TNS series three phases high precision automatic voltage regulator is combined with TND(SVC) single phase high precisiorautomatic voltage regulator, Three phases adjust individually to guarantee steady safe voltage in per phase, The incoming powerof network is three phases four wires system, starlike (Y) connection, the output power can be made in three phases four wires oithree phases three wires ,three ampere meters indicate the output current per phase, lesting the outine vollage of per phase by aswitch & a voltage meter shift.