什么是EMC风险评估?

欧洲 EMC指令(2014/30/EU) 2014年更新, replacing the old directive (2008/108/EC), and became mandatory from April 2016 for any new product entering the EU from that date onwards. 指令的变更旨在调整措辞和术语，以确保其与其他CE标志指令一致，并实施新立法框架(NLF)中列出的标准文本和模块。.

The principal objectives of the NLF were to:-

1. Provide legislation governing products that should be clear and more consistent across sectors
2. Clarify the obligations of all economic operators in the supply chain
3. Make provisions such that products are more traceable
4. Ensure that bodies that carry out conformity assessments should have certain attributes (e.g. independence and capability) and certain operational obligations
5. Ensure that each Member State shall have robust, 但比例, market surveillance and enforcement mechanisms in place based on a set of common requirements at the EU level.

As part of the changes that implement the above objectives, ‘risk’ was introduced into all the NLF-affected directives, 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.

What does ‘risk’ mean in the context of EMC?

EMC指令要求制造商“…应包括对风险的充分分析和评估…”，但由于EMC指令都是关于功能的，并且没有任何安全评估(包括电磁安全), 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.), what type of risks are being assessed?  

为了回答这个问题, it is first important to understand what a 风险分析 and risk assessment are. 风险分析是识别与产品及其使用环境相关的所有潜在电磁危害的过程. For each of the risks that have been identified, their impact has to be assessed (risk evaluation). The combination of the 风险分析 and evaluation is called the risk assessment.   

If, 作为这个过程的结果, 剩余风险很高, additional action is required to reduce the risk to a more acceptable level. 在后一个阶段，考虑来自其他来源的信息(例如im体育平台app下载出版物中的文章)和来自客户的反馈, 焦点小组等. forms the risk management as illustrated in diagram 1.

EMC risk assessment vs risk management

Diagram 1 - Risk Assessment v 风险管理

Many of the hazards identified in a risk assessment will be covered by the application of an applicable ‘harmonized standard’. However, it should be noted that not all hazards and hence risk will be covered in this process.

协调标准为标准涵盖的领域提供了对指令的“符合性推定”，但不能用于简单地证明产品将通过简单应用协调标准而不进行进一步分析来满足指令的要求.

Risk assessment example: Battery powered equipment

举个例子, 用于工业过程中加热炉温度记录的电池供电测试设备可以根据产品特定标准进行评估, En / iec 61326-1 Electrical equipment for measurement, 控制, and laboratory use — EMC requirements — Part 1: General requirements.

本标准包含在80MHz以上频率范围内的故意发射机和ISM设备的辐射RF场存在下评估产品功能的测试(EN/IEC 61000-4-3)。. 它还定义了评估RF发射器和低于80MHz(低至150kHz)的ISM设备的测试要求，并使用标准EN/IEC 61000-4-6.

问题是EN/IEC 61000-4-6是作为一种传导评估来执行的，因为80MHz以下的波长非常长，传导比辐射更重要.

Does that mean that a manufacturer can simply ignore the test and all frequencies below 80MHz? 简而言之，没有.

风险识别将(应该)识别这样一个事实，即27MHz是用于材料处理的ISM频率，并且用作许多射频加热应用的基本频率. 如果只进行标准中包含的测试，就会知道会产生一个明显的电磁场，但没有评估. 制造商将识别这种危险，并通过执行额外的测试来减轻风险，以补充协调标准中定义的测试, thus ensuring that the residual risk is low.

The above is just one example of where the application of a harmonized standard alone is not suitable for demonstrating EMC合规 with the EMC Directive – there will be many more, based on the type and use of the product.

风险评估示例:平板电脑

下面是另一个例子, a tablet PC can be used in an environment other than the classic ‘domestic, 商业和轻工业”. Given that a manufacturer needs to think about both the use and also foreseen misuse (part of the 风险分析), it is certainly expected that this type of product will be used on a train, 一辆车, or in much closer proximity to a cellular device than the product-specific standard (CISPR 35 / EN55035)预计. 高功率发射器与产品的近距离接触导致产品暴露于比标准覆盖更高水平的电磁辐射. All these situations are foreseen and should be covered in the risk assessment.

大多数传导排放标准从150kHz开始，但是在这个频率以下产生的电气噪声越来越多. 电动汽车充电器, 光伏装置逆变器, and the like all use switching technologies in the low kHz region and produce potentially significant EM emissions. 由于兼容性水平未知(这是一个与标准本体相关的问题)，很少有EMC标准要求在150kHz以下进行测试，但会产生大量噪声，并且标准中缺乏抗扰度测试来降低风险.

It is important for EM hazards to be considered as part of the overall risk assessment of the product. 与安全相关的社区非常熟悉与安全相关的风险评估，通常是基于广泛选择的不同重点的人. EM knowledge unfortunately is not normally well-represented meaning that EMC safety risks are often overlooked.

Before any 电磁兼容测试 is performed, it should be considered in parallel with the EM safety aspects. 电磁兼容测试 for functionality would require the product to be operating in its normal mode(s) whereas 电磁安全测试 would require a different set of parameters to be assessed (such as a product with an electronic power switch, switching ‘on’ when it should be ‘off’) which would require the standby mode to be assessed as well.

结论

制造商需要确保执行电磁风险分析和电磁风险评估，作为遵守EMC指令的一部分. The EMC risk assessment needs to be documented and includes the justification that leads to the overall residual risk.

只有统一标准中包含的测试才提供了对其所涵盖参数的符合性假设，制造商应补充其整体风险管理，以确保识别和相应地评估其他危害.

EMC风险服务

风险评估不能从制造商那里分包出去，因为总体风险总是由制造商承担. 然而，了解电磁危害以及如何减轻这些风险是可以外包的事情，在将产品推向市场的产品实现阶段，无论由谁来做，都应该被视为整体风险评估的一部分.

If you would like specialist support to ensure that you meet all of your EMC obligations, please im体育APP.