power system within the AG must be pulse protection, to ensure that reach AG power circuit of the electronic load device of the pulse) level drops to its lowest point. Electronic load device protection cannot be high-energy Chen) played the role of full protection. But the better protection of low level pulse. Use of existing methods in the same package of equipment level cannot provide high notch performance and high energy level control performance.
Recommends that the instance is from a building SEQ begin, install a conductor is called secondary lightning protection (lightning arrester) device. SEQ metal frame or body must be a reference point for pulsed current. In General, building permit instance is the protector with AC capacitor parallel connection to every piece of grounding line. This usually means the Wavefront additional capacitors sometimes as part of the overall protection is built into the appliance. Most such protective devices are suitable for 2600VAC system, using single or three phase plug.
On the branch circuit is located in the SEQ and damaged electrical load device between the bezel and switch between a pulse protector, it is recommended that you use the instance to encourage similarpulse protector. Each case, the protector of all lines and equipment grounding of shunts, switch plates or metal shell bezel or box. Device interface protection of pulse protection level before you can use the back of the branch circuit. Recommended that the instance is installed-pulse protection socket, or the protector/lightning first insert a normal socket, and then damaged electrical load devices plugged into it. All these measures will be continuous streaming and then decay from the power distribution system reaches the SEQ pulse) level so that it fell to auxiliary protectors can be applied. The rest of the lower level is by special facilities and auxiliary protectors, clear away, this auxiliary protectors used in AC power to the electrical load device of the exit, with the device's signal interface protection combined use.
Cable shield Terminal
In analog circuit and low-frequency signal processing, there is a golden rule, that is only in the end shield. But because of the high-frequency characteristics of the circuit, this is not done for digital signal circuits of the instance. If you use the shield attenuation as lightning caused by interference of lab coupled, this is not a simulation of the circuitProposal instance.
In digital circuits, you require the cable shield at either side of the protective grounding for field and keep the cables on the consistency of high-frequency signal. Don't worry and cable digital signal is connected to the cable shield currents, because in the associated electrical frequency, the two currents run in shielding of Interior and exterior, almost no gravity separation. This is the electromagnetic field of the feature, is also a function of the skin effect. In fact, most of the digital signal cable, coaxial cable, along with multi-point grounding shield and does have the side effect of improved good lightning protection measures.
Telephone company in the user's interchange or indoor are equipped with grounding cable shield, which is installed by NEC regulatory lightning bolt.
Power quality
In the phone cable shielding used is a pair of mutually bound line of devices, each with cable, wire or cable, or racks pulse protection device (SPD). Independent grounding shield's end just use a few micro-la capacitor can dispose of unneeded, common-mode current caused by the cable shield currents.
This prevents the DC and most audio (including AC power system harmonics), but it allows high frequency pulse) current easily pass. As a result, shielding measures by like an infield coupled noise attenuation and pulse, but not from the circuit ends ground potential, and DC and DC-current system-dependent effects of common-mode current.
Shielding current problems can also recognized through many other technologies, such as in use between shielding and grounding, cable Tranzorbs Terminal use opto-coUpLers, cable using common mode inductance coil or signal separation converter.
Finally, if only in the cable installation grounding shield, then place the cable ends of the Earth within the metal pipe, you can get both a grounded shield effect (such as in-field protector). This example creates a two-stage screening system, its design greatly increases e-field circuit shielding. In this approach used in the circuit or channel types include electronic metal tubing (EMT), metal tube (IMC) and bracket metal tube (RMC), followed up on the order of installation.
Note: common-mode noise current in decay, galvanised metal pipe to more than lead pipe market.
Digital logic and to SMPS based appliances are being or have replaced analog circuit electrical appliances. New electrical design has many advantages, but relatively easy to produce accessible AC power output grounding system and is used to connect components and systems for additional signal level cable electronic noise. New and old appliances design are easily damaged lightning generated effects of pulsed current and voltage, current and voltage can be transferred to the electrical wiring of AC power input, the signal cable and the ground system.
If you understand how AC power problems affect electronic load device, you can decide exactly what kind of power you need adjusting device. CBEMA curve of development significantly contribute to the development of the conditioning equipment, not only for the original analog electrical or modern appliances, digital logic.
When you use the new digital appliances, it should be out old electrical grounding connection, various methods of screening. In other words: strict compliance with the provisions of the NEC; do not use a separate ground grounding electrode connection; cancel a single point of grounding system, because you must use a broadband signal parameters network; avoid end signal cable shielding and grounding, because the digital signal requires both grounded; particular attention: If local often lightning to occur, you must give the new electric AC power supply and signal circuit provides proper pulse protection device. Just follow this guide carefully, you can ensure that electrical grounding system safely without lamb.