Abstract : Variable frequency drive (VFD) technology is a key energy-saving technology project promoted under the National Ninth Five-Year Plan. The significant energy-saving effects of introducing VFD technology into water supply equipment are widely recognized. However, there is confusion regarding its application. This article presents the author's views for discussion among colleagues; further clarifies the characteristics of VFDs; and identifies some existing problems and solutions in current applications, hoping to contribute to the field.
Keywords : frequency converter; water supply system; water supply equipment
0 Introduction
The "Outline of Energy Conservation Technology in China" proposes that water pumps and fans should maximize their energy-saving effects, and it is also a key energy-saving technology project promoted by the National Ninth Five-Year Plan. With the implementation of the "Guidelines for Planning and Design of Urban Demonstration Communities in the 2000 Well-off Urban Housing Science and Technology Industry Project," specific regulations have been made regarding the selection of building materials and equipment for residential communities, requiring priority to be given to energy-saving, technically reliable, and space-saving products and equipment in design and construction. Therefore, frequency converters have already seen initial applications in water supply systems, but due to some misunderstandings, their application scope and usage methods have been negatively impacted. Accurate understanding and correct action are worth more than a dozen guidelines.
1. How to understand the frequency converter in a water supply system
In recent years, due to insufficient water pressure in municipal water supply systems, especially during the dry season, some cities experience water shortages even on the third floor during peak water usage times. Therefore, water supply equipment needs to be installed in residential areas to increase water pressure. The main types of water supply equipment include: elevated or low-level water storage tanks, pressure tanks, and variable frequency drive (VFD) water pumps. When discussing these, VFD technology is described as an energy-saving technology, but VFD water pumps are relatively energy-intensive.
Elevated water tanks are located on the rooftops of residential buildings. Water from the municipal water supply network is pumped into them, and the water flows by gravity to users. The advantage is simple control, using a mercury float relay to regulate the water level. It can supply water to several lower floors. The fatal flaw is that because it's on the roof, it's usually secured with a heavy-duty lock. Over the course of a year, the bottom of the tank accumulates over a foot of silt, containing dead rats and insects, which residents often consume year-round. In response to this situation, my country banned the use of elevated water tanks in 2000.
For details, please click: Application of Frequency Converters in Water Supply Systems
