Abstract
THE Vista is a periodical published by the British Porcelain Co., Ltd., London, S.W.1, and deals mainly with subjects of interest to the electric power industry. In the May number it concludes a series of articles on insulator manufacture. Each piece of electrical porcelain is carefully inspected by factory inspectors immediately after removal from the kiln, and all pieces failing to pass this inspection are destroyed. To find the porosity, fragments of the porcelain are placed in fuchsine dye and subjected to a pressure of two thousand pounds per square inch for twenty-four hours. They are then removed, carefully dried, and broken to find out whether there is ‘‘penetration or not. If any is noticed, the representative batch of insulators is destroyed. The thermal test consists in immersing the porcelain in boiling water and then in iced water for periods of ten minutes, one hot and one cold test constituting a thermal cycle. After five such cycles, the porcelain is flashed over to test for thermal failure. After further thermal cycles, the insulators are subjected to a flashover test. They are next subjected to a flashover test at a frequency of 250,000 cycles per second. This test has proved a boon to the industry, as it eliminates porcelain with dielectric defects. In assembling the insulators, Portland cement with a definite proportion of pure water is used. They are allowed to stand five days before being cleaned and treated with weather-proofing compound, and after three more days a routine tension test is applied. The final tests are made in the presence of the ‘customers inspector, who sees the large completed insulator subjected to a load of 10,000 lb. weight and to a high-frequency flashover.
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Manufacture of Insulators. Nature 130, 199–200 (1932). https://doi.org/10.1038/130199d0
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DOI: https://doi.org/10.1038/130199d0