Tree Tech Model TI
The Tree Tech Model TI Temperature Indicator is a microprocessor  based electronic device for remote supervision of temperatures of power transformers and reactors. The TI is capable of displaying up to 5 temperatures such as: insulating oil temperature plus the temperatures of three (3) windings in the same transformer, or the temperatures of the phases A, B, C, and spare transformer of a bank of single phase transformers.
 
The five temperature indications are differentiated through LED's on the TI front panel, which signal the temperature being measured. The highest temperature of all five will be continuously displayed, unless another temperature is selected through the keys up or down. After 5 seconds of inactivity, the display automatically returns to the highest temperature.