Yantai Yu-cable plant has its own deep well water supply system. It is supplied by a deep well pump with a rated flow rate of 30M3 / H and a lift of 120M. Previous work was as follows: pumping groundwater to 300M3 reservoirs and then two additional pressurized pumps to supply water directly to the whole factory and living area. In the living area also set up a high 28M, the capacity of 80M3 water tower water and regulator with. Since last year, the water table has significantly increased its groundwater level from -20M to -8M. Deep well pump water supply from the original 30M3 / H, into 40M3 / H, the entire system in the state of large flow low lift, water supply is much larger than the demand. To change this work, reduce energy consumption, the factory decided to transform the water supply system. According to the original design of the original pump is designed according to the deep well pump, the current water level is high, the load of this pump is light, it can be regarded as the fan pump load, so we decided to use fan inverter for frequency conversion Transformation. Feasibility analysis of transformation: According to the working characteristic of the pump, the flow Q of the pump is proportional to the motor speed N; the head H is proportional to the square of the motor speed N; and the pump power P is proportional to the cube of the motor speed N. Therefore, we can achieve the purpose of changing the pump flow and lift by controlling the speed of the pump motor. In the transformation, we decided to keep the remote pressure gauge according to the site situation. As the pressure control detection sensor at the water outlet, the pressure gauge can display the water pressure on the scene, meanwhile the change of the pressure can be transmitted to the control part of the inverter with the change of 0-5V voltage. By comparing the set pressure with the feedback pressure PI calculation, inverter control of the pump to achieve water requirements. After the transformation, the factory made a comparison before and after the transformation: the working current of the pump was about 80A (actual power 40KW) before the transformation. After the transformation, the working current was reduced to about 50A (actual power 25KW), and the reactive power consumption of the motor was reduced by 15KW , Significant energy saving, estimated savings of 136,800 degrees per year, saving 96,000 yuan, and achieved significant economic benefits, the plant since September 16, 2000 transformation completed, up to now the normal work has been more than 4 years, Electricity savings of nearly 40 million. Manufacturers are particularly satisfied with this