Notes Changed note Date. 1 (A) Changed template 09 / 07 / 2008

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2 Revisions Notes Changed note Date 1 (A) Changed template 09 / 07 / Changed template. Clause hot-rolled steel added. Clause , , , , , , and shall be thermally designed to resist the fault current of 40 ka 1 sec added. Clause nuts shall be locked with 2 punches, added. Clause revised added. 02 / 04 / /22

3 Contents 12.1 References Scope Definitions Description Ball coupling Socket coupling Clevis-Tongue fitting Yoke plate Turnbuckle Coupling bolt Power arc protection device Requirements General Marking Mechanical requirements Ball coupling Material Design Mechanical requirements Electrical requirements Socket coupling Material Design Mechanical requirements Electrical requirements Clevis - tongue coupling Material Design Mechanical requirements /22

4 Electrical requirements Yoke Plate Material Design Mechanical requirements Electrical requirements Turnbuckles Material Design Mechanical requirements Electrical requirements Coupling bolt Material Design Mechanical requirements Electrical requirements Power arc protection device Material Design Mechanical requirements Electrical requirements Type test General Dimensions Thickness of zinc coating Strength Fittings Yoke plate Arcing horn Fault current Corona Sample test General Dimensions Thickness of zinc coating Strength /22

5 12.8 Routine test Delivery General Documentation Assembly drawing List of material Manufacturing process Quality system Installation instructions Reports Transport and storing Installation Tables Table 1 Strength classes of fittings Table 2 Dimensions of clevis-tongue fittings Figures Figure 1 Dimensions of clevis-tongue fittings Figure 2 Yoke plate test load arrangement /22

6 12.1 References Note that standards, regulations etc. which are referred to in these guidelines are subject to continuous change and can be withdrawn, revised or replaced. It is the obligation that the contractor immediately will inform the client of such changes. IEC IEC SS SS-EN SS-EN SS-EN SS-EN SS-EN SS-EN ISO SS-EN ISO 1234 SS-EN ISO 1461 SS-EN ISO SS-EN ISO 9001 SS-EN ISO SS-IEC SS-ISO 272 SS-ISO Dimensions of clevis and tongue couplings of string insulator units Insulators for overhead lines with a nominal voltage above V- AC power arc tests on insulator sets Overhead line material - Clevis and tongue couplings, dimensions Metallic materials - Charpy impact test - Part 1: Test method Mechanical properties of fasteners - Part 2: Nuts with specified proof load values - Coarse thread Overhead electrical lines exceeding 45 kv (AC) Locking devices for ball and socket couplings of string insulator units - Dimensions and tests Insulators for overhead lines with a nominal voltage above V- Part 1: Ceramic or glass insulator units for a.c. systems - Definitions, test methods and acceptance criteria Mechanical properties of fasteners made of carbon steel and alloy steel -- Part 1: Bolts, screws and studs Split pins Hot dip galvanized coatings on fabricated iron and steel articles - Specifications and test methods Metallic materials - Brinell hardness test - Part 1: Test method (ISO :1999) Quality management systems - Requirements Fasteners Hot dip galvanized coatings (ISO 10684:2004) Dimensions of ball and socket couplings of string insulator units Fasteners -- Hexagon products -- Widths across flats ISO general purpose metric screw threads Tolerances - Part 4: Limits of sizes for hot-dip galvanized external 6/22

7 screw threads to mate with internal screw threads tapped with tolerance position H or G after galvanizing SS-ISO 2178 Non-magnetic coatings on magnetic substrates - Measurement of coating thickness - Magnetic method SS-ISO 3508 SS-ISO 5455 SvK TR 05-10E SvK TR 08E Thread run-outs for fasteners with thread in accordance with ISO 261 and ISO 262 Technical drawings - Scales Technical guidelines Insulator sets Technical guidelines Documentation 12.2 Scope These guidelines are applicable to fittings which are to be used in insulator sets according to SvK TR 05-10E for overhead lines and comprise design and testing. The intention of the specification is to guarantee satisfactory performance of the insulator fittings during the lifetime of the overhead line Definitions Technical terms and definitions used in these guidelines: Insulator set Device for insulating conductors either in suspension or tension. Insulator string The insulating part of the insulator set consisting of one or more insulators joined together. Highest voltage for equipment The highest phase-to-phase voltage for which the equipment is designed. The highest voltage for equipment is designated Um in this document. Corona extinction voltage The voltage where no corona is visible when the voltage is reduced from a level with visible corona. Fault current The greatest short duration current which is caused by either a short-circuit (I k ) or earth fault (3I 0 ) 7/22

