The Performance of Electronics under Sand and Dust Test in a Sand and Dust Chamber

Electronic products mainly include lighting products, electronic components, mobile communication terminals, and have clear requirements for external shell protection tests, such as mechanical protection, waterproof, explosion-proof, water-conflict, etc. At present, sand and dust test is not taken seriously. The general view is that the source of dust in other regions is extremely diverse. Such as fine sand from deserts, carbonaceous materials come from vehicle exhaust or artificial.

Dust damage in real life is huge, and itself can deteriorate into harmful substances, such as interference optical performance, activity components stuck, reduce thermal conductivity efficiency, wear active components, block air filter, electric insulation harm, etc. If the conditions mature, it can lead to mildew, corrosion, and may even cause fire. The diagnosis of the current dust test equipment is not enough. Whether there is dust test in the JJG/JJF documents, can it be required to calibrate, and what are the parameters of calibration? From the analysis, the current calculation calibration and test regulations have not formulated corresponding standards. The main reference basis is GB/T2423.37-2006’Environmental Test Methods of Electric and Electronic Products, Part 2: Test Method Test L: Sand and Dust Test‘, and corresponding calibration measures can be consulted with local technical institutions and manufacturers of environmental test equipment.

It can be seen that there is no uniform standard for the current measurement guidance documents, which will bring trouble to the testers in determining the corresponding parameters. Different manufacturers have different measuring methods, which makes it difficult to guarantee the value of test parameters. Below is roughly summarized and sorted out the facilities used in sand and dust test, and the standards formulated by them, and also referring to the standards of other countries, obtaining reference sources and finding effective protection strategies for the design of dust-proof products, and giving suggestions.

LISUN SC-015 Sand and Dust Chamber is applied to physical and other related performance tests for electronic and electrical products, lamps, electrical cabinets, electrical components, automobiles, motorcycles and their parts and other products under simulated dust climate conditions. After the measurement, it is judged whether the performance of the product meets the requirements through verification, so as to facilitate the design, improvement, verification and factory inspection of the product. Comply meets IEC60529:1989 +A1:1999 +A2: 2013 <Degrees of protection provided by enclosures (IP Code)>,IEC60598-1,  GB2423.37-89 (Test L: dust test methods), GB4208, GB/T 4942.2-93(protective casing grade of low-voltage apparatus), GB7000.1 <Luminaires Part 1: General Requirements and Tests> 9.2.1, 9.2.2 and Figure 6, DIN40050 and IP5K0. The dust test chamber is applicable to the IP5X and IP6X dustproof test of the products.

Dust test chamber

1. Standards related to sand and dust tests
As mentioned above, sand and dust test is highly referenced standards at this stage, which are the same as IEC60068-2-68:1994 “Environmental Tests Part 2: Test Method Test L: Dust and Sand (English version). The MIL-STD-810f Sand and Dust in the U.S. Military Standard are almost the same, requiring many IP protection systems. The most frequently used code in the world is IP code, which is the same as GB4208 “Casing Protection Grade (IP Code)”. JISC0920:2003 “Casing Provided Protection Grade (IP Code)” of Japan is a complete borrowing of international standards. The requirements for dust tests must be consistent with IP5X and IP6X in the IP code. IP5X and IP6X indicate dust-proof and dust-proof respectively. IP5X can enter a small amount of dust, but cannot produce harmful accumulation; IP5X can be used with negative pressure or without negative pressure. IP6X must be negative pressure, and no dust can enter. For example, if a certain kind of photoelectric encoder is tested for dust, after the IP6X test, there is a slight influx of dust, indicating that it cannot meet the requirements of IP6X; then, according to the IP5X evaluation, it is found that the dark lines of the coding disk are blocked, and the product cannot pass the IP5X and IP6X tests.

The National Electrical Manufacturers Association (NEMA) series of standards are mainly borrowed from the Caribbean region and North America. Compared with IEC60529, various factors are applicable to NEMA250. It is not only necessary to pay attention to dust factors, but also to take into account factors such as mold, explosion-proof, steam, condensation, etc. Normally, the IP code is a guaranty that meets the MEMA requirements, otherwise it would not be possible. Taking NEMA250 as an example, the symbols of 12K, 12, 6P, 6, 5, 4X, 4, 3S, 3 meet the dust-proof requirements and meet the requirements of IP5X. The codes are 12K, 12, 5, 4X, 4, 3S, 3. GB/T4942.2-1993 and GB/T4942.1-2006 can meet the standards of dust prevention for vehicle products. The test method for dust prevention test is mainly IP6X and IP5X. From the “Definitions, Test Methods and General Performance Requirements (Automotive Parts) of Automobiles Wire Harness Connectors Part 1”, QC/T417.1-2001 clearly points out 4.21 dust test; GB/T10485-2007 clearly specifies sand and dust test in the 10th item of “External Lighting and Optical Signal Devices of Road Vehicles Durability in Environment”; German Standard DIN40050-9 “Road Vehicle (IP International Protection)-Protection Type Electric Equipment Resistance to External Substances, Water and Contact” Regulation on IPKX and IPKX are also made. Section 10 of GB7000.1-2007 “General Requirements and Test Methods of Lighting Fixtures” clearly states the requirements for dust prevention. By comparing the above standards, they are mostly divided into dust prevention and dust-proof. The following will compare the differences between GB/T2423.37 and Japanese Industrial Standard JISD0207 and GJB150.12A.

2. Dust test equipment and test requirements
In the above, the specifications of dust test have been described in detail. At present, generally speaking, the sand and dust chamber meets the requirements of the experiment. According to the relevant regulations of national standards, and search for relevant materials, one test equipment is not enough to meet the above requirements. According to preliminary estimates, the minimum requirements for testing are five sets of equipment. The specific requirements for testing should be referred to the standard. The requirements for the dust test are mainly the following parameters: test temperature, test relative humidity, dust concentration, wind speed, box volume, sand and dust types and particles diameter, test sample location, dust raising time and rest time and total test time, etc. When conducting the experiment, it is necessary to measure the temperature and humidity at that time, which all need certain restraint, which will not be described in detail in this paper. The test equipment used in IP5X and IP6X tests can satisfy the requirements of the test as long as it can be exhausted.

3. Protective measures for dust prevention
Using a strict closed structure, such as lock holes on external control devices of sand and dust chamber, assembly dust covers. Movable device ports, plug in dust plugs. Install filters, sand screens and other filters at the place of air vents to filter the dust better. Try to avoid using forced air-cooled devices and change the form of blowing to extraction. As for the circuit device used under bad conditions, a layer of protective material should be applied to its surface to ensure the safety of circuits.

4. Conclusion
In order to make the quality of domestic products more competitive in the international market, we need to solve some practical problems from small aspects, stabilize every step, so as to ensure that enterprises can develop better in the long run.

Lisun Instruments Limited was found by LISUN GROUP in 2003. LISUN quality system has been strictly certified by ISO9001:2015. As a CIE Membership, LISUN products are designed based on CIE, IEC and other international or national standards. All products passed CE certificate and authenticated by the third party lab.

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