| Popis: |
Most conducted forms of intrasystem EMI result from various equipment or systems sharing the same source of AC power mains (6). Here, an electrically noisy source may pollute the power distribution wiring by injecting broadband conducted emissions into wires that also feed other potentially susceptible equipments. In this instance, the common-mode noise voltage is generated across the power distribution source and circuit impedance and is therefore “seen” by all equipment connected to the power source. Another mechanism involves common impedance coupling in which two or more circuits are fed from a common regulated or unregulated power supply with an (usually unintentional) impedance element appearing in (i.e., in common with) both circuits. For example, this latter situation often occurs when two circuits share a common return path, such as a ground plane, for the power current, determines the level of induced voltage and the susceptibility of the interference depends upon the level of the path impedance, which, for a given current, determines the level of induced voltage; and the susceptibility of the potential victim circuit. Power mains pollution can also occur if the power lines are electromagnetically contaminated as a result of the coupling of radiated emissions, such as the signals from licensed transmitters, into the lines. The radio frequency (RF) noise is thence conducted into equipment circuits via the power-line conductors. |
