Problem: In order to achieve HACCP (Hazard Analysis Critical Control Point) compliance, factories are investigating various measures for maintaining cleanliness in the food factory. Despite extensive cleaning, dust and other contaminants still enter the factory. Use positive pressurization indoors to prevent external air entering the space and also eliminate humidity, thereby keeping the indoor area clean. • Detect the differential pressure between the indoor space and external air, and use fan rotation (air flow) to control and stabilize the positive pressurization indoors. • Connect the E8Y Differential Pressure Sensor’s output (4 to 20 mA) to the E5AR, and connect the E5AR’s control output of 4 to 20mA to the Inverter. • Use high-speed control to control the high level of external interference (workers entering/exiting).