Wednesday, December 15, 2010
【 Weak current College 】 power noise interference treatment 】
In General, power supply noise interference of transmission can be divided into the following two categories:
1. normal mode (NormalMode): simply pass mould, referring to the second set of input power line noise between. These noise mostly consists of a short or a static power converters, interference, when these interference with normal signals overlap, the equipment component is unable to tell, because normal signal is to die for state exists.
Second, common mode (CommonMode): short for common mode, referring to the power supply and ground connection between clutter. This part of the noise causes mostly because of the grounding, lightning, poor design, broadcast radio, motor electromagnetic or ground fault caused by such factors.
The second mode is to noise disturbance of transmission and distinction, usually we will collation to electromagnetic interference (EMI, ElectromagneticInterference) and radio frequency interference (RFI, RadioFrequencyInterference), etc. General home power issues occurs, generally is electromagnetic interference and radio frequency interference, power, stability, etc. Want to solve these problems, and rely on audio equipment internal power line is usually not enough and, therefore, will have power for handling equipment. However, each audio mystery House of the problems encountered are different, the market power handling equipment types and quite a lot, so this how to choose a suitable power supply equipment, even own what should purchase this product, also is our 「introduction thorough research 」. Next, we will all experience a power problem sorting out, so that readers can more easily understood further understanding power processor.
Power handling equipment common species present on the market of power processing equipment, the functions are surge absorber, power filter, isolation transformers, power supply, voltage regulators, etc. They are individually responsible for the different functions and roleare described below.
Surge absorber (SurgeAbsorber)
Surge Absorber's main role is used to suppress excessive surge voltage. Under normal conditions, the power company to the user in the power supply voltage is 110V, however in some circumstances will appear at the moment over normal voltage value, as it were struck by lightning or power failure, and other factors. Although the power company is equipped with protective measures, but because of their response speed and protection level has some limits, so there are some spikes might instants are delivered to the user's home. In addition, the power of these protection devices in 「introduction of actuators and duplexing 」 moments often produce some surge, there is the home of the power switch at the moment of the action, will surge as well.
These unusual spikes, although only at the moment, but the process of voltage and current are often higher than normal, serious enough to destroy the home of many electrical products, such as computers, TV and audio equipment, etc, because these appliances working voltage are relatively low, which can withstand surge capacity is relatively low. Surge Absorber according action principles, characteristics and can be divided into the following three categories
I. synthesis of surge absorber: mostly applicable to lightning, absorbing current range in between 500A-500KA.
Second, semiconductor-surge absorber: can be divided into OVaristor (absorbed current range 200A-20KA), SiCVaristor (absorbed current range 100A-10KA), SeSurgeAbsober (absorbed current range 10A-1KA), bidirectional Zener diode (absorbed current range 1A-50A).
3. filter type surge absorber: divided into CR (capacitance and resistance, current range 1A-50A) and CL (capacitor and inductor, absorbs the current range of 10A-1KA) second circuit, this is the sound power processor most common surge absorption device.
Power filters are primarily intended to eliminate the noise inside the power supply, power supply noise can affect the performance of a sound audio equipment, general assertion that it will make the sound, sound field positioning effects. Usually filter capacitance and inductance is to use a group select circuit synthesis (LC), allows a specific frequency signal through, non-specific frequency signals are blocked by attenuation or. Most often used by EMI filter, noise about 50KHz above a relatively good filtering effect and noise attenuation specifications about only about 40dB. The disadvantage is the event of large amplitude or surge noise, easy to make because of saturated inductance coil and reduce their noise attenuation characteristics, but when an in-line EMI filter only works will therefore improve. The introduction of power processing equipment, as long as it is designed for filtering products are used in this way. In addition, power filter use remember must be grounded, so you can play to their effectiveness.