8 12.4 Description Ball coupling Ball fittings for facilitating a connection to the socket on the cap side of disc insulators Socket coupling Socket fittings for facilitating a connection to the ball on the pin side of disc insulators Clevis-Tongue fitting Fittings with a clevis and tongue which can be connected by means of either a bolt or a pin Yoke plate Fitting for separating twin insulator strings and twin or triple conductors at a predetermined fixed distance Turnbuckle Fitting for adjusting the distance between the support and the insulator string or the insulator string and the conductor Coupling bolt Means of joining fittings with a clevis and tongue coupling Power arc protection device Fitting for the protection of insulator strings and conductors from power arcs and for distributing the electrical field Requirements General Fittings shall be able to withstand the mechanical stresses which can occur during transport, handling and installation at temperatures as low as 40 C, in addition to the mechanical stresses which can occur during the lifetime of the overhead line at temperatures from -50 C to +100 C Marking Fittings shall be marked with raised or indented/stamped characters with a minimum height of 3 mm as follows: Trademark of the manufacturer Type or catalogue number Insulator designation Bolts and nuts to be marked in accordance with SS-EN ISO och SS-EN /22

9 Year of manufacture Mechanical requirements Insulator fittings shall conform to the mechanical requirements of SS-EN When designing/dimensioning insulator fittings by means of stress calculations the following additional requirements shall be fulfilled. The combined stress (comb) of tension, bending and shear shall be less than the characteristic strength fuk at a load equivalent to Fuk in accordance with SS-EN 50341:11.6.SE.1.1. The combined stress (comb) of tension, bending and shear shall be less than the characteristic strength fyk at a load equivalent to 1.1 times the load Rd in accordance with SS-EN 50341:11.6.SE.1.1. The combined stress (comb) of tension, bending and shear shall be calculated according to the formula: x comb x y When testing fittings made from steel or aluminium permanent deformation due to tension, bending and shear stress may not occur at a load less than Fdef where: 2 y Fdef = 1,1 Rd Where Rd is the dimensioning load in the serviceability limit state in accordance with SS-EN 50341:11.6.SE.1.1. The breaking load (Fu) achieved during testing shall, for fittings made from steel and aluminium which have been statistically tested in accordance with SS-EN , exceed Fuk. The breaking load (Fu1) achieved during testing shall for other fittings exceed: Ful = 1,1 Fk Definitions F uk = The characteristic ultimate tensile strength given in regulations for the material concerned. fyk = The characteristic yield stress given in regulations for the material concerned. F def = Minimum required test deformation load F k = Specified minimum failing load F u = Achieved test breaking load F u1 = Achieved test breaking load R d = Dimensioning load in the serviceability limit state 9/22

