A temperature indicator of power transformer is specially designed for protection of transformer in addition to its temperature indication and cooling control features. That means, this device performs three functions. These instruments indicate instantaneous temperature of oil and windings of transformer   They are commonly referred to in the industry as Oil Temperature Indicators (OTI) and Winding Temperature Indicators (WTI). Electrical utilities often utilize oil and winding temperature indicators to provide alarm and control signals that are used to activate cooling control systems on a transformer. Maintaining proper cooling controls can also extend the lifetime of the transformer past the typical life expectancy.   How to choose the suitable model oil temperature monitoring? 1. Whether the temperature of the measured object needs to be recorded, alerted and automatically controlled, and whether remote measurement and transmission are required; 2, the size and accuracy of the temperature range requirements; 3. Whether the size of temperature measuring element is appropriate; 4. When the temperature of the measured object changes with time, whether the hysteresis of the temperature measuring element can adapt to the temperature measuring requirements; 5. Whether the environmental conditions of the tested object damage the temperature measuring element; 6. Is it convenient to use?