How effective is the frequency converter?
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Dear all**, it is true that using frequency converters can help save energy, but under what conditions does this savings occur, and by how much? The rated frequency is 50 Hz. By how much does the power decrease for each 1 Hz drop, and how is this calculated? Could you let me know? Thank you! ! !
Variable frequency drives can generally be used in pumps for liquids, gases, etc. Energy can be saved when the amounts of gas and liquid used are not fixed. Theoretically, I don’t know how to calculate the energy savings specifically. If you are purchasing a large frequency converter, you can discuss it with the equipment manufacturer; they should be aware of this. Based on specific measurements taken on our production line, for every 1 Hz decrease in frequency, energy savings of around 1.7% can be achieved. This data is likely related to many factors such as the inverter model and the status of the production line; moreover, the reproducibility of the measurement data is poor, so it is for reference only.
It can only be calculated based on the load’s characteristic curve; the key is to consider the conditions of the load
It achieves the best energy-saving effects in centrifugal fans and water pumps. As for exactly how much energy is saved, it was explained clearly upstairs.
We’ll use it again, but I don’t understand. I want to know whether an inverter changes the frequency. Why does changing the frequency help save energy? I heard from the electricians here that it seems to be the voltage that is changed, but I think that’s not right; it should be the frequency that is changed, judging from its name
An inverter is certainly used to change the frequency in order to regulate the speed of an AC motor. However, when the frequency decreases, the output voltage (r.m.s.) also needs to be changed accordingly. In fact, at the output of the inverter, only the current is approximately sinusoidal, while the voltage is a rectangular pulse waveform with varying widths.
There is a linear relationship between frequency and speed, while there seems to be a cubic relationship between speed and power; therefore, the faster the speed decreases, the more significant the energy-saving effect. This approach is generally used in high-power motors where the load varies significantly, such as in applications involving flow rates or mixing
Generally speaking, as long as your load is fluctuating, using an inverter helps save energy. If your load does not fluctuate, it is your responsibility to determine the exact load level and select equipment and motors with the appropriate power rating.
It still isn’t clear. How is it calculated? As mentioned above, for every 1 Hz decrease, the power drops by 1.7%. So, if there is a 5 Hz decrease, does that mean a drop of 5*1.7=8.5%? So, 8.5% of a 30KW motor is 30*8.5% = 2.55KW, right?
9# gongweihua For pumps: rotational speed is directly proportional to flow rate. It is proportional to the square of the head. It is proportional to the cube of the power. You can calculate it by yourself. For example, if the frequency drops to 90%, the power becomes three times 90%, meaning the power is only 73% of the original value.
The power-saving rate varies depending on the type of load, and the specific values depend on the different device manufacturers.