10 Ball coupling Material Ball couplings shall be made from forged steel and be hot-dip galvanised. The thickness of the zinc layer shall conform to the requirements of SS-EN ISO 1461 Table 2 and 3. The impact strength of the forged steel shall be a minimum of 27 J at 0 C when tested in accordance with SS-EN The rupture strength Rm for test specimens taken from the manufactured part shall not exceed 700 MPa Design Balls on the end of pins shall conform to SS-IEC Attachments for arcing horns shall have two holes 14 mm diameter spaced at 32 mm centres. Other fittings shall be connected by either a tongue or a clevis coupling in accordance with Clause Mechanical requirements The ball coupling strength shall be equal to the minimum strength of the insulator string for which the ball coupling is intended and also conform to the requirements of regarding allowable stress. For deformation and failing loads see Table Electrical requirements Ball couplings shall be thermally designed to resist the fault current of 40 ka -1 sec. Welding shall not occur between contact surfaces when tested in accordance with Clause The peak value of the fault current shall be a minimum of 2,3 times the r.m.s value Socket coupling Material Socket couplings shall be made from forged steel or malleable iron and be hot-dip galvanised. The thickness of the zinc layer shall conform to the requirements of SS-EN ISO 1461 Table 2 and 3. The impact strength of the forged steel shall be a minimum of 27 J at 0 C when tested in accordance with SS-EN The rupture strength Rm for test specimens taken from the manufactured part shall not exceed 700 MPa Design Sockets shall conform to SS-IEC Size 16 mm shall be type 16A. Locking devices in accordance with SS-EN shall be used as retaining devices for ball couplings in sockets. Attachments for arcing horns shall have two holes 14 mm diameter spaced at 32 mm centres. Other fittings shall be connected by either a tongue or a clevis coupling in accordance with Clause /22

11 Mechanical requirements The socket coupling strength shall be equal to the minimum strength of the insulator string for which the socket coupling is intended and also conform to the requirements of regarding allowable stress. For deformation and failing loads see Table Electrical requirements Socket couplings shall be thermally designed to resist the fault current of 40 ka -1 sec. Welding shall not occur between contact surfaces when tested in accordance with Clause The peak value of the fault current shall be a minimum of 2,3 times the r.m.s. value Clevis - tongue coupling Material Clevis-tongue couplings shall be made from forged, hot-rolled steel or malleable iron and be hot-dip galvanised. The thickness of the zinc layer shall conform to the requirements of SS-EN ISO 1461 Table 2 and 3. The impact strength of the forged steel shall be a minimum of 27 J at 0 C when tested in accordance with SS-EN The rupture strength Rm for test specimens taken from the manufactured part shall not exceed 700 MPa Design Clevis-tongue couplings shall have dimensions as given in SS , IEC 60471, or Table 2 and Figure 1. Round holes for coupling bolts/pins shall be perfectly true with straight sides and through the whole coupling. The coupling shall be formed of one piece of materiel Mechanical requirements The clevis-tongue coupling strength shall be equal to the minimum strength of the insulator string for which the clevis-tongue coupling is intended and also conform to the requirements of regarding allowable stress. For deformation and failing loads see Ttable Electrical requirements The clevis-tongue couplings shall be thermally designed to resist the fault current of 40 ka -1 sec. Welding shall not occur between contact surfaces when tested in accordance with Clause The peak value of the fault current shall be a minimum of 2,3 times the r.m.s. value Yoke Plate Material Yoke plates shall be made from forged steel and be hot-dip galvanised. The thickness of the zinc layer shall conform to the requirements of SS-EN ISO 1461 Table 2 and 3. The impact strength of the forged steel shall be a minimum of 27 J at 0 C when tested in accordance with SS-EN The rupture strength Rm for test specimens taken from the manufactured part shall not exceed 700 MPa. 11/22

