1: GB4343-1995 "Measurement methods and control values for wireless communication characteristics of electric and electric hot water appliances, pneumatic tools, and similar household appliances for household appliances and similar main purposes" was published on August 25, 1995 and implemented on December 1, 1996

2: GB4343.2-1999 "Regulations for Electromagnetic Compatibility Testing of Electrical Products, Pneumatic Tools and Similar Equipment - Part 2: Immunity" This specification was published on March 23, 1999 and implemented from April 1, 2000

3: GB "Limits for Harmonic Current Emitted from Low Voltage Electrical Appliances and Electronic Products (Machine Equipment with a Voltage of £ 16A per Phase)" This specification was published on February 9, 2003 and will be implemented from May 1, 2003. Replace GB

Content

To ensure excellent electromagnetic compatibility testing of the product, professional consideration must be given to the design scheme related to electromagnetic compatibility testing.

. The electromagnetic compatibility testing design plan generally includes the following multiple levels of content

1. Grounding wire design scheme

Many interference signal problems are caused by grounding wires. As the potential difference of grounding wires is the standard potential difference in the operation of all power circuits, if the grounding wire design scheme is not good, the potential difference of grounding wires will be unstable, which will cause common faults in power circuits.

. The purpose of the grounding wire design plan is to ensure that the potential difference of the grounding wire is as stable as possible, and thus eliminate the influence conditions

2. PCB circuit board design scheme

Regardless of whether the machine equipment causes interference signal transmission points, is exposed to external influences, or has mutual influence between power circuits, the PCB circuit board is the core of the problem. Therefore, designing a good PCB circuit board has key practical significance to ensure the electromagnetic compatibility testing of the machine equipment. The purpose of the PCB circuit board design scheme is to reduce the electromagnetic wave radiation and sensitivity to external influences caused by the power circuit on the PCB circuit board, and to reduce the mutual influence between the power circuits on the PCB circuit board

3. Filter Design Scheme

For all machine equipment, filters are one of the core technologies for processing interference signals.

. Due to the fact that the transmission lines in machine equipment are highly efficient receivers and radiation source wireless antennas, the vast majority of radiation source emission points caused by machine equipment are maintained based on various transmission lines, and external influences are usually first received by the transmission lines and then connected to the machine equipment. The purpose of the filter is to eliminate this electromagnetic interference on the transmission line, avoid electromagnetic interference from the power circuit from being transmitted to the transmission line, rely on the radiation source of the transmission line, and also avoid the electromagnetic interference received by the transmission line from being transmitted to the power circuit

4. Design scheme for shielding and overlapping steel bars

For the vast majority of machinery and equipment, shielding is necessary.

. With the increasing frequency of power circuit operation, simply relying on PCB circuit board design schemes usually cannot consider the provisions of electromagnetic compatibility testing specifications. The shielding design scheme of the main box has many differences from the traditional overall design. Generally, if the regulations on magnetic shielding materials are not considered in the overall design, it is impossible to add the actual shielding effect to the main box. Therefore, for contemporary electronic product design, it is important to consider the problem of shielding from the beginning

New detection projects

The new detection projects for electromagnetic induction emission points (EMI) include:

① Transmission (CE) (150kHz~30MHz) ② Intermittent impact on working voltage (clicking sound) (150kHz, 500kHz, 1.4MHz, and 30MHz) ③ Impact on output power (30MHz~300MHz)

④ Harmonic current (2-40 pulse currents)

⑤ The new testing items for Electromagnetic Induced Immunity (EMS) of Flicker are:

① Electrostatic discharge immunity ② Immunity to radiation source magnetic field (80MHz~1000MHz) ③ Electrical fast transient/single pulse group immunity ④ Surge (lightning strike) immunity ⑤ Immunity to introduced current (150kHz~230MHz) ⑥ Immunity to working voltage dips and short duration interruptions