This section of IEC 61000 outlines the performance requirements, testing procedures, and classification processes for the protection against electromagnetic disturbances offered by unpopulated enclosures for frequencies ranging from 10 kHz to 40 GHz. The shielding effectiveness must be assessed before the installation of any internal electrical or electronic equipment and components. This measurement is conducted to confirm that the enclosure offers sufficient shielding to ensure the acceptable performance of the fully assembled units when tested against applicable IEC standards.
It is important to note that the satisfactory performance of an empty enclosure does not guarantee that the finished units will meet all EMC performance test standards for the operating equipment (refer to the discussion in Annex A).
The intent of this standard is to establish a consistent method for assessing the electromagnetic shielding performance of unoccupied mechanical enclosures, such as cabinets and subracks, and to provide a marking code that enables manufacturers to choose enclosures with a known ability to attenuate electromagnetic fields. When determining the applicability of this standard for specific equipment and applications, as well as the shielding requirements for the enclosures based on frequency, manufacturers must consider the immunity to various electromagnetic disturbances, including lightning and high-altitude electromagnetic pulse (HEMP).
The adoption of the classification system in this standard aims to promote consistency in describing the protection against electromagnetic stresses provided by the enclosure. This encompasses the protection of internal equipment from external electromagnetic stresses and the protection of external equipment from internally generated electromagnetic stresses.
Technical committees responsible for enclosures may decide on the scope and application of the classification system within their own standards and define “enclosure” as applicable to their equipment. However, the testing methods and performance categories must adhere to those specified in this standard. An informative guide for detailing the requirements in relevant enclosure product standards is provided in Annex B.
