IEC 60120 pdf – Ball and socket couplings of string insulator units – Dimensions
The object of this international standard is to define the dimensions of a series of standardball and socket couplings using the standard locking devices (see IEC 60372) in order topermit the assembly of insulators or metal fittings supplied by different manufacturers.
This document applies to string insulator units of the cap and pin and long rod types and theirassociated metal fittings.
For the pin ball and the socket,dimensions apply to the finished product after any surfacetreatment.
Extreme positions of the pin ball in the socket are given in Annex A.
Typical examples of gauges for checking the dimensions of pin balls and sockets are given inAnnex B.
NOTEOnly the dimensions necessary for assembly are dealt with in this standard. Properties of materialandworking loads are not specified. The co-ordination of dimensions with strength classes is specified in lIEC 60305and lEC 60433.
The following documents are referred to in the text in such a way that some or all of theircontent constitutes requirements of this document. For dated references,only the editioncited applies.For undated references, the latest edition of the referenced document (including
any amendments) applies.
IEC 60050-471:2007,International Electrotechnical Vocabulary (IEV) – Part 471: Insulators
IEC 60372,Locking devices for ball and socket couplingsof string insulator units-Dimensions and tests
3Terms and definitions
For the purposes of this document,the terms and definitions of lEC 60050-471, some ofwhich are reproduced below for ease of reference, apply.
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ball and socket coupling
coupling consisting of a ball, a socket and a locking device, and providing flexibility
[SOURCE: IEC 60050-471:2007,471-03-11]
string insulator unit
cap and pin insulator or long rod insulator of which end fitting are suitable for flexibleattachment to other similar insulator units or to connecting accessories
[SOURCE: IEC 60050-471:2007,471-03-08]
4Designated size of coupling
This document includes eight standard ball and socket couplings designated by the nominalpin diameters in millimetres.Each designated size of coupling is defined by the dimensions of
the pin ball, of the socket, of the hook-on “GO” gauge, of the lower part of the insulator and ofthe corresponding locking device.
NOTEDimensions of twin-balled pins for coupling of two sockets are stated in Clause 13. Dimensions of the holefor the locking devices are stated in Clause 14 and Clause 15.
The pin ball shall conform to the dimensions specified in Clause 10. The main dimensions
goverming the shape of the pin ball are h , d2 nand r .Dimensiogr is given for guidancebecause its accurate value ‘may be obtained only by the drawing. in addition,the shank
diameter d, must not exceed the specified values within a length equal to H3 of thecorresponding worn hook-on “Go” gauge (see Clause 12).
The socket interior shall conform to the dimensions specified in Clause 11, which alsospecifies the thickness of the locking device.
The 16 mm designated size of coupling according to Clause 11 includes two alternativesockets. There is only one type of pin ball fit for it, but the corresponding locking deviceshould be used. That is,the 16A socket should be matched with the 16A locking device,the16B socket should be matched with the 16B locking device.
NOTE Sockets according to the clause mentioned are shown with flat bottoms， Sockets with rounded bottoms withradi of curvature not less than the dimensions r2 of the pin balls can also be used. In this case, the dimensions Rshave to be correspondingly decreased.
7Hook-on “Go” gauge
The external dimensions of the socket have not been laid down.However，the socket shallpermit acceptance of the hook-on “Go” gauge according to Clause 12.
Lower part of the insulator
The shape of the lower part of the insulator shall be such that assembly with the socket ofmaximum external dimensions according to Clause 7 will always be possible.