Detailed explanation of the national standard GB/T 17626 for EMC testing

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Detailed explanation of the national standard GB/T 17626 for EMC testing [Copy link]

Detailed explanation of the national standard GB/T 17626 for EMC testing

Author: wcc149 Source: Electronic Circuit Development (WeChat Official Account)

0. Introduction

Recently, several boards of the company need to be certified, and EMC testing is naturally indispensable. Since the test is to be done, there must be a standard. Whether it is consumer electronics, industrial control, automotive electronics, or military electronics, the EMC test standards required by these working environments are different, and each test is divided into many levels. Should contact static electricity be 6kV or 8kV, and should air discharge be 8kV or 15kV? What EMC tests should my product undergo? What level should it be achieved? Let's learn about the national standards for EMC testing! The previous article introduced "Detailed Explanation of Electronic Product Certification Types". This article introduces the GB/T17626 series of relevant national standards involved in EMC testing. At the end of the article, there is a download address for the electronic document of the GB/T17626 national standard .

1. What is EMC testing?

EMC, or Electro Magnetic Compatibility, mainly includes two aspects: EMS and EMI.

• EMS refers to electromagnetic immunity, which means that the device should be able to work normally in a certain electromagnetic environment.

• EMI refers to electromagnetic interference, that is, the electromagnetic interference generated by the device itself cannot have too much impact on other electronic products.

In order to achieve these two goals, hardware engineers and software engineers were racking their brains and had to make many adjustments.

EMC is one of the most important indicators of product quality. The purpose of the test is to detect the impact of electromagnetic radiation generated by electrical products on the human body, power grids in public places, and other normally working electrical products.

EMC design and EMC testing complement each other. The quality of EMC design is measured by EMC testing. Only by predicting and evaluating EMC compatibility throughout the entire process of EMC design and development of products can we discover possible electromagnetic interference early and take necessary suppression and protection measures to ensure the electromagnetic compatibility of the system.

2. EMC Standards Release and Management

The three most authoritative international standardization organizations recognized by the world:

• IEC (International Electrotechnical Commission): It has several technical committees, among which the main ones engaged in EMC are CISPR (International Special Committee on Radio Interference), TC77 (Technical Committee 77) and other related technical committees.

• ISO (International Organization for Standardization): Founded in 1947, a non-governmental organization headquartered in Geneva, Switzerland. The main publisher of automotive electromagnetic compatibility standards.

• ITU (International Telecommunication Union): An intergovernmental organization headquartered in Geneva, Switzerland. Any sovereign state of the United Nations can become a member of the ITU.

The standard management and release unit of China is the National Standardization Administration (SAC) . IEC standards have been widely adopted by Europe, the United States, Japan, China and other regions and countries, playing an important role in eliminating international technical trade barriers and product conformity certification. For example, most of the content of GB/T17626.X introduced in this article refers to the international standard IEC61000-4-X series. Because the content involves the standards of foreign organizations, for copyright protection, the detailed content of these standards is not easy to obtain on the Internet. Friends in need can check the acquisition method at the end of the article.

3. GB/T 17626.X series of national standards

The national recommended standard "Electromagnetic Compatibility Test and Measurement Technology GB/T 17626" series, as of now, there are 27 current latest national standards GB/T 17626, of which "GB/T 17626.5-2019" was released on June 4, 2019, and will be implemented on January 1, 2020, replacing the old version of "GB/T 17626.5-2008". The current latest versions of the standards are as follows:

To view the latest standard number, go to

National Standards Information Public Service Platform :

http://std.samr.gov.cn/gb/gbQuery. Since this recommended standard adopts the standards of international organizations such as ISO and IEC, and involves copyright protection issues, the above platform does not provide online reading services. If you need a formal standard publication, please contact China Standards Publishing House, or see the method of downloading the pdf electronic version at the end of the article .

4. Selection of EMC test

The equipment should be subjected to all tests necessary for its reliability requirements, but from economic considerations, the test items should be reasonably limited to the minimum.

The test items that are suitable for your electronic device depend on several factors:

• Types of disturbance affecting equipment: magnetic field, electric field

• Environmental conditions: indoor, outdoor, temperature, humidity, etc.

• Required reliability and performance: household appliances, industrial control, automobile and military industries, etc.

