Induced Current in Anti-Theft Ducts of Pole-mounted Distribution Transformers

This article analyses and presents an economic evaluation of the impact in load losses of anti-theft metal ducts (throats) in the low-voltage side of pole-mounted single phase distribution transformers. Anti-theft throats are used to cover the low voltage bushings to eliminate the possibility of an unwanted connection to the transformer terminals. The results presented are based on simulations, performed with a commercial finite element program, to quantify losses caused by currents induced in the anti-theft duct of a 167-kVA distribution transformer. The results show that when the antitheft throat is added: (i) The load losses are increased and (ii) the operation cost of the transformer is increased.