Electromagnetic compatibility civil products EMI during verification guide_Century Wisdom (Suzhou) Testing Technology Co., Ltd

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Electromagnetic compatibility civil products EMI during verification guide

Release time:

2023-04-07 15:15

Source:

For electromagnetic compatibility testing, the first task is to ensure the accuracy of the experiment. How to ensure the accuracy of the experiment, according to the requirements of GB/T 27025 laboratory system, firstly, all equipment/systems need to be calibrated regularly, and secondly, during the two calibrations, the performance of the equipment/system needs to be checked.

Calibration: A set of operations under specified conditions, the first step is to determine the relationship between the measurement provided by the measurement standard and the corresponding display value, and the second step is to use this information to determine the relationship between the measurement results obtained by the display value, where the measurement standard provides the measurement value and the corresponding display value have measurement uncertainty.

Period verification: the operation of testing equipment, facilities and systems to verify whether their main measurement characteristics or functions can continuously meet the method requirements or specified requirements according to the prescribed procedures between two adjacent calibrations or during use.

1. Verification method for power port conducted disturbance measurement system

Test connection:

Verification:

a) Connect the comb generator to the equipment under test (EUT) port of LISN for measurement;

B) Switch the comb generator to the L line and N line in turn through the LISN power converter, and perform pre-scan measurement of PK and AV on the corresponding power lines respectively;

c) The laboratory shall measure QP and AV at the corresponding frequency points of L line and N line of LISN according to the specified frequency points, and record the results.

Judgment:

The measurement (or statistical value for a period of time) recorded for the first time after the measurement of the measurement system is used as a reference value, and if the difference between the measurement and the reference value verified during the subsequent period is within the range of the measurement uncertainty of the laboratory, the period verification result is qualified.

2. Loop antenna system (LLAS) verification method

Test connection:

Verification:

In the range of 9kHz ~ 30MHz, as shown in the figure above, verify the coefficients of the three-loop antenna at 8 different positions of the dipole. The dipole antenna should be in the same plane as the loop antenna. The deviation between the open circuit voltage V output by the signal source and the measured current I of the receiver dB(Ω)= 20lg(V/I).

Judgment:

The measured confirmation factors at 8 positions of each large loop of the 3 large loop antennas are compared with the reference confirmation factor. If the deviation is within ± 3dB of the reference confirmation factor, the period verification result is acceptable.

3. Verification method of disturbance power measurement system

Test connection:

Verification:

The frequency step of the comb source is set to 5MHz or as determined by the laboratory. The verification procedure is the same as the disturbance power measurement (30MHz ~ 300MHz) procedure in the GB4343.1-2018. Several fixing positions are selected recommend the absorption forceps, such as 0cm, 100cm... etc.

Judgment:

4. Verification method of CDNE measurement system

Test connection:

Verification:

The frequency step of the comb source is set to 5MHz or determined by the laboratory. The verification procedure is the same as the CDNE measurement (30MHz ~ 300MHz) procedure in the GB17743.

Judgment:

5. Verification method of radiation disturbance measurement system (30 MHz ~ 1GHz)

Test connection:

Verification:

The comb generator is placed on a table 0.8m high at the center of the turntable, the azimuth angle of the turntable is set to 0, and the measuring antenna is 10 m (or 3 m) away from the transmitting antenna. The frequency step of the comb generator is set to 5 MHz or as determined by the laboratory. The antenna is at a height of 1m from the ground for vertical and horizontal period verification.

Judgment:

6. Verification method of radiation disturbance measurement system (above 1GHz)

Test connection:

Verification:

The comb generator is placed on a table 0.8m high at the center of the turntable, the azimuth angle of the turntable is set to 0, and the measuring antenna is 3m away from the antenna. The frequency step of the comb generator is set to 100MHz or as determined by the laboratory. The verification procedure is the same as the procedure of radiation disturbance measurement (above 1GHz) in GB/T9254.

Judgment:

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