• Economic constraints

• Equipment characteristics

Immunity testing can be applied to various stages of equipment, such as:

• R&D Test

• Type test

• Acceptance test

• Production test

If your product has a dedicated product standard, you should give priority to the dedicated standard before considering the general standard. The GB/T 17626 series of standards introduced in this article are general standards. For example, several EMC test standards for automotive electronics:

• GB/T 21437.3-2012 Electrical disturbances caused by conduction and coupling in road vehicles

• GB14023-2006 Radio disturbance characteristics of vehicles, ships and devices driven by internal combustion engines

• GB18655-2002 Limits and measurement methods for radio disturbance characteristics used to protect vehicle-mounted receivers

To find out which EMC tests your product should undergo, you can check GB/T 17626.1-2006 Electromagnetic compatibility test and measurement technology immunity test general introduction . The first part of the standard document briefly introduces the equipment types applicable to each test.

Although the GB/T 17626 series of standards includes 37 standards, the requirements for different products are also different. Some products only need to complete a few of the tests. Since each test involves a lot of content such as test concepts, test levels, test arrangements, test procedures, and test result analysis, this article only briefly describes several tests. For detailed introductions, please refer to the standard document content.

5. Electrostatic discharge immunity test

This test is to evaluate the performance of electronic equipment when subjected to electrostatic discharge. In addition, it also includes the electrostatic discharge that may occur from the human body to objects close to key equipment. It is mainly divided into contact discharge and air discharge.

Applicable equipment:

Applicable to all electronic equipment used in an environment where electrostatic discharge may occur, both direct and indirect discharge should be considered. Except for equipment used in an ESD controlled environment.

Test equipment:

• The electrostatic discharge generator, also known as the electrostatic gun, can generate static electricity of different voltage levels. Through two discharge electrodes, it can simulate air discharge and contact discharge.

Simple circuit diagram of static generator

Test level :

The coupling paths of static electricity mainly include contact discharge and air discharge:

• Contact discharge: Mainly for semi-finished electronic products, or electronic products with metal casings, which means the parts that can be touched by the human body. Using contact discharge on this part can simulate the situation where human body discharge causes damage to electronic products during production, transportation and use.

• Air discharge: a discharge method for plastic or metal shells coated with insulating paint. This discharge method does not use direct contact but uses high-voltage static pulses to break through the air and transmit to the inside of the product, causing damage to electronic products or components. When performing air discharge, the electrostatic gun discharges to the air for well-sealed products, but the product has good sealing and there is no static coupling loop, so the product will not be damaged. If the sealing is not good, it is easy to be damaged.

Test method:

The test layout for different equipment is also different. Before conducting the test, the test method must be determined:

• Whether the equipment under test is tested as a desktop device or a floor-standing device

• Determine the point of applied discharge on electronic equipment

• Whether contact discharge or air discharge is used at each point

• The number of discharges applied at each point

• Test level used

6. Surge (impact) immunity test

Surge voltage is mainly generated during lightning or power system switching. The surge impact test can be used to evaluate the equipment's immunity to surge voltage.

Applicable equipment:

Surge immunity testing is usually applicable to equipment connected to a network or grid outside a building.

Test equipment:

• Combination Wave Generator

• Coupling and Decoupling Networks

Test level:

Test method:

For different test lines, the coupling/decoupling network is also different.

7. Voltage fluctuation immunity test

This standard applies to electrical and/or electronic equipment with a rated current of not more than 16A per phase. It does not apply to electrical and electronic equipment connected to DC or 400Hz AC power distribution networks. Tests for equipment connected to these networks are given in other national standards. The immunity test levels and related performance criteria required in special electromagnetic environments are given in applicable products, product categories or general standards. However, many types of products are not sensitive to voltage fluctuations, so these devices do not need to be tested in this test.

Applicable equipment:

Usually, the amplitude of voltage fluctuation does not exceed 10%; therefore, many devices are not disturbed by voltage fluctuation. This test is suitable for devices that will be installed in areas where the power grid will produce large voltage fluctuations.

Test equipment:

• Waveform Generator

• Power Amplifier

Schematic diagram of voltage fluctuation test generator

Test level:

Test method:

The EUT shall be subjected to three voltage fluctuation tests in sequence for each selected test level and duration combination, with the minimum interval between voltage fluctuation sequences being twice 60s (see Figure 2). Each typical operating mode shall be tested. The test duration shall be determined by the standardization technical committee of the relevant product. For three-phase equipment, the three phases shall be tested simultaneously. The step voltage is applied phase by phase with the same phase angle, and the starting point of application is not simultaneous.

