Brief introduction of variable frequency constant pressure water supply system

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 variable frequency constant pressure water supply system implements stepless speed regulation on the pump motor. According to the water consumption and water pressure change, the microcomputer detects and calculates, automatically changes the pump speed to keep the water pressure constant to meet the water requirement. It is the most advanced and reasonable energy-saving water supply system. . Compared with traditional water towers, high water tanks, pressure tanks and other water supply methods, it has advantages in terms of investment, economics of operation, system stability, reliability, and automation.

The frequency conversion constant pressure water supply is generally generated by the pressure transmitter sampling water pressure signal and the system set pressure value to generate an output signal, and then the frequency converter controls the water pump motor speed to achieve constant pressure water supply. The faster the pump turns, the higher the water pressure that can be delivered to a distant or higher floor. In the constant pressure water supply pumping station, the inverter often adopts the analog quantity control mode. This requires the analog control module of the PLC. The analog input terminal of the module receives the analog signal sent by the sensor, and the output end sends the given value and feedback value. Compare and calculate the analog control signal obtained by PID, and change the output frequency of the inverter according to the change of the signal. PLC control not only reduces system control wiring, improves reliability, realizes the above hardware with software, and is easy to maintain. It fully utilizes the advantages of flexible configuration of programmable controller, reliable control, convenient programming and on-site debugging, making the whole system Stability has a reliable guarantee.

The variable frequency constant pressure water supply system takes the pipe network water pressure (or the user water flow rate) as the set parameter, and controls the output frequency of the frequency converter to automatically adjust the rotation speed of the water pump motor to realize the closed loop adjustment (PID) of the pipe network water pressure. The water supply system automatically stabilizes at the set pressure value: when the water consumption increases, the frequency increases, the water pump speed increases, and the water supply volume increases accordingly; when the water consumption decreases, the frequency decreases, the water pump speed decreases, and the water supply volume decreases accordingly. Small, this guarantees the water supply efficiency users' requirements for water pressure and water volume, and at the same time achieves the purpose of improving the quality of water supply and water supply efficiency, "how much water is used, how much water is supplied"; the equipment does not need to build high water tanks, water towers, The water quality has no secondary pollution and is an ideal modern building water supply equipment.

The variable frequency constant pressure water supply system uses a potentiometer to set the pressure (also can be set inside the panel), and uses a pressure sensor (feedback 4~20mA) to detect the pressure in the pipe network. The pressure sensor sends the signal to the inverter PID circuit. After the PID loop is processed, a water increase or decrease signal is sent to control the motor speed. If the pressure is still insufficient or too large within a certain delay time, the other frequency pump is started by the frequency converter/frequency conversion of the inverter, so that the actual pipe network pressure is consistent with the set pressure. In addition, with the reduction of water consumption, the inverter automatically reduces the output frequency and achieves the goal of energy saving.

The use of frequency conversion equipment to achieve constant pressure water supply, compared with the use of regulating valves to achieve constant pressure water supply, energy saving effect is very significant (can be calculated according to specific circumstances).

1. Starting balance, the starting current can be limited to the rated current, thus avoiding the impact on the grid during starting;

2, because the average speed of the pump is reduced, which can extend the service life of pumps and valves;

3. It can eliminate the water hammer effect during start and stop (water hammer effect: when starting and stopping directly, the liquid kinetic energy will increase sharply, resulting in great impact on the pipe network and great destructive power).

(1) When the system starts to supply water, the frequency conversion operation;

(2) According to the needs of constant pressure, the three pumps shall be connected and withdrawn according to the principle of “first open first stop”;

(3) In the case of small water consumption, if one pump continuously runs for more than 3 hours, it will switch to the next pump, that is, the system has “reverse pump function” to avoid long-term operation of one pump;

(4) There are delays when the three pumps are started to reduce the impact on other electrical equipment when the current is too large;

(5) It is necessary to have a perfect alarm function;

(6) There are two manual and automatic control functions for the operation of the motor.

1. Adopt programmable controller, the program is flexible and changeable, with high precision, high reliability, many functions and fast response.

2, are equipped with a steady-state pump or regulator tank regulator, when the water consumption is small to a certain value, the main pump can stop running, reduce the mechanical wear of the pump motor and save energy.

3. The pumps are soft-started to extend the life of the equipment and eliminate the impact of the starting current on the grid.

4. According to the change of water consumption, the water pump cycle frequency conversion operation, the first stop of the first start, so that the pump balance work, when one pump runs for six hours or twenty-four hours, automatically switch to another.

5, the biggest feature is double constant pressure control, a set of equipment that can be used for life fire protection, saving investment for users, and dual-use one machine, greatly improving the use efficiency.

6. Compact structure, small floor space, fast installation, low investment, stable operation and no pollution.

It adopts variable frequency constant pressure water supply, which has the advantages of high efficiency, energy saving, stable pressure, reliable operation, simple operation, less land occupation, low noise, no pollution, low investment and high efficiency. widely used in:

1. Centralized living water supply system for residential areas, residential buildings, and villages and towns.

2. Circulating pumps and cooling water supply systems for various types of central air conditioners.

3. Living water supply systems for high-rise buildings, hotels, restaurants, etc.

4. Integrated market, office building, commercial building living water supply system.

5. High-rise building hot water supply and hot water heating system and fire water supply system.

6. Production and domestic water supply of industrial and mining enterprises, and constant pressure flow water supply process.

7. All kinds of waterworks and modern agricultural irrigation.

8. Various constant pressure flow control systems for constant pressure oil supply, constant pressure gas supply, constant pressure air supply, etc.