Application of VFD in Constant Pressure Water Supply System

The constant pressure water supply speed regulation system can ensure constant water pressure throughout the day through the frequency conversion control system according to the change of water consumption, so as to meet the needs of people at different times. It is an advanced and reasonable energy-saving water supply system.

1. Analysis of constant pressure water supply system and frequency conversion technology

The frequency conversion constant pressure water supply system refers to the water supply method in which the outlet pressure remains constant when the water consumption in the water supply network changes. The outlet pressure value of the water supply pipe network is determined according to the needs of users, and the pressure value can be adjusted according to the needs. The traditional constant pressure water supply method is realized by using water towers, high water level tanks, air pressure tanks and other facilities.

In recent years, with the increasing maturity of frequency conversion speed regulation technology, its remarkable energy-saving effect and reliable and stable control mode have been widely used in water supply systems. The frequency conversion constant pressure water supply system implements stepless speed regulation for the water pump motor. According to the water consumption and water pressure changes, it can automatically change the water pump speed through microcomputer detection and calculation to keep the water pressure constant to meet the water requirements. It is the most advanced and reasonable energy-saving water supply system. . Compared with traditional water supply methods such as water towers, high-level water tanks, and pressure tanks, it has advantages in terms of investment, operating economy, system stability, reliability, and automation. The water pump in the traditional water supply system can only run at the rated frequency, which not only cannot guarantee the water demand of people during the peak period, but also causes energy waste. With the development of electric power technology, the frequency conversion speed regulation technology is becoming more and more perfect. The intelligent water supply control system with frequency conversion speed regulation as the core has replaced the previous water supply equipment such as high-level water tanks and pressure tanks. It starts smoothly and the starting current can be limited within the rated current. Thereby avoiding the impact on the power grid when starting; because the average speed of the pump is reduced, the service life of things such as pumps and valves can be extended; the water hammer effect when starting and stopping can be eliminated. Its stable and safe operation performance, simple and convenient operation mode, and complete and thoughtful functions will enable water supply to realize water saving, electricity saving, manpower saving, and finally achieve the purpose of high-efficiency operation.

2. Characteristics of constant pressure water supply by frequency converter

(1) High efficiency and energy saving. Compared with traditional water supply methods, frequency conversion and constant pressure water supply can save energy by 30%-60%.

(2) Small footprint, low investment and high efficiency.

(3) Flexible configuration, high degree of automation, complete functions, flexible and reliable, and can be unattended.

(4) Reliable operation. The system realizes soft start, eliminates the impact of large starting current, reduces the mechanical damage to the motor caused by the mechanical starting torque, and prolongs the service life of the motor and pump.

(5) The system can set the pressure according to the demand, and the system automatically adjusts the speed of the water pump and the number of pumps running according to the set pressure, so that the equipment can run in the best state of high efficiency and energy saving, thus achieving the energy saving purpose of saving water, electricity and manpower .

(6) Because it can realize soft stop and soft start of the water pump, and can eliminate the water hammer effect (water hammer effect: when starting and stopping directly, the kinetic energy of the liquid increases sharply, resulting in a great impact on the pipe network, which has a great impact destructive power).