Conduction Interference Test Results of Chargers

　　Conduction interference testing is a critical evaluation process for chargers, aimed at assessing the electromagnetic disturbances that are conducted through the power lines connected to the charger. These disturbances can disrupt other electrical and electronic equipment sharing the same power network, leading to malfunctions or performance degradation. The test results provide valuable insights into the charger's electromagnetic compatibility (EMC) and help identify areas for improvement.

　　During conduction interference testing, chargers are typically subjected to a series of standardized procedures in accordance with international EMC standards, such as CISPR 22 and EN 55022. The test setup involves connecting the charger to a line impedance stabilization network (LISN), which provides a stable impedance to the power source and isolates the test equipment from external electromagnetic interference. The LISN also measures the conducted emissions from the charger across a specific frequency range, usually from 150 kHz to 30 MHz.

　　The test results are presented in the form of graphs or tables, showing the measured conducted emissions levels against the limits specified in the relevant standards. If the measured values exceed the allowed limits, it indicates that the charger has significant conduction interference issues. Common sources of conduction interference in chargers include the switching power supply circuits, which generate high-frequency harmonics during operation. These harmonics can couple onto the power lines and propagate through the electrical network.

　　Analyzing the test results can reveal specific frequency bands where the interference is most pronounced. For instance, if there are excessive emissions in the lower frequency range (around 150 kHz - 1 MHz), it may suggest problems with the input filtering circuit. On the other hand, higher frequency emissions could be related to the layout of the printed circuit board (PCB) or the design of the switching components. Based on the test results, engineers can make targeted modifications to the charger's design, such as improving the filtering components, optimizing the PCB layout, or adding shielding measures, to reduce conduction interference and ensure compliance with EMC standards.

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