IEC 60071-2-2018 pdf free
IEC 60071-2-2018 pdf free.Insulation co-ordination – Part 2: Application guidelines.
This document covers phase-to-earth, phase-to-phase and longitudinal insulation.
This document is not intended to deal with routine tests. These are to be specified by the relevant product committees.
The content of this document strictly follows the flow chart of the insulation co-ordination process presented in Figure 1 of IEC 60071-1:2006. Clauses 4 to 7 correspond to the squares in this flow chart and give detailed information on the concepts governing the insulation coordination process which leads to the establishment of the required withstand levels.
This document emphasizes the necessity of considering, at the very beginning, all origins, all classes and all types of voltage stresses in service irrespective of the range of highest voltage for equipment. Only at the end of the process, when the selection of the standard withstand voltages takes place, does the principle of covering a particular service voltage stress by a standard withstand voltage apply. Also, at this final step, this document refers to the correlation made in IEC 60071-1 between the standard insulation levels and the highest voltage for equipment.
The annexes contain examples and detailed information which explain or support the concepts described in the main text, and the basic analytical techniques used.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
IEC 60060-1:2010, High-voltage test techniques — Part 1: General definitions and test requirements
IEC 60071-1:2006, Insulation co-ordination — Part 1: Definitions, principles and rules IEC 60071-1:2006/AMD1:2010
IEC 60505:2011, Evaluation and qualification of electrical insulation systems
IEC TS 60815-1, Selection and dimensioning of high-voltage insulators intended for use in polluted conditions — Part 1: Definitions, in formation and genera! principles
ISO 2533:1975, Standard Atmosphere
3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
4 Representative voltage stresses in service
4.1 Origin and classification of voltage stresses
In IEC 60071-1, the voltage stresses are classified by suitable parameters such as the duration of the power-frequency voltage or the shape of an overvoltage according to their effect on the insulation or on the protection device. The voltage stresses within these classes have several origins:
— continuous (power-frequency) voltages: they originate from the system operation under normal operating conditions:
— temporary overvoltages: they can originate from faults, switching operations such as load rejection, resonance conditions. non-linearities (ferroresonances) or by a combination of these:
— slow-front overvoltages: they can originate from faults, switching operations or direct lightning strokes to the conductors of overhead lines:
— fast-front overvoltages: they can originate from switching operations, lightning strokes or faults;
— very-fast-front overvoltages: they can originate from faults or switching operations in gas- insulated substations (GIS);
— combined overvoltages: they may have any origin mentioned above. They occur between the phases of a system (phase-to-phase), or on the same phase between separated parts of a system (longitudinal).
All the preceding overvoltage stresses, except combined overvoltages, are discussed as separate Items under 4.3. CombIned overvoltages are discussed where appropriate within one or more of these items.
In all classifications of voltage stresses, transference through transformers should be taken into account (see Annex D).
In general, all classes of overvoltages may exist in both voltage ranges I and II (see IEC 60071-1). However, experience has shown that certain voltage classifications are of more critical importance in a particular voltage range: this will be dealt with in this document. In any case, it should be noted that the best knowledge of the stresses (peak values and shapes) is obtained with detailed studies employing adequate models for the system and for the characteristics of the overvoltage limiting devices.IEC 60071-2 pdf free download.
