The ATRT-03 determines the transformer turns-ratio using the IEEE C57.12.90 measurement method. The transformer turns-ratio (ranging from 0.8 to 15,000) is determined by precisely measuring the voltages across the unloaded transformer windings. To ensure accuracy, the ATRT-03’s measuring circuitry self-calibrates before each measurement. It requires neither adjustment nor temperature compensation. The ATRT-03’s turns-ratio measurement accuracy is 0.1% or better.