It is highly essential to monitor & control its Oil & Winding temperatures. Closely monitoring & keeping a check on these temperatures also prevents accidental breakdowns of these transformers. Oil / winding temperature indicators indicate temperature proportional to input resistance. The temperature is indicated on a 7 segments LED display TEST' mode allows the display to be varied from 0 to 150 C by varying the Test Control Potentiometer. In the Normal mode, 3 wires coming from the potentiometer on the local OTI/WTI (Min, Wiper, Max) are connected to the ROTI/RWTI along with the Auxiliary Supply. 'Zero Adjust' and 'Full-Scale Adjust' Potentiometers on the front panel allow for calibrating the ROTI/RWTI in the field