This series of products consists of de-energized tap-changers designed for oil-immersed de-energized voltage regulating transformers. They are characterized by a vertical cage structure and are installed in a bell type configuration. These tap-changers have broad applications in power, rectifier, and electric furnace transformers with rated frequencies of 50Hz and 60Hz, rated voltages of 35kV, 66kV, and 110kV, and rated currents ranging from 125A to 2000A. It is essential to operate these tap-changers only when the transformer is de-energized.