What is BS EN 61000-4-21 - Electromagnetic compatibility about?
BS EN 61000 is a series on Electromagnetic compatibility (EMC). Electromagnetic compatibility is the ability of electrical equipment and systems to function acceptably in their electromagnetic environment, by limiting the unintentional generation, propagation and reception of electromagnetic energy which may cause unwanted effects such as electromagnetic interference (EMI) or even physical damage in operational equipment. BS EN 61000-4-21 considers tests of immunity and intentional or unintentional emissions for electric and/or electronic equipment and tests of screening effectiveness in reverberation chambers. BS EN 61000-4-21 establishes the required test procedures for performing such tests. Only radiated phenomena are considered.
The objective of BS EN 61000-4-21 is to establish a common reference for using reverberation chambers to evaluate the performance of electric and electronic equipment when subjected to radiofrequency electromagnetic fields and for determining the levels of radio-frequency radiation emitted from electric and electronic equipment. BS EN 61000-4-21 main aim is to give a general basic reference to all concerned product committees of the IEC. The product committees should select emission limits and test methods in consultation with CISPR. The product committees remain responsible for the appropriate choice of the immunity tests and the immunity test limits to be applied to their equipment.
Note: BS EN 61000-4-21 does not intend to specify the tests to be applied to a particular apparatus or system.
Who is BS EN 61000-4-21 - Electromagnetic compatibility for?
BS EN 61000-4-21 on Electromagnetic compatibility is useful for:
- Telecommunication component manufacturers
- Telecommunication equipment manufacturers
- Design engineers
- Quality control personnel
Why should you use BS EN 61000-4-21 - Electromagnetic compatibility?
The goal of Electromagnetic compatibility is the correct operation of different equipment in a common electromagnetic environment. It is also the name given to the associated branch of electrical engineering. Most electronic equipment is, in some manner, affected by electromagnetic radiation. Sources of radiation can be natural or man-made in origin and can be intentional or unintentional. Examples of intentional radiators are wireless and personal communication systems. Examples of unintentional radiators are welders, thyristors, high-speed data buses, fluorescent lights, switches operating inductive loads, etc.
Realistic environments for the propagation of electromagnetic waves are often characterized by multiple reflections and multipath effects. Reverberation chambers go some way to simulate such complex environments in an extreme manner (worst-case effect) and maybe more representative than other EMC test methods in this respect. An advantage of reverberation chambers as mentioned in BS EN 61000-4-21 is the ability to generate a statistically isotropic, homogeneous, unpolarized and uncorrelated interior field, through the action of the tuner/stirrer. High-level electromagnetic fields are easily and safely generated using reverberation chambers. The high-quality factor or “Q” of such chambers allows fairly high field strengths to be generated with relatively moderate input powers (resonant fields). The absence of an absorber makes the generation of high field levels safer as the risk of igniting absorbers is eliminated. Adequate screening of the enclosure confines the high fields to the interior of the chamber. Using BS EN 61000-4-21 you can specify tests of immunity and intentional or unintentional emissions for electric and/or electronic equipment and tests of screening effectiveness in reverberation chambers.
What’s changed since the last update?
BS EN 61000-4-21:2011 supersedes BS EN 61000-4-21:2003. BS EN 61000-4-21:2011 includes some technical changes with respect to BS EN 61000-4-21:2003. These include:
- In Clause 8, the use, and specifications of E-field probes for application to reverberation chambers have been added
- In Annex A, additional guidance, and clarifications on the use of reverberation chambers at relatively low frequencies of operation (i.e., close to the lowest usable frequency of a given chamber) are given, and its implications on the estimation of field uncertainty are outlined
- In Annex B, the symmetric location of the field probes when the chamber exhibits cylindrical symmetry has been disallowed, as such placement could otherwise yield a false indication of field uniformity and chamber performance at different locations
- Annexe C now contains more quantitative guidance on the setting of the maximum permissible stirring speeds that warrant quasi-static conditions of operation for chamber validation and testing
- In Annex D, a requirement for the EUT and equipment not to occupy more than 8 % of the total chamber volume in immunity testing has been added