8. Electrical fast transient pulse group immunity test

The purpose of this test is to test the performance of the power supply port, signal, control and grounding port of electronic equipment when they are disturbed by electrical fast transients (pulse groups). This test is to couple a pulse group composed of many fast transient pulses to the power port of the electronic equipment or the control signal port. It is mainly to verify the immunity of electrical and electronic equipment to various types of transient disturbances such as those from switching transient processes (cutting off inductive loads, relay contact bounce, etc.).

Applicable equipment:

Applicable to electronic equipment connected to the power supply network or with cables (signal or control) close to the power supply line.

Test equipment:

• Pulse group generator: Generates fast transient pulse groups, with adjustable voltage peak, pulse group time and pulse group period.

• Coupling clamp: used to couple fast transient pulse group signals into the test circuit without electrical connection to the electronic equipment.

Test level:

As the name suggests, the interference signal applied is a pulse group, which has three main parameters:

• Pulse group duration

• Pulse group period

• Voltage peak

Test method:

9. Power frequency magnetic field immunity test

The purpose of this standard is to establish a common and reproducible basis for evaluating the performance of household, commercial, and industrial electrical and electronic equipment exposed to power frequency (continuous and short-term) magnetic fields.

Applicable equipment:

The power frequency magnetic field immunity test should be limited to equipment that is sensitive to magnetic fields (such as Hall effect devices, cathode ray tubes and special devices installed in strong magnetic field environments). Equipment used in small magnetic field environments may be excluded.

Test equipment:

• Current Source

• Induction coil

• Auxiliary test equipment

Test level:

The magnetic field test level is divided into stable continuous magnetic field test level and short-time test level, as shown in the following figure:

Test method:

The test environment conditions need to be carried out in accordance with the standard climate conditions of IEC60068-1:

• Temperature: 15℃~35℃;

• Relative humidity: 25%~75%;

• Atmospheric pressure: 86kPa~106kPa.

As we all know, the magnetic field is divided into three directions: X, Y, and Z. By adjusting the position of the coil, the device under test can receive magnetic field interference in the three-axis directions.

10. Damped oscillation magnetic field immunity test

The tests in this standard verify the immunity of equipment when it is subjected to a damped oscillatory magnetic field associated with its specific location and installation conditions (e.g. the proximity of the equipment to the source of disturbance). The damped oscillatory magnetic field is generated when the isolating switch is connected to the high-voltage busbar.

Applicable equipment:

The damped oscillatory magnetic field immunity test is mainly applicable to equipment installed in high voltage substations.

Test equipment:

• Generator for generating damped sinusoidal current

• Induction coil

Test level:

Different from the stable and unchanging magnetic field applied in the previous power frequency magnetic field test, as the name implies, the applied magnetic field is a damped oscillating magnetic field, and the test level parameter has only one magnetic field peak value.

Test method:

It is almost the same as the power frequency magnetic field test. The equipment under test also needs to receive magnetic field interference in three axis directions.

11. Ringing wave immunity test

Ringing wave (as shown in Figure 1) is a typical oscillatory transient phenomenon induced in low-voltage cables due to switching of electrical networks and reactive loads, power circuit faults, insulation breakdown or lightning strikes. Usually, this phenomenon occurs in power supply networks (high voltage, medium voltage, low voltage) and control and signal lines. Ringing wave represents an electromagnetic environment widely present in residential and industrial facilities, and is suitable for testing the immunity of equipment to the above-mentioned pulse phenomena with steep slope characteristics. These pulses, without the action of filters, have a rise time of 10ns to several hundred ns and a duration of 10us to 100us.

Applicable equipment:

The ring wave immunity test is applicable to equipment connected to the AC power grid.

Test equipment:

• Ring Wave Generator

Test level:

Test method:

Ringing wave interference signals can be applied to power ports, I/O ports, and communication ports for testing.

12. Download EMC national standard documents

20191123 Current GBT17626.X electromagnetic compatibility standard

download.eeworld.com.cn/detail/okhxyyo/620820

The latest current national standards query: National Standards Information Public Service Platform http://std.samr.gov.cn/gb/gbQuery

w494143467

It’s really detailed!

langtuodianzi

Very detailed graphic information!

Mr.QD

Awesome!