Raytech TR-SPY Mark II is a Fully Automatic Three Phase Transformer Turns-Ratio Meter. It is a rugged, lightweight instrument that automatically measures Turns Ratio, Voltage Ratio, Excitation Current, Phase Relationship, and Phase Displacement. This fully automatic instrument can perform precision laboratory measurements as well as function extremely well in the field for routine maintenance testing. A single hook-up to the transformer is all that is needed to run a complete series of tests because all connections of various transformer configurations are accomplished internally. The TR-SPY Mark II system does not require and charts or calculations for testing. The system can test more combinations of transformer configurations than any other system making it the most versatile and easiest to use system available. The TR-SPY Mark II tests one of the widest ratio ranges available (0.8 to 13,000) and has the highest accuracy of any Automatic Three Phase Ratiometer (0.08%). This system can operate in a continuous mode allowing measurements of tap changers various positions. The TR-SPY is extremely easy to use and operate and will work on all configurations of single and multiphase transformers.