The term "constant pressure water supply" refers to a method of supplying water where the outlet pressure remains consistent despite changes in water consumption. By integrating variable-frequency drives, PID regulators, microcontrollers, and PLCs, a control system can be established to regulate pump output flow and achieve a constant pressure water supply. The application of variable-frequency drives in constant pressure water supply has gained popularity within the water supply industry.

  The key characteristics of the variable-frequency constant pressure water supply system are as follows:

  1. Energy efficiency: The most notable advantage of a variable-frequency constant pressure water supply system, with potential savings ranging from 10-40%. It should be noted that energy savings decrease as flow rates increase.\

  2. Reliable operation: The variable-frequency constant pressure water supply system ensures a stable water supply pressure within the system, and the pump is smoothly started by the variable-frequency drive. This allows for seamless transition of the pump from its rated frequency to a variable frequency, eliminating any impact and preventing network shocks. Additionally, it effectively avoids excessive network pressure that could potentially lead to pipe bursts.

  3. Sanitation and Water Conservation: The network pressure is adjusted based on actual water consumption, and the outlet volume of the water pump is automatically regulated to minimize water leakage. Upon implementing a closed-loop water supply system, all users receive direct pipe-supplied water, eliminating the need for water towers, rooftop tanks, and air pressure tanks. This approach also prevents "secondary pollution" caused by traditional methods of water usage and eliminates the necessity for regular tank cleaning.

 4. The control is highly flexible: Allowing for staged, scheduled, or manual water supply.

 5. The self-protection function is comprehensive: the new residential variable-frequency constant-pressure water supply system includes protection against over-current, over-voltage, under-voltage, phase loss, short circuiting, instant power failure, overload and stall conditions. It also features low liquid level protection and a main pump rotation control function. This complete functionality enables fully automatic operation without the need for personnel in the pump room. Periodic inspections and maintenance are only required. In case of any pump failure, an alarm message will be automatically sent to the upper-level computer while activating a standby pump to maintain water supply balance. If there is a malfunction in the automatic control system, users can switch to manual operation mode to ensure continuous water supply.

6. By utilizing variable-frequency drives (VFDs), equipment life is extended and power grid stability is protected: VFDs prevent motors and pumps from running at their rated speed for prolonged periods of time which reduces mechanical wear and lowers pump failure rates. The main pump rotation control function ensures even wear distribution among all pumps while preventing rust formation. This extends the service life of pumps significantly. Additionally, VFDs enable soft start operations by providing continuous speed adjustment during motor start-ups and shutdowns which eliminates large current impacts on motor coils as well as on the power grid itself thereby eliminating water hammer effects caused by sudden changes in flow rate.