The compensative column-type AC automatic voltage regulators can be divided into single phase TNDZ type (DBW type) ones and three phase (SBW type) ones. Compared with other types of voltage regulators, it enjoys a much larger capacity, higher efficiency and more stability when it comes to voltage regulation. It is also suitable for a wider variety of loads and can withstand instantaneous overload and long-tome continuous operation. It is equipped with functions such as overvoltage protection and short circuit protection, and can be easily installed and smoothly operated.