The 3C certification requirements for electromagnetic compatibility (EMC) primarily focus on electromagnetic interference (EMI) characteristics, without explicitly specifying electromagnetic interference immunity (EMS) capabilities. Specific testing items vary depending on the equipment type. The following is a detailed explanation:
Core Contents of Electromagnetic Compatibility Requirements
EMI (Electromagnetic Interference Characteristics) Requirements: 3C certification currently only specifies requirements for the electromagnetic interference characteristics of products. This means that the electromagnetic interference generated by the equipment during operation must meet standard limits to avoid adverse effects on the surrounding environment or other equipment. For example, audio-visual equipment and information technology equipment must meet limits on interference voltage, radiated interference field strength, and harmonic current within a specific frequency range.
EMS (Electromagnetic Interference Immunity) Requirements: Current 3C certification standards do not explicitly require electromagnetic interference immunity capabilities. This means that the performance stability of equipment under external electromagnetic interference is not currently included in the assessment scope.
EMC Standards and Testing Items for Audio-Visual Equipment
Applicable Standard:
GB/T 13837-2012: Specifies the limits and measurement methods for radio interference characteristics of sound and television broadcast receivers and related equipment.
GB 17625.1-2012: Specifies harmonic current emission limits (input current per phase ≤ 16A for equipment).
Test Items:
LCD TVs: Interference voltage, radiated interference field strength, and harmonic current must be tested. If the product has multiple functions (such as smart TVs), the testing requirements for information technology equipment must also be considered.
Other audio-visual equipment: Such as tuners, radios, audio-visual recording/playback equipment, etc., must be tested according to all applicable items specified in the standard to ensure that electromagnetic interference characteristics meet the limits.
EMC Standards and Test Items for Information Technology Equipment
Applicable Standards:
GB/T 9254-2008: Specifies radio interference limits and measurement methods for information technology equipment.
GB 17625.1-2012: Same as audio-visual equipment, specifies harmonic current emission limits.
Test Items:
Three core tests:
Interference voltage: Test frequency range 0.15MHz-30MHz.
Radiated interference field strength: Test frequency range 30MHz-1000MHz. Harmonic Current: Harmonic emission limits when the input current per phase of the test equipment is ≤16A.
Impact of Key Components on Electromagnetic Compatibility (EMC)
The performance of the following components directly affects the EMC of the equipment and requires close attention during design and production:
Tuners, Oscillators: May generate high-frequency noise; interference must be suppressed through shielding or filtering design.
Switching Power Supplies (Switching Transistors, Transformers, Rectifier Diodes): Switching operations easily generate harmonics and EMC; circuit design needs optimization or the addition of filters.
Power Supply Filters, Interference Suppressors: Used to reduce harmonic pollution to the power grid and the intrusion of external interference.
RF Modulators, Power Amplifiers: Radiated interference needs to be controlled in high-frequency signal processing stages.
Power Cables with Ferrite Rings, I/O Cards, HDMI Cables: Electromagnetic leakage should be reduced through ferrite rings or shielding design.
Crystal Oscillators, Servo Motors, Transformers: Their electromagnetic characteristics must be ensured to avoid becoming sources of interference.
Touch Chips: Their own noise must be suppressed to avoid interfering with touch signals.
3C Certification Catalog Scope and Inquiry Method
Catalog Classification: The 3C certification catalog is divided into 11 major categories, including wires and cables, household appliances, electronic products and safety accessories, lighting equipment, vehicles and safety accessories, etc.
Audio-visual and Information Technology Equipment Scope:
Audio-visual equipment: such as speakers, power amplifiers, recording/playback equipment, television receivers, set-top boxes, etc.
Information technology equipment: such as computers, servers, display devices, printers, scanners, power adapters, etc.
Inquiry Method: You can check whether a specific product requires 3C certification through the official website of CQC (China Quality Certification Center) (path: Product Certification - CCC Product Certification - Certification Scope).
