Energy-saving principle of variable frequency speed regulation energy-saving device

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Energy-saving principle of variable frequency speed regulation energy-saving device [Copy link]

1. Frequency conversion energy saving

From fluid mechanics, we know that P (power) = Q (flow) ╳ H (pressure), flow Q is proportional to the first power of speed N, pressure H is proportional to the square of speed N, power P is proportional to the cube of speed N. If the efficiency of the water pump is constant, when the flow rate is required to decrease, the speed N can decrease proportionally, and at this time the shaft output power P decreases in a cubic relationship. That is, the power consumption of the water pump motor is approximately in a cubic ratio with the speed. For example: the power of a water pump motor is 55KW. When the speed drops to 4/5 of the original speed, its power consumption is 28.16KW, saving 48.8% of electricity. When the speed drops to 1/2 of the original speed, its power consumption is 6.875KW, saving 87.5%.

2. Power factor compensation energy saving

reactive power not only increases line loss and heating of equipment, but more importantly, the reduction of power factor leads to the reduction of active power of the power grid. A large amount of reactive power is consumed in the line, the equipment is inefficient and wasteful. According to the formula P=S╳COSФ, Q=S╳SINФ, where S is apparent power, P is active power, Q is reactive power, and COSФ is power factor, it can be seen that the larger the COSФ, the larger the active power P. The power factor of ordinary water pump motor is between 0.6-0.7. After using the frequency conversion speed regulation device, due to the effect of the internal filter capacitor of the frequency converter, COSФ≈1, thereby reducing reactive loss and increasing the active power of the power grid.

3. Soft start energy saving

Since the motor is directly started or Y/D started, the starting current is equal to (4-7) times the rated current, which will cause serious impact on the electromechanical equipment and the power supply network, and will also require too high a capacity of the power grid. The large current generated during startup and the vibration will cause great damage to the baffle and valve, which is extremely detrimental to the service life of the equipment and pipelines. After using the frequency conversion energy saving device, the soft start function of the frequency converter will make the starting current start from zero, and the maximum value will not exceed the rated current, which reduces the impact on the power grid and the requirements for power supply capacity, and extends the service life of the equipment and valves. Save equipment maintenance costs.