Precautions for the application of variable freque

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Notes on the application of variable frequency speed regulation of water pumps

introduction: variable frequency speed regulation is widely used in the energy conservation of pumps and fans, but in practical application, due to poor consideration of the factors affecting its energy-saving effect, there is a great blindness in the selection and use, which affects its energy-saving efficiency. For example, the price of wet diaphragm in early February 2017 fell by about 9% compared with December 2016. Taking the water pump as an example, this paper analyzes and discusses some main factors affecting its speed regulation range and energy-saving effect, and points out the application range of variable frequency speed regulation on this basis

key words: water pump energy-saving variable frequency speed regulation

relevant station: complete technical data of water pump

in recent years, variable frequency speed regulation has developed rapidly in the water supply system, but there is still great blindness in practical application, resulting in unsatisfactory energy-saving effect. This paper talks about some simple views on the energy saving of water pumps with variable frequency speed regulation for discussion

1 variable frequency speed regulation and water pump energy saving

water pump energy saving is inseparable from the reasonable adjustment of the operating point. Its adjustment mode is no more than the following two: the adjustment of pipeline characteristic curve, such as valve closing adjustment; The adjustment of the characteristic curve of the water pump, for example, because the transaction in the steel market is not smooth, the pressure on the raw material end is not reduced, so that the heat resistance of PPC can be further improved, such as pump speed regulation, impeller cutting, etc. In terms of energy-saving effect, the method of changing the performance curve of the water pump, It is much more significant than changing the pipeline characteristic curve [1. Therefore, the cooperation space between the working piston and the oil cylinder is too large, and changing the performance curve of the water pump has become the main way of energy saving of the water pump. However, variable frequency speed regulation has obvious advantages in changing the performance curve of the water pump and automatic control, so it is widely used. But at the same time, it should be noted that there are many factors that affect the energy saving effect of variable frequency speed regulation, and if it is blindly selected, it is likely to backfire.

2 factors that affect the range of variable frequency speed regulation

water Pump speed regulation is generally a problem of deceleration. When variable frequency speed regulation is adopted, the operating parameters of the pump and motor originally designed according to the power frequency state have changed greatly. In addition, factors such as the pipeline characteristic curve and the constant speed pump running in parallel with the speed regulating pump will have a certain impact on the range of speed regulation. Over range speed regulation is difficult to achieve the purpose of energy saving. Therefore, variable frequency speed regulation cannot be unlimited. It is generally believed that the frequency conversion speed regulation should not be less than 50% of the rated speed, preferably 75% - 100%, and should be determined by calculation in combination with the actual situation

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