Specification for radio disturbance and immunity measuring apparatus and methods – Part 4-3: Uncertainties@ statistics and limit modelling – Statistical considerations in the determination of EMC compliance of mass-produced products (Edition 2.0)
This part of CISPR 16 deals with statistical considerations in the determination of EMC compliance of mass-produced products. The reasons for such statistical considerations are:a) that the abatement of interference aims that the majority of the appliances to be approved shall not cause interference;b) that the CISPR limits should be suitable for the purpose of type approval of mass-produced appliances as well as approval of single-produced appliances;c) that to ensure compliance of mass-produced appliances with the CISPR limits@ statistical techniques have to be applied;d) that it is important for international trade that the limits shall be interpreted in the same way in every country;e) that the National Committees of the IEC which collaborate in the work of the CISPR should seek to secure the agreement of the competent authorities in their countries.Therefore@ this part of CISPR 16 specifies requirements and provides guidance based on statistical techniques. EMC compliance of mass-produced appliances should be based on the application of statistical techniques that must reassure the consumer@ with an 80 % degree of confidence@ that 80 % of the appliances of a type being investigated comply with the emission or immunity requirements. Clause 4 gives some general requirements for this so-called 80 %/80 % rule. Clause 5 gives more specific requirements for the application of the 80 %/80 % rule to emission tests. Clause 6 gives guidance on the application of the CISPR 80 %/80 % rule to immunity tests. The 80 %/80 % rule protects the consumer from non-compliant appliances@ but it says hardly anything about the probability that a batch of appliances from which the sample has been taken will be accepted. This acceptance probability is very important to the manufacturer. In Annex A@ more information is given on acceptance probability (manufacturer??s risk).