What is conducted interference and what is radiated interference-EEWORLD

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Conducted interference It is mainly the interference signals generated by electronic equipment that interfere with each other through conductive media or public power lines;

What is radiated interference?

Radiated interference refers to the interference signal generated by an electronic device being transmitted to another electrical network or electronic device through spatial coupling.

In order to prevent the electromagnetic interference generated by some electronic products from affecting or destroying the normal operation of other electronic equipment, governments or international organizations have successively proposed or formulated some regulations or standards on electromagnetic interference generated by electronic products. Products that meet these regulations or standards can be called electromagnetic compatibility (EMC). Electromagnetic compatibility (EMC) standards are not constant, but are changing every day. This is also a means often taken by governments or economic organizations to protect their own interests.

Conducted interference is generally transmitted in the circuit in the form of voltage or current. Figure 6 is a basic method for testing conducted interference generated by electronic equipment, or several ways of transmitting conducted interference through power lines. In Figure 6, the electronic equipment represents the interference signal source, CI represents the common mode interference signal, and DI represents the differential mode interference signal; V1, V2, and V3 respectively represent the connection method for measuring the interference signal with an instrument, and the low-pass filter is added to facilitate the testing of V1, V2, and V3; R1, R2, R3, and R4 are the grounding resistance of each electronic equipment, including the resistance between the earth. The grounding resistance is generally a few ohms to tens of ohms, and its resistance value is related to the installation of the ground wire and the soil structure of the ground surface; C1 is the capacitance of the electronic equipment to the earth, and its capacity is related to the volume of the electronic equipment and the distance from the ground, generally a few picofarads to thousands of picofarads.
From Figure 6 we can see: V1=CI-DI, V2=CI+DI, V3=DI
From Figure 6 we can also see that the differential-mode interference signal DI is transmitted through the two power transmission lines of the electronic equipment, so it must be isolated by a low-pass filter; and the common-mode interference signal CI is transmitted through the capacitor C1 of the electronic equipment to the ground. Since the capacity of C1 is generally very small, C1 has a large impedance to low-frequency common-mode interference signals. Therefore, in the low-frequency band, the common-mode interference signal is generally easy to suppress, but in the high-frequency band, it is much more difficult to suppress the common-mode interference signal than the differential-mode interference signal.