China's motor power consumption accounts for 60% to 70% of the national power generation, fan, pump equipment annual electricity consumption accounts for 1/3 of the national electricity consumption. The main reasons for this situation are as follows: The traditional speed regulation method of fans, pumps and other equipment is to adjust the air supply and water supply by adjusting the baffle and valve opening of the inlet or outlet, and the output power consumes a large amount of energy in the baffle , The valve closure process. Because the fans and pumps mostly are square torque loads, the relationship between shaft power and speed is square, so when the fan and pump speed drop, the power consumption is also greatly reduced, so the energy saving potential is very large. The most effective energy saving measure is to use frequency conversion Governor to regulate the flow, air volume, frequency converter energy saving rate of 20% to 50%, and usually in the design, the user pump motor design capacity is much higher than the actual need, there is the phenomenon of "big car" , Inefficient, resulting in a lot of waste of electricity. Therefore, the promotion of exchange frequency control device is significant. Driven by a drive with a high energy-saving space. At present, many countries have designated the flow pressure control must use the frequency control device to replace the traditional way, China's State Energy Law Article 29, paragraph 2 also clearly stipulates that the fan pump load should adopt power electronic speed control. Frequency energy-saving energy-saving energy-saving device principle 1, frequency conversion energy-saving Fluid mechanics shows that P (power) = Q (flow) ╳ H (pressure), flow Q and speed N is proportional to the first power, pressure H and speed N Is proportional to the power P and the rotational speed of the cube is proportional to N, if the pump efficiency is constant, when the demand for regulating the flow rate down, the rotational speed N can be proportional to the decline, while the axial output power P cubic relationship between the decline. That is, the power consumption of the pump motor and the rotational speed of the approximate square ratio relationship. For example: a pump motor power 55KW, when the speed dropped to 4/5 of the original speed, the power consumption of 28.16KW, saving 48.8%, when the speed dropped to the original speed of 1/2, the power consumption The amount of 6.875KW, power 87.5%. 2, power factor compensation Energy-saving reactive power not only increases line loss and equipment heating, more importantly, the power factor reduction led to the reduction of active power grid, a large amount of reactive energy consumption in Line, the equipment is inefficient, serious waste, from the formula P = S╳COSФ, Q = S╳SINФ, which S-apparent power, P-active power, Q-reactive power, COSФ-power factor, we can see COSФ The larger the active power P, the average power factor of the pump motor is between 0.6-0.7. After using the VFD, COSФ ≈ 1 due to the filter capacitor inside the inverter, thus reducing the reactive power loss and increasing The active power grid. 3, soft-start energy-saving As the motor is started directly or Y / D start, the start current is equal to (4-7) times the rated current, this will have a serious impact on the mechanical and electrical equipment and power grid, but also the grid capacity requirements too high , Start-up generated when the current and vibration of the baffle and valve damage great, the equipment, the life of the pipeline is extremely unfavorable. The use of inverter energy-saving device, the use of inverter soft-start function will start the current from zero, the maximum does not exceed the rated current, reducing the impact on the power grid and the power supply requirements, extending the use of equipment and valves life. Save the equipment maintenance costs.
