The safe operation and service life of power transformers largely depend on the safety and reliability of transformer windings. The winding temperature exceeds the insulation withstand temperature and the insulation is destroyed, which is one of the main reasons that the transformer can not work normally. LD-TSID100 series dry transformer condition quantity monitoring device (referred to as monitoring device) is a kind of intelligent device specially designed for the safe operation of dry transformer according to the Technical Specification of Dry transformer Condition Quantity Monitoring Device of China Southern Power Grid.