BS EN IEC 60305:2021 pdf download – Insulators for overhead lines with a nominal voltage above 1 000 V – Ceramic or glass insulator units for AC systems – Characteristics of insulator units of the cap and pin type.
1 Scope This International Standard applies to string insulator units of the cap and pin type with insulating parts of ceramic material or glass, intended for AC overhead lines with a nominal voltage greater than 1 000 V and a frequency not greater than 1 00 Hz. It also applies to insulators of similar design used in substations. This document applies to string insulator units of the cap and pin type either with ball and socket couplings or with clevis and tongue couplings. This document applies to string insulator units for use on overhead lines in clean areas and polluted areas. For use in areas characterized by very heavy pollution levels and for other particular or extreme environmental conditions, it may be necessary for certain dimensions to be changed and insulator units having different creepage distances, spacing and forms may be preferred (for example, flat profile, hemispherical etc.). Insulators for use on DC systems may also need different dimensions. In any case, it is applicable that the standardized mechanical characteristics of this document and coupling sizes are retained. The object of this document is to prescribe specified values for the mechanical characteristics and for the main dimensions of string insulator units of the cap and pin type. The power frequency, lightning impulse and puncture withstand voltages of string insulator units are not specified in this document. IEC 60383-1 gives the electrical characteristics which define string insulator units; their values are agreed between purchaser and manufacturer. Ball and socket couplings are covered by IEC 601 20, clevis and tongue couplings by IEC 60471 . NOTE For the definition of site pollution severity see IEC TS 6081 5-1 . 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)
4 Mechanical characteristics, dimensions and types String insulator units of the cap and pin type are standardized by the following specified characteristics: – Specified electromechanical or mechanical failing load (SFL) according to IEC 60383-1 ; – maximum nominal diameter of the insulating part; – nominal spacing; – minimum nominal creepage distance; – standard coupling. The corresponding values are indicated in Table 1 , Table 2, Table 3, Table 4 and Table 5. NOTE 1 The following points merit attention for insulators for use in polluted areas: a) even if the creepage distance is the same, the withstand voltage characteristics may change with shed shape of the insulators; b) even if the string length is the same, the withstand voltage characteristics may decrease with increasing insulator strength due to the lower efficiency of creepage distance for a larger average diameter. NOTE 2 IEC 6081 5 gives details on the important parameters of shed profiles for antipollution insulators. 5 Designation and marking with respect to shed profile Insulators are designated in Table 1 , Table 2, Table 3, Table 4 and Table 5 by the letter U followed by a number indicating the specified electromechanical or mechanical failing load in kilonewtons. The letter B or C which follows specifies a ball and socket or clevis and tongue, respectively. The following letter S or L, if present, specifies a short or long spacing. The letter P, D, V, or T present for “anti-fog” profile, “aerodynamic” profile, “two-alternating” profile, or “three-alternating” profile, as shown in Figure 1 , Figure 2, Figure 3,Figure 4 and Figure 5, respectively. IEC 60383-1 specifies that insulators shall be marked with the specified electromechanical or mechanical failing load. This load may be indicated by using the first part of the designation given in the first column of Table 1 , Table 2, Table 3, Table 4 and Table 5: For instance, the insulator may be marked U 1 60 for the units U 1 60 BS, U 1 60 BL and U 1 60 BLP.