TSDdifferential temperature controller has twothermo-bulbs to sense the differential temperature. After comparing the differential temperature with the setting value, thedifferential temperaturecontroller will putout a differential signal to make the temperature controller work.The differential temperature controllercan keep a constant value of differential temperature between two medium in general ventilation and some cooling devices. The two relativethermo-bulbs, one is fortemperature reference, the other one is for controlling signals.Differential temperature is directly controlled parameters.