For glass and porcelain, the tests described include routine sampling of raw materials and physical tests on fired or moulded pieces, such as measurement of cross-breaking strength on small porcelain rods. Porcelain cap-and-pin bodies are usually tested routinely for electrical puncture strength and resistance to hydraulic bursting, while hollow shells are electrically puncture-tested only. Simple 'ring ing' impact tests are made on porcelain components of multiple-cone posts, to detect cracks. Polymeric insulators are not easy to test non-destructively although many types are proof-pulled, as are porcelain discs and long rods, both to reject weak pieces and to 'set' conical joints.

Inspec keywords: crack detection; nondestructive testing; polymer insulators; raw materials; insulator testing; porcelain insulators

Other keywords: raw material; polymeric insulator testing; cross-breaking strength; electrical puncture strength; porcelain cap-and-pin body; crack detection; nondestructive testing; small porcelain rods; hydraulic bursting

Subjects: Power line supports, insulators and connectors