IEC 60433:2021 pdf download

IEC 60433:2021 pdf download.Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic insulators for AC systems
1 Scope
This International Standard is applicable to string insulator units of the long rod type with insulating parts of ceramic material intended for use in AC overhead power lines with a nominal voltage greater than 1 000 V and a frequency not greater than 100 Hz. It is also applicable to insulators of similar design, used in substations. This document is applicable to ceramic string insulator units of the long rod type, either with a clevis end fitting at both ends for coupling with a tongue, or with a socket end fitting at both ends for coupling with a pin ball. The object of this document is to prescribe specified values for electrical and mechanical characteristics, and for the principal dimensions of ceramic string insulator units of the long rod type. This document is applicable to string insulator units for use on overhead lines situated in lightly polluted areas, and the creepage distances given in Table 1 have been established accordingly, using the IEC TS 60815-2 recommendation of 27,8 mm/kV for SPS class. However, shorter creepage distances are applicable for use in some non-polluted areas. If specific operating conditions require or allow non-standard (longer or shorter) creepage distances, the mechanical characteristics as well as the lengths L (see Clause 4) of this document are intended to be used unless the need for exceptionally long creepage distances requires values of L greater than those given in Table 1. In the case of special requirements, e.g. very heavy polluted areas and for other particular or extreme environmental conditions, it may be necessary for certain dimensions to be changed. As far as reasonably applicable, this document is also applicable to be applied to similar insulator units outside the scope of this standard, such as insulators for electric traction lines. This document does not include tests on insulators and dimensions of end fittings. Ball and socket couplings are covered by IEC 60120, clevis and tongue couplings by IEC 60471.
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 60383-1, Insulators for overhead lines with a nominal voltage above 1 000 V – Part 1: Ceramic or glass insulator units for AC systems – Definitions, test methods and acceptance criteria
4 Characteristics, dimensions and type of long rod insulators
String insulator units of the long rod type are characterised by the following specified characteristics:
– the standard lightning impulse withstand voltage (see IEC 60071 -1);
– the wet power frequency withstand voltage (see IEC 60071 -1);
– the tensile mechanical failing load;
– the maximum nominal length L of the insulator;
– the maximum nominal diameter D of the insulating part;
– the minimum nominal creepage distance;
– the standard coupling.
The corresponding values are specified in Table 1. The minimum nominal creepage distances are based on a unified specific creepage distance of 27,8 mm/kV for the lowest value of the highest voltage for equipment corresponding to the specified value of the standard lightning impulse withstand (in accordance with IEC 60071 -1). NOTE 1 The tolerances given in IEC 60383-1 are applicable to all the dimensions in Table 1, even if the adjectives “minimum” or “maximum” are used before the term “nominal”. NOTE 2 Dry lightning impulse withstand voltage and wet power frequency withstand voltage are specified in Table 1 for single unit string insulators. Values of withstand voltages of insulator strings consisting of more than one unit are not contained in this document. NOTE 3 The rod diameter is not specified since it depends on the mechanical characteristics of the insulating material. Information on the definition and classification of ceramic insulating materials can be found in IEC 60672-1 and IEC 60672-3. NOTE 4 Examples of shed profile are given in Clause 8, “Choice of profile” of IEC TS 60815-2:2008.
5 Designation and marking
Long rod insulators are designated in Table 1 by the letter L, followed by a figure indicating the specified mechanical failing load in kilonewtons. Then follows the letter B or C indicating socket or clevis coupling respectively, followed by the value of the lightning impulse withstand voltage in kilovolts.