Transformer turns ratio (TTR) equipment has been specifically designed to conduct TTR testing. These tests are able to verify the operating principle of a power transformer, and identify any shorted turns or open-circuited conditions. With a low voltage AC test, transformer turns ratio equipment measures the ratio of high voltage to all other winding at no-load. A TTR device then displays measured ratio variations, which should fall within 0.5% of the nameplate markings. Values that fall outside of this range indicate a shorted or open transformer winding.