The Vanguard Instruments ATRT-03 S2 is the third generation, microprocessor-based, automatic, three phase, transformer turns-ratio tester. This light weight, rugged, portable unit is designed for transformer testing at utility power substations.

The ATRT-03 S2 determines the transformer turns ratio using the measurement method. The ATRT-03 S2 outputs an excitation test voltage to the transformer primary windings. The induced secondary voltage is sensed and the transformer turns ratio is calculated. The ATRT-03 S2 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 ATRT-03 S2 to detect and test 130 transformer types defined by .