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Insulator crossarms for 345-kv EHV transmission line have been developed and tested. They use four solid-core post insulator columns (quadruped type) or two solid-core post insulator columns and two disc insulator strings (Twin-arm type) to form a tetrapod mounted horizontally from the tower. They are characterized by making possible narrower right-of-way, more compact tower dimension, and supporting higher mechanical load.
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Kimoto et al. (1971) studied this question.
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