12 Design Yoke plates shall have coupling dimensions in accordance with SS , IEC 60471, or Table 2 and Figure 1. Round holes for coupling bolts/pins shall be perfectly true with straight sides. Yokes for insulator strings shall be so designed that the distance between the insulator sheds will be at least 100 mm. Yokes for twin and triple bundle conductors shall be so designed that the distance between sub-conductors will be 450 mm up to and including a conductor diameter of 32 mm and 600 mm for conductor diameter greater than 32 mm Mechanical requirements The strength of the yoke plate shall be equal to the minimum strength of the insulator string for which the yoke plate is intended and also conform to the requirements of regarding allowable stress. For deformation and failing loads, see Table Electrical requirements Yoke plates shall be thermally designed to resist the fault current of 40 ka -1 sec. Welding shall not occur between contact surfaces when tested in accordance with Clause The peak value of the fault current shall be a minimum of 2,3 times the r.m.s. value Turnbuckles Material Turnbuckles shall be made from forged steel and be hot-dip galvanised. The thickness of the zinc layer shall conform to the requirements of SS-EN ISO 1461 Table 2 and 3. The thickness of the zinc layer on threaded parts shall conform to the requirements of SS-ISO The impact strength of the forged steel shall be a minimum of 27 J at 0 C when tested in accordance with SS-EN The rupture strength Rm for test specimens taken from the manufactured part shall not exceed 700 MPa Design Turnbuckles shall have coupling dimensions in accordance with SS , IEC 60471, or Table 2 and Figure 1. Round holes for coupling bolts/pins shall be perfectly true with straight sides. Turnbuckles shall provide a minimum length adjustment of 150 mm. Adjustable parts shall be locked to prevent unwinding. Threaded parts shall be greased with corrosion protective grease Mechanical requirements The strength of the turnbuckle shall be equal to the minimum strength of the insulator string for which the turnbuckle is intended and also conform to the requirements of regarding allowable stress. For deformation and failing loads, see Table Electrical requirements Turnbuckles shall be thermally designed to resist the fault current of 40 ka -1 sec. The current density in threaded parts shall not exceed 70 A/mm 2. Welding shall not occur between contact surfaces when tested in accordance with Clause The peak value of the fault current shall be a minimum of 2,3 times the r.m.s. value. 12/22

13 Coupling bolt Material Coupling bolts shall be made from forged steel and be hot-dip galvanised. The thickness of the zinc layer shall conform to the requirements of SS-EN ISO 1461 Table 2 and 3. Split pins shall be made from austenitic stainless steel. The impact strength of coupling bolts made from forged steel shall be a minimum of 27 J at 0 C when tested in accordance with SS-EN Design The coupling for fittings shall consist of a bolt and nut. Fitting couplings shall be designed to have: A head with a minimum of two parallel flanges. A cylindrical smooth part for contact with the body of the tongue or clevis coupling. A section with metric threads for installation of the nut. If the nut is not provided with metallic locking a suitable size hole for a split pin should be provided. Threads shall be in accordance with SS-EN ISO with thread run-outs in accordance with SS-ISO Split pins shall be designed in accordance with SS-EN ISO The spanner to fit the head and nuts of fitting couplings shall have a width across flats in accordance with SS-ISO Mechanical requirements The strength of the coupling bolt shall be equal to the minimum strength of the coupling for which the turnbuckle is intended and shall also conform to the requirements of regarding allowable stress. For deformation and failing loads, see Table Electrical requirements Coupling bolts shall be thermally designed to resist the fault current of 40 ka 1 sec. Welding shall not occur between contact surfaces when tested in accordance with Clause The peak value of the fault current shall be a minimum of 2,3 times the r.m.s. value Power arc protection device Material Power arc protection devices shall be made from steel and be hot-dip galvanised. Should steel tubes be used for power arc protection devices, both the internal and external surfaces of the tubes shall be hot-dip galvanised. The thickness of the zinc layer shall for both external and internal surfaces conform to the requirements of SS- EN ISO 1461 Table 2 and Design It shall be possible to install power arc protection devices on assembled insulator sets. In addition they shall be so designed as to require a minimum of space on the supports. The attachment of arcing rings shall be on one side and be so designed that disc insulators of the insulator string are able to incline at an angle in accordance with SS-IEC Annex A without damaging the glass/porcelain portion of any insulator disc. 13/22

