The Vanguard ATRT-03 S2 Automatic Three-phase Transformer Turns Ratio Tester determines the transformer turns ratio using the IEEE C57.12.90 measurement method. The Vanguard ATRT-03 S2 Automatic Three Phase Transformer Turns Ratio Tester outputs an excitation test voltage to the transformer primary windings. The induced secondary voltage is sensed and the transformer turns ratio is calculated.

The Vanguard ATRT-03 S2 Automatic Three Phase Transformer Turns Ratio Tester is capable of measuring turns ratios from 0.8 to 15,000. The transformer turns-ratio, excitation current, and phase angle readings are displayed on the large LCD. The automatic transformer type detection feature allows the Vanguard ATRT-03 S2 Automatic Three Phase Transformer Turns Ratio Tester to detect and test 130 transformer types defined by ANSI, CEI/IEC.