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Detailed explanation of conduction emission testing

Company News2023 23Asia/ShanghaipmMon, 07 Aug 2023 18:05:29 +0800 08 08202383106 07 07pm23 4136

What is conducted emission testing?

Any non portable device that transmits its common mode current and voltage noise to interconnected devices through power cables or signal cables is called conducted emission, also known as conducted interference.

The following content refers to GB/T 9254.1-2021 regulatory specifications.

The conducted emission test is divided into two types based on the test port of the tested equipment: the power end and the signal end.

Power end testing: for the conducted interference caused by connecting the power port of the testing equipment to the AC or DC power grid.

Communication end testing: For the conducted interference caused by the communication port connection of the testing equipment (such as network port, ISDN port, etc.), there is no requirement for this type of audio and video port.

Conducted emission testing is divided into two levels based on the operating environment of the tested equipment, A and B, with required limits.

Class A: Equipment used in non household and non directly connected residential low-voltage power supply facilities.

B-class: Equipment used in household and directly connected to residential low-voltage power grid facilities.

Usually, equipment in industrial environments is defined as Class A limits, which are used in more complex environments and are not as strict as Class B for the conducted interference of the equipment itself. Therefore, Class A limits have looser requirements and are easier to pass. However, the equipment nameplate needs to be labeled with a warning sign - (Warning: Operating this equipment in residential environments may cause radio interference).

Requirements for conducting emission test line values.

Power end limit (coupling device is AMN)

Frequency band	A-level		B-level
	Quasi-Peak(QP)	Average Value(AV)	Quasi-Peak(QP)	Average Value(AV)
0.15 MHz~0.5 MHz	79 dBuV	66 dBuV	66~56 dBuV	56~46 dBuV
0.5 MHz~5 MHz	73 dBuV	60 dBuV	56 dBuV	46 dBuV
5 MHz~30 MHz	73 dBuV	60 dBuV	60 dBuV	50 dBuV

Communication end limit (coupling device is AAN)

Frequency band	A-level		B-level
	Quasi-Peak(QP)	Average Value(AV)	Quasi-Peak(QP)	Average Value(AV)
0.15 MHz~0.5 MHz	97~87 dBuV	84~74 dBuV	84~74 dBuV	74~64 dBuV
0.5 MHz~30 MHz	87 dBuV	74 dBuV	74 dBuV	64 dBuV

Peak value (PK): The highest value per unit time. Quasi peak value (QP): The weighted average value (AV) of the signal level based on the repetition frequency of the peak signal. Average value per unit time* The relationship between the three is PK value>QP value>AV value.

详解传导发射测试

Conducted harassment test setup (based on the example of desktop EUT):

1. EUT should be arranged according to the actual working state, and all ports must be connected to external devices. The distance between EUT and AMN should be 0.8m, and the connected power cord should also be 0.8m.

If the connecting wire is too long, it needs to be tied back and forth without feeling, with a bundling length not exceeding 0.4m and a spacing requirement of 0.8m.

3. If other AEs are needed to assist in testing, the AE's power supply needs to be supplied through another AMN to avoid the AE's power supply noise affecting the testing.

4. The distance between EUT and AE should be ≥ 0.1m, and the EUT should be placed on a wooden table 0.8m high.

5. The back of the EUT, AE, and related cables should be 0.4 meters away from the vertical RGP, and the AMN and AAN used should be overlapped to the vertical RGP metal plate.

6. The part of the signal cable hanging on the back of the table should be 0.4 meters above the horizontal RGP. If the signal cable is too long, it needs to be tied back and forth without feeling, and the tying length should not exceed 0.4 meters.

Note: Test Equipment (EUT), Auxiliary Equipment (AE), Artificial Power Network (AMN), Asymmetric Artificial Network (AAN), Reference Grounding Plate (RGP).

详解传导发射测试