14 Attachment to fittings shall be one-sided and designed with two M12 bolts spaced at 32 mm centres. The bolts shall be attached to the power arc protection device in such a way that they are impossible to drop accidentally. Nuts shall be locked with two punches. Bolts shall conform to the requirements of property class 8.8 in accordance with SS ISO Nuts shall conform to the requirements of property class 8 in accordance with SS-EN and have a width across flats in accordance with SS-ISO 272. Welds connecting the attachment arm to the arc ring shall be complete penetration welds. A distance of 45 mm between the arcing ring and the insulator shead is desirable Mechanical requirements Power arc protection devices shall withstand a load of 1500 N, acting at an arbitrary point, without being deformed. Power arc protection devices subject to fault current shall not be deformed by their own dead weight Electrical requirements Fault current Power arc protection devices shall trap power arcs over the insulator string and divert them outwards. Power arc protection devices shall be thermally designed to resist the fault current of 40 ka 1 sec, with a current density not exceeding 80 A/mm 2. Welding shall not occur between the power arc protection devices contact surface and the fittings. The peak value of the fault current shall be a minimum of 2,3 times the r.m.s. value. Power arc protection devices shall conform to the requirements of IEC Clause 12.4 together with the additional test requirements that are specified in contained herein. Corona Power arc protection devices shall, in a complete insulator set, conform to the requirements of SvK TR 05-10E Clause Voltage distribution Power arc protection devices shall be so designed that the voltage distribution over the insulators is improved and that, in the case of an insulator string with disc insulators, the voltage does not exceed 20 kv over each individual insulator Type test General Unless otherwise agreed type tests shall be performed in accordance with Clauses on five test samples. The tests shall be conducted in such a way that neither the method nor the equipment affects the result. 14/22

15 Dimensions The intention of this test is to verify that the fittings fulfil the requirements in accordance with Clauses , , , , , and in addition to being in accordance with the manufacturers drawings regarding measurements Thickness of zinc coating The intention of this test is to verify that the fittings fulfil the zinc coating thickness requirements in accordance with Clauses , , , , , and The tests shall be performed in accordance with SS-ISO Each sample shall be subject to, depending on size, 3 to 10 measurements. The points of measurement shall be evenly and randomly distributed over the entire sample surface Strength Fittings The intention of this test is to verify that the fittings conform to the requirements of Clauses , , , , and The tests shall be performed in a tensile testing machine. Every test sample shall be subjected to the deformation load in accordance with Table 1 and be checked regarding permanent deformation. After all checks have been completed the load shall be increased until failure occurs. Fittings shall not have any permanent deformation when checked. Fittings shall fulfil the following requirements regarding failing load: Where X T SBK 1,2 * X T = Average value of the type test results T MFL = Specified minimum failing load T = Standard deviation for the type test results. In addition hardness shall be tested in accordance with SS-EN ISO Yoke plate The intention of this test is to verify that the yoke plate fulfils the requirements in accordance with Clause The test shall be performed in a tensile testing machine. For testing the test specimen shall be mounted in accordance with Figure 2. Every test specimen shall be subjected to the deformation load in accordance with Table 1 and be checked regarding permanent deformation. After all checks have been completed the load shall be increased until failure occurs and be checked regarding yielding. Yoke plates shall not have any permanent deformation when checked. Yoke plates shall withstand the specified failing load without collapsing. In addition hardness shall be tested in accordance with SS-EN ISO /22

16 Arcing horn The intention of this test is to verify that the arcing horn fulfils the requirements in accordance with Clause The test shall be performed in a tensile testing machine or with a dead weight. Each test specimen shall be subjected to a load of 1500 N, which shall be applied at the most unfavourable point, and be checked regarding deformation. Arcing horns shall not have any permanent deformation when checked Fault current The intention of this test is to establish the capability of fittings to withstand fault current. The fittings shall be tested when assembled in a suspension insulator set in accordance with SvK TR 05-10E. Testing shall be performed in accordance with IEC 61467, test series X, test circuit A. The test load shall be 3 kn. Fittings for the insulator set shall fulfil the requirements of IEC Clause 12.4 with the following additions and alterations which shall be performed after the conclusion of the test series: The zinc layer is not to be damaged The creepage distance is not to be reduced due to damaged disc or composite insulators. Exposure of white porcelain due to glaze scalds is not permitted on porcelain insulator discs. All disc or composite insulator units in the string tested shall be tested to verify that they fulfil the electromechanical failing load requirement for porcelain insulators, the mechanical failing load requirement for toughened glass insulators and the specified mechanical load requirement for composite insulators. All porcelain and toughened glass insulator units in the string tested shall be tested and shall pass a temperature cycling test in accordance with IEC All disc or composite insulators in the string tested shall be tested to verify that they fulfil the requirement for wet power frequency withstand voltage Corona The intention of this test is to verify the corona extinction voltage in a fully assembled insulator string. The test shall be performed in accordance with SvK TR 05-10E Clause /22

