When the air conditioning, the indoor fluorescent light will be dimmed for an instant phenomenon, this is because a lot of current flowing air, the rapid voltage drop, using the same power of fluorescent affected. There will be a vacuum cleaner when the radio "Para Para" noise. The reason is the engine of the weak vacuum cleaner (low-intensity high-frequency) voltage / current change through the power line to pass into the radio to put out in the form of noise. Such a device produced by the voltage / current through power lines, signal transmission line and
14 datasheet and affect the other device, this voltage / current change is called "conduction disturbance." So to remedy, commonly used method is to place the source and
14 price and the receiver are on the power lines, install a filter to prevent the transmission of conducted interference. In addition, when the signal line noise occurs when the signal cable to optical fiber, can also be cut off transmission channels.
when the motorcycle from the nearby road through the TV there will be snow-like interference. This is because the motorcycle ignition pulse current produces electromagnetic waves, spread to the nearby space and
14 suppliers and then to the TV antenna, circuit, resulting in interference voltage / current. Spread through space like this, and other equipment useless circuit voltage / current, resulting in harms interference is called "radiated interference." As the transmission of space, the method to solve radiation interference filter in addition to the aforesaid, should also be effective for shielding equipment.
As noted above, the source of interference is the voltage / current unnecessary changes, which passed through the wire directly to other devices. Harm, this is called "conduction disturbance." In addition, the voltage / current changes resulting from electromagnetic waves transmitted through space to other devices in the circuit or wire unnecessary voltage / current, and the harm of interference called "radiated interference." However, not actually that simple distinction. For example, word processors or computers and other computing devices of the source of interference, although the internal circuitry on the mobile devices digital signal voltage / current, but these methods interfere with conduction through the power line interference or signal line leak, directly passed to the other equipment. These wires also produce interference in the form of electromagnetic radiation to endanger nearby devices. And computing devices within the circuit itself is also produced electromagnetic waves, interference of radiation in the form of a danger to other devices.
Finally, do some of the radiation interference more detailed description. According to antenna theory, if the wire length and wavelength equal, prone to electromagnetic waves. For example, a few meters long power cord will have a VHF band (30 ~ 300 MHz) radiation interference. Lower than this frequency in the band, due to longer wavelengths, when the power cord when the current flowing through the same, not too strong electromagnetic radiation. Therefore, the low frequency band below 30 MHz is mainly conducted interference. However, with the power line conducted interference will interfere with the magnetic field around, so bring interference to AM radio.
In addition, as noted earlier, due to leakage of VHF broadband interference in the power cord into electromagnetic waves can spread to the space, conduction disturbance radiated interference become more important than the issues. At higher frequencies than this, more water than the size of the power cord circuitry inside the device will produce radiation interference, damage other equipment.
All in all, when the equipment and wire length than the short wavelength, the main problem is conducted interference, when their size is smaller than the wavelength long, the main problem is the radiation interference.