TURA-03 series turn ratio meters can test turns ratio by making only a one-time connection to transformers and automatically test all phases. TURA-03 series turn ratio testers can make automatic vector group detection and calculate ratio error. Tura-03 series turn ratio testers are very easy to use with the 7-inch display and user-friendly interface. https://www.hightest.co.uk/product-cat/three-phase-ttr//