Isolating transformers for General refers to prevent noise transformers. The power supply into the various types of electrical products, although will first go through power supply transformer, but still high-frequency noise by transformer primary and secondary coils between capacitive effect, magnetic coupling or radiation, etc., through subordinate into electrical product lines. Therefore, to prevent noise interference is the most simple and effective method is to use the isolating transformer isolated from them. In various noise reduction of power equipment, isolating transformer effect is best because the isolating transformer apart from eliminating power, fluorescent starter, air noise of various radio frequency, it instantly about the power switch or surge has very good filtration results, just filter out the frequency and the aforesaid 「introduction power filter 」. Isolation transformer if to isolation characteristics to distinguish, can be divided into the following three
1. insulation transformer: this is inBetween primary and secondary, plus a layer of special insulators for the primary transmission to secondary noise to be measured. However, in this way and could not be isolated from all the noise, like power switching action, and so on-die interference will not be able to filter out.
Second, the shielding transformer: apart from with the construction of insulating transformer, primary and secondary coils perimeter and using gold foil paper insulation materials to be coated to reduce second coil winding between capacitive effect. Compare with insulated transformer, shielding transformer for high-frequency interference characteristics while better, but still unable to remove flux mode noise.
Third, noise filtering out Transformers: that is in addition to the static, and in most perimeter plus electromagnetic shielding. Noise filtering out transformers can effectively isolate the common mode interference, but about as AC conduction of circular die interference, only attenuation capacity. Noise filtering out the core transformer, power transformer in General is not the same, its limitation through magnetic rate after special design to a specific frequency (a few KHz) above will plummet, so in this particular frequencies above the noise will be relatively attenuation, the higher the frequency, the greater the amount of attenuation. If you cannot use in-line with LC filter, the result will be better. In this introduction to audition for the equipment for the isolation of design products that is in this case.
According to long-term study of new electronic transformer kin indicated that Mr. Wu-transformer efficiency and core (Core) form is not absolute, that is to say both EI, C, r, or ring, cored, unrelated to the performance of the contingent. The core of the form will only be related to size and magnetic fields, such as television is using a transformer, R-Core because it consists in its volume can be extremely flat, and also makes its effect of magnetic field in getting to the cathode ray tube (CRT). The real impact of the core material, steel sheets of material, the better the efficiency is higher.
Power regulator power supply regulator's main role is to provide a constant voltage supply electrical products. Common AC regulator is roughly divided into inductive, connector changes-, magnetic saturation, phase control, linear compensation HES, among these, the phase control-the most visible, it is the use of SCR and TRIAC etc unique cenduction characteristics of electronic components for the phase control control its gate extremely breakover angle in order to achieve the purpose of the regulator. It's the most significant feature is the entire control processes all circuits, in addition, due to its output wave type is not a sine wave, therefore need plus filter to make the output waveform for a sine wave. Although the majority of electrical products (including Hi-End audio) has stabilized, the introduction of some power processor also claims that there is a power supply voltage, but if such harsh perspective judge 「introduction voltage 」, sorry, they are not bypassed.
Key and cognitive on audio enthusiasts, in various forms, actuation principle of power processing equipment, is only there for one purpose-that is how to make audio equipment issued more pleasant voice. The purpose of that difficult in fact it's not hard to say simple or too underestimate the power of the Hi-Fi! although power processing equipment more is just a pile of steel sheets, enameled wire, resistors, inductors, capacitors and insulation material together, but these elements on the level of efficiency and effectiveness of noise reduction, has a decisive impact. Of course, in addition to the material, the other like a coil around the implantation, steel sheets of fixations, the insulation material of location and quantity, circuit design and configuration elements and so on, are also important key advantages and disadvantages. We do not want to see the readers spend a lot of money, and did not receive his expected to achieve results, but should look at the current 「introduction thorough research 」, on issues related to the power supply and processing equipment has further awareness, further discussion is needed, or they should choose what type of power processor.
Companies with high-voltage surge protection, but because of their response speed and protection level has some limits, so there are some spikes might instants to user home; at the same time, these protection devices in 「introduction of actuators and duplexing 」 moments often also have a number of spikes. In the past we often erroneous perception that the ring-type transformer efficiency must be the best, in fact, the core of the form will only be related to size and influence of magnetic field, the real effectiveness of the core material, steel sheets of material, the better the efficiency is higher.