17 12.7 Sample test General Sample tests shall be carried out by the manufacturer on insulator fittings selected at random from the lot to be supplied. Test samples shall be supplied by the manufacturer free of charge to the client and shall not be included in the lot to be supplied. The size of the test samples are indicated in table below. Lot size Sample size N 300 Subject to agreement 300 < N < N < N The samples shall be subjected to testing in accordance with Clauses to Insulator fittings which have been submitted for test shall be discarded. The manufacturer shall inform the client when sample tests shall be performed. Records from the sample tests shall be filed by the manufacturer and be shown to the client on request. In the case where any component does not comply with the requirements, re-testing shall be performed as below. If only one fitting, or part thereof, fails to comply with the sample test requirement, a new sample equal to twice the quantity originally submitted for that test shall be subject to re-testing. The re-testing shall comprise the test or tests in which failure occurred. If two or more fittings, or parts thereof, fail to comply with any of the sample tests, or if any failure occurs during re-testing, the complete lot shall be considered not to comply with the requirements. Provided that the cause of the failure can be clearly identified, the manufacturer may sort the lot to eliminate all the fittings with this defect. The sorted lot shall then be resubmitted for sample testing. The number then selected shall be three times the first quantity chosen for the test. The re-testing shall comprise the test or tests in which failure occurred in the original test. If any fitting, or part thereof of the sorted lot, fails during this re-testing, the complete lot shall be considered as not complying with the requirements Dimensions This test shall be performed in accordance with Clause Thickness of zinc coating This test shall be performed in accordance with Clause /22

18 Strength This test shall be performed in accordance with Clause Routine test Fittings made of malleable iron shall be proof load tested. The tests shall be performed as a mechanical load test. A mechanical load of 50 % of the specified failing load shall be applied to the fitting. Fittings which show permanent deformation or cracks shall be discarded Delivery General The client shall, according to these guidelines, approve the fittings before delivery. For approval the manufacturer shall show that the fittings conform to these guidelines. The manufacturer shall provide documentation in accordance with Clauses to inclusive for approval. The approval of drawings by the client does not release the manufacturer from his obligations regarding the fittings complying with these guidelines. All documentation shall be written in Swedish or English Documentation General requirements for documentation see SvK TR 08E Assembly drawing Each assembly drawing shall have a minimum of two views at an appropriate scale in accordance with SS-ISO On each drawing shall be given: Type and/or catalogue number Principal dimensions The dimensions of the fitting with tolerances All marking Weight List of materials List of material Description of material in included parts Manufacturing process Description of the manufacturing process 18/22

19 Quality system Quality system in accordance with SS-EN ISO Installation instructions Installation instructions in Swedish or English with the required drawings Reports Reports in accordance with Clause Transport and storing The insulator set fittings shall be packed up in that way that they will not be damaged or fouled at transport, construction and storing Installation Installation shall be performed in accordance with the installation instructions. The power arc nuts shall be locked with two punches. 19/22

20 12.11 Tables Table 1 Strength classes of fittings Specified Deformation Insulator Breaking load Allprov load class Fuk Fuk1 kraft Fdef kn kn kn kn U ,5 U ,4 U ,6 U ,5 U ,5 2 * U ,0 2 * U ,1 Table 2 Dimensions of clevis-tongue fittings Breaking d e Bolt load a b c max min diameter kn mm mm mm mm mm mm , ,6 20/22

21 12.12 Figures Figure 1 Dimensions of clevis-tongue fittings Dimensions given in Table 2 e d a b d c d e d c 21/22

22 Figure 2 Yoke plate test load arrangement F Shackle Chain link Shackle F 22/22