This International Standard applies to composite hollow core station post insulators consisting of a load-bearing insulating tube (core) made of resin impregnated fibres, insulating filler material (solid, liquid, gaseous pressurized or unpressurized), a housing (outside the insulating tube) made of polymeric material (for example silicone or ethylene-propylene) and fixing devices at the ends of the insulating tube. Composite hollow core station post insulators as defined in this standard are intended for general use in substations in both, outdoor and indoor environments, operating with a rated AC voltage greater than 1 000 V a.c. and a frequency not greater than 100 Hz or for use in direct current systems with a rated voltage greater than 1 500 V.d.c. The object of this standard is: to define the terms used; to prescribe test methods; to prescribe acceptance criteria. All the tests in this standard, apart from the thermal-mechanical test, are performed at normal ambient temperature. This standard does not prescribe tests that are characteristic of the apparatus of which the composite hollow core station post insulator ultimately may form a part (e.g. disconnector switch, reactor support, HVDC valves).