LNRYC pressure differential controller is a high-precision electronic micro-pressure differential automatic sensing device specially developed for mechanical positive pressure supply air system. It is suitable for front room, joint front room, stair room and other areas. The product adopts four-wire 485 bus connection method. All pressure differential controllers in each pressure differential control system unit are connected in parallel to the wind valve control box by four conductors with a cross-sectional area of not less than 1.5mm² (two power lines and two signal lines). During system operation, the pressure differential controller detects the current residual pressure value in the area in real time, and controls the opening and closing of the bypass relief valve in the positive pressure supply air system through the wind valve control box, and controls the residual pressure value in the corresponding area within a reasonable range.