1 General
1.1 Scope and object
This section of IEC 1000-2 is a technical report intended for guidance, not as a specification, for those who are in charge of writing immunity standards for an equipment or system. Its purpose is to classify electromagnetic environments and help improve the specification of the immunity requirements of an item containing electrical or electronic parts, and consequently obtain electromagnetic compatibility. It also gives basic guidance for the selection of immunity levels. The data are applicable to any equipment, subsystem or system making use of electromagnetic energy and operating in a specific location as defined by this report. The environment inside transportation equipment (vehicles, traction, ships, aircraft) is not described in this report, but their effect on the surrounding environment is included.
It should be noted that the immunity level requirements chosen for the items are not only inevitably bound to their environment, but also to the requirements of the applications (e.g. for reliability or safety purposes). That could lead to more stringent requirements than usual. These levels may also be established for more general purposes such as generic and product standards, taking into account statistical and economical aspects as well as common experiences in certain application fields.
1.2 Normative References
The following normative document contains provisions which, through reference in this text, constitute provisions of this section. At the time of publication, the edition indicated was valid. All normative documents are subject to revision and parties to agreements based on this section are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below.
GB/T 4365-1995 Terminology for Electromagnetic Compatibility (idt IEC 60050(61):1990)
1.3 Approach
Classification of the electromagnetic environment is based on the classification or a description of the electromagnetic phenomena prevailing at typical locations, not on existing test specifications. However, given a choice among equal possibilities, harmonization with existing test specifications (if appropriate) will simplify the situation and promote easier acceptance of the recommendations. The definition of electromagnetic environment in GB/T 4365 makes reference to "electromagnetic phenomena". The term disturbance degree is used in this report for quantifying the phenomena contributing to the electromagnetic environment, independently of any consideration of test levels. The term "severity level" will not be used in this report to describe the environment, as it is reserved for specifying immunity test levels in other IEC publications.
Thus, the concept and term of electromagnetic phenomenon is the starting point for defining the environment and selecting disturbance degrees in a classification document. Clauses 4, 5 and 6 of this report are the first step of the process. Three basic categories of phenomena have been identified: low-frequency phenomena, high-frequency phenomena and electrostatic discharge. In the first stage, attributes of the phenomena (amplitudes, waveforms, source impedance, frequency of occurrence, etc.) will be defined generically, and the expected range of disturbance degrees established. Then, in the second stage, ONE SINGLE value from that range has been identified as most representative for each phenomenon at a specific class of location and set forth as the compatibility level for that location class.
The process is illustrated in figure 1, showing how two sets of tables are used: a set of input tables that are phenomena-oriented and establish a range of disturbance degrees for a given phenomenon, and a set of output tables that are location-oriented and propose a table for each class, with one value of compatibility level for each of the phenomena identified in the set of input tables.
The final classification of environments into location classes and corresponding compatibility levels is discussed in clause 7, with specific examples of location classes given in the tables of annex A. The attributes of these location classes are based on the significant electromagnetic characteristics of a location, rather than geographical or structural aspects. For instance, the term "factory" is insufficient to categorize the location: in a factory, different localized conditions such as a computer room, general office space, as well as the manufacturing floor, proper, will be found.
The locations labels of the final classification imply specific definition of significant electromagnetic attributes. Classes of locations other than those listed in annex A may be identified and added to the set as the need arises.
It should be noted that this classification is based on environment data encountered circa 1990 with an acceptable probability factor. The disturbance degrees shown in annex A are offered as examples of compatibility levels for the guidance of product committees, not as normative permitted levels or immunity requirements. Those values are affected by uncertainties, and might not describe extreme environments.
Foreword i
IEC Foreword ii
IEC Introduction v
1 General
2 Definitions
3 User's Guide for this Report
4 Low-frequency Electromagnetic Phenomena
5 High-frequency Electromagnetic Phenomena
6 Electrostatic Discharge
7 Classification of Environments
8 Principles of the Selection of Immunity Levels
Annex A (Informative) Examples of Compatibility Levels for Typical Location Classes
Annex B (Informative) Radiated Oscillatory Disturbances
Annex C (Informative) Radiated Pulsed Disturbances
