什么是EMC风险评估?

欧洲 EMC指令(2014/30/EU) 2014年更新, 取代旧指令(2008/108/EC), 并从2016年4月起强制要求任何从该日起进入欧盟的新产品. The change of directive was aimed at aligning the wording and terminology to ensure it was consistent with other CE标志 directives and implement standard text and modules laid out in the New Legislation Framework (NLF).

民族解放阵线的主要目标是:-

1. 制定监管产品的立法，使产品在各个部门之间更加明确和一致
2. 明确供应链中所有经济经营者的义务
3. 制定规定，使产品更易于追溯
4. 确保进行合格评定的机构应具有某些属性(例如.g. 独立性和能力)和某些操作义务
5. 确保每个会员国都有健全的, 但比例, 在欧盟层面建立基于一套共同要求的市场监督和执行机制.

作为实现上述目标的变更的一部分, 所有受nlf影响的指令都引入了“风险”一词, 包括 EMC指令协调标准.

Risk however has multiple meanings within the directive ranging from risks associated with the product (which is the responsibility of the manufacturer); to products that present a risk which is the responsibility of the market enforcement agencies and actions required by actors in the supply chain where risks have been identified.

在EMC环境中，“风险”是什么意思?

The EMC Directive requires that manufacturers ‘…shall include an adequate analysis and assessment of the risk(s)…’ but since the EMC directive is all about functionality and does not have any assessment of safety (including electromagnetic safety, 哪些是由其他覆盖的 CE标志 指令，例如 低压指令(LVD)、机械安全; 医疗器械指令(MDD)等.)，评估何种类型的风险?  

为了回答这个问题, 首先了解什么是风险分析和风险评估是很重要的. Risk analysis is the process of identifying all of the potential EM hazards associated with both the product and the environment in which it is going to be used. 对于已确定的每一个风险，必须评估它们的影响(风险评估)。. 风险分析和评价的结合称为风险评估.   

If, 作为这个过程的结果, 剩余风险很高, 需要采取额外的行动将风险降低到更可接受的水平. This latter stage and considering information from other sources (文章 in industry publications for example) and feedback from customers, 焦点小组等. 形成如图1所示的风险管理.

EMC风险评估与风险管理

图1 -风险评估与风险管理

在风险评估中确定的许多危害将被适用的“协调标准”所涵盖。. 然而，应该指出的是，并不是所有的危害，因此风险将涵盖在这个过程中.

A harmonized standard provides a ‘presumption of conformity’ to the directive for areas that the standard covers but cannot be used to simply justify that the product will meet the requirements of the directive by a simple application of the harmonized standard without further analysis.

风险评估示例:电池供电设备

举个例子, battery-powered test equipment used for the logging of temperatures in a heating furnace in an industrial process may be assessed against the product-specific standard, En / iec 61326-1 测量用电气设备, 控制, 和实验室用。电磁兼容要求。第1部分:一般要求.

This standard contains tests to assess the functionality of the product in the presence of radiated RF fields from intentional transmitters and ISM devices in the frequency range above 80MHz (EN/IEC 61000-4-3). It also defines test requirements for the assessment of RF transmitters and ISM devices below 80MHz (down to 150kHz) and uses the standard EN/IEC 61000-4-6 for this.

The problem is that EN/IEC 61000-4-6 is performed as a conducted assessment since the wavelengths below 80MHz are very long and conduction predominates over radiation.

这是否意味着制造商可以简单地忽略测试和所有低于80MHz的频率? 简而言之，没有.

The risk identification would (should) identify the fact that 27MHz is a well-used ISM frequency for the treatment of material and is used as the fundamental frequency for many RF heating applications. It will be known that there will be a significant EM field generated and yet there is no assessment if only the tests contained in the standard are performed. The manufacturer would identify this hazard and mitigate the risk by performing additional tests to supplement those defined in the harmonized standard, 从而确保剩余风险低.

以上只是单独应用协调标准不适合演示的一个例子 EMC合规 EMC指令-根据产品的类型和用途，还会有更多.

风险评估示例:平板电脑

下面是另一个例子, 平板电脑可以在传统的“家庭”以外的环境中使用, 商业和轻工业”. 考虑到制造商需要考虑使用和可预见的误用(风险分析的一部分), 当然，这种类型的产品将在火车上使用, 一辆车, 或者比产品特定标准更接近蜂窝设备(CISPR 35 / EN55035)预计. The close proximity of higher power transmitters to products results in the product being exposed to higher levels of EM radiation than the standard covers. 所有这些情况都是可预见的，并应在风险评估中予以涵盖.

Most conducted emissions standards start from 150kHz however there is an increasing amount of electrical noise generated below this frequency. 电动汽车充电器, 光伏装置逆变器, 诸如此类的都在低千赫区域使用开关技术，并产生潜在的显著电磁辐射. Very few EMC standards require testing below 150kHz due to the unknown compatibility levels (this is a standard body-related issue) but there is significant noise being generated and a lack of immunity tests in the standards to mitigate the risks.

将电磁危害作为产品整体风险评估的一部分是很重要的. The safety-related community is very familiar with safety-related risk assessments and is normally based on a wide selection of people with differing focuses. 不幸的是，EMC知识通常没有得到很好的体现，这意味着EMC安全风险经常被忽视.

在执行任何EMC测试之前，应将其与EM安全方面同时考虑. 功能的EMC测试要求产品在其正常模式下运行，而 电磁安全测试 是否需要评估一组不同的参数(例如带有电子电源开关的产品), 当它应该“关闭”的时候却打开了)，这也需要评估待机模式.

结论

Manufacturers need to ensure that an EM 风险分析 and electromagnetic risk assessment is performed as part of complying with the EMC Directive. 需要记录EMC风险评估，并包括导致总体剩余风险的理由.

Only the tests contained in harmonized standards provide a presumption of conformity for the parameters that they cover and a manufacturer should supplement these with their overall risk management to ensure that other hazards are identified and assessed accordingly.

EMC风险服务

Risk assessments are not something that can be subcontracted out from a manufacturer since the overall risk always has to lie with them. Understanding EM hazards and how to mitigate these risks however is something that can be outsourced and irrespective of who does it should be considered as part of the overall risk assessment during the product realization phase of bringing a product to market.

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