BS 62772:2016 pdf download – Composite hollow core station post insulators for substations with a.c. voltage greater than 1 000 V and d.c. voltage greater than 1 500 V — Definitions, test methods and acceptance criteria

BS 62772:2016 pdf download – Composite hollow core station post insulators for substations with a.c. voltage greater than 1 000 V and d.c. voltage greater than 1 500 V — Definitions, test methods and acceptance criteria 8.3 Assembled core load tests 8.3.1 Test for the verification of the maximum design cantilever load (MDCL) NOTE MDCL is considered to be equal with 1 ,25 times MML as determined by the type test as determined in IEC 61 462:2007, Clause 8. 8.3.1 .1 Test procedure The test can be performed without a filler or the filler may be removed after the test and before the dye penetration test. One insulator with the smallest outer tube diameter and the smallest wall thickness and one insulator with the largest outer tube diameter and the smallest wall thickness made on the production line using the standard end fittings shall be selected. The overall length of the insulators shall be at least 8 times the outer diameter of the tube, unless the manufacturer does not have facilities to make such a length. In this case, the length of insulator shall be as near as possible to the prescribed length range. The base end-fitting has to be fixed rigidly. The insulators shall be gradually loaded to 1 ,1 times the MDCL rating at a temperature of 20 °C ± 1 0 K and held for 96 h. The load shall be applied to the insulators at the conductor position, perpendicular to the direction of the conductor, and perpendicular to the core of the insulators. At 24 h, 48 h, 72 h and 96 h, the deflection of the insulators at the point of application of the load shall be recorded, as additional information. After removal of the load, the steps below shall be followed: • visually inspect the base end fitting for cracks or permanent deformation, • check that threads of the end fitting are re-usable, • if required, measure the residual deflection. Cut each insulator 90° to the axis of the core and about 50 mm from the junction of the tube to the end fitting, then cut the base end fitting part of the insulator longitudinally into two halves in the plane of the previously applied cantilever load. The cut surfaces shall be smoothed by means of fine abrasive cloth (grain size 1 80). • Visually inspect the cut halves for cracks and delaminations, •...