China Frequency Inverter for Water Supply

Compared with the traditional water tank and water tower water supply, the variable frequency constant pressure water supply has the advantages of stable water supply pressure, high power saving rate, good reliability, and no pollution to water resources. The following is an example of a water supply factory using a frequency converter to drive three pumps to achieve constant pressure water supply. The special frequency converter for water supply developed by Shenzhen Dolycon Technology Co., LTD. and its application in the constant pressure water supply system are introduced in detail.

Water supply system is an indispensable part of national production and life. The traditional water supply method covers a large area, and the water quality is easy to be polluted. The main disadvantage is that the water pressure cannot be kept constant, resulting in some equipment not working properly. Frequency conversion speed regulation technology is a mature AC motor stepless speed regulation technology. Under the situation that the demand for safe production and water supply quality is becoming more and more urgent, the solution of constant pressure water supply through frequency conversion speed regulation is more and more recognized by the public.

The field application is a water supply plant in Shenzhen. One 4KW inverter is required to control 3 pumps to achieve constant pressure water supply. The inverter is required to automatically adjust the speed according to the actual water pressure, and determine whether it is necessary to invest in the second and third pumps. A pump is involved in the water supply.


Control plan

The water supply system installs a pressure sensor on the water supply official website to convert the water pressure signal into a 4~20mA current type signal acceptable to the inverter. When the system is working, the pressure sensor detects the water pressure in real time, the frequency converter receives the pressure signal, and the differential adjustment between the actual pressure signal and the given pressure signal constitutes a closed-loop pressure system. The frequency converter changes the speed of the pump motor by changing the frequency through the PID output. However, the upper and lower limits of the operating speed of the variable frequency pump limit that a single pump cannot cope with the peak and low peak periods of water consumption. The special frequency converter CT110 for constant pressure water supply developed by Shenzhen Dolycon Technology Co., LTD. combines the above conditions and expands the special logic for water supply. Through the two auxiliary relays and the number of enabled units, the peak and valley water consumption can be automatically adjusted to ensure the constant pressure of the water supply network. to meet the water demand of users.

CT110 water supply logic description

CT110 series special frequency inverter has built-in water supply logic, and optimized PID control ensures constant water pressure. At the same time, it automatically processes the action logic of adding and subtracting pumps, and automatically adjusts the frequency during the action stage of adding and subtracting pumps to ensure that the water pressure is still stable and controllable when adding and subtracting pumps.

The water supply logic is explained as follows
1. Pumping logic: When the water pressure is continuously lower than the set pressure, the inverter will run at an increased speed. When the inverter accelerates to the pumping frequency point (F13.01), if the water pressure is still lower than (the set pressure percentage) (adding pump pressure tolerance percentage F13.02), it is considered that the current number of pumps is not enough, and it is necessary to increase the pump operation. After the pumping delay time is reached, the auxiliary relay will act, and the pumping will run at this time.
2. Auxiliary logic for pumping: the newly added pump is a power frequency pump, and the water pressure may rise rapidly during the pumping process. Therefore, the frequency conversion pump will automatically reduce the frequency during the pumping process to avoid excessive water pressure during pumping. , the deceleration time of the inverter at this time is determined by F08.01.
3. Pump reduction logic: When the water pressure continues to be higher than the set pressure, the inverter will reduce operation. When the inverter decelerates to the pump reduction frequency point (F13.04), if the water pressure is still lower than the set water pressure percentage ) + (reduced pump pressure tolerance percentage F13.05), it is considered that the current number of pumps is too many, and the operation of the pumps needs to be reduced.
4. Auxiliary logic for pump reduction: The newly reduced pump is a power frequency pump. During the pump reduction process, the water pressure may drop rapidly. Therefore, during the pump reduction process, the frequency conversion pump will automatically increase the frequency to prevent the water pressure from being too low when the pump is added. , the acceleration time of the inverter at this time is determined by F08.00.
5. Sleep function logic: When the auxiliary pump has been stopped and the water pressure is still high, the inverter will run at a reduced speed. When the operating frequency of the inverter is lower than the frequency point of the reduced pump, the inverter will automatically sleep, and the keyboard will display the "SLEEP" state.
6. Sleep wake-up logic: In the sleep state of the inverter, when the water pressure is low, the set frequency calculated by PID is higher than the wake-up frequency setting, and the current pressure is lower than (set water pressure percentage) - (wake-up pressure tolerance) Percentage F13.02), it is considered that the variable frequency pump needs to run, and after the wake-up delay, the variable frequency pump wakes up from sleep.
7. Priority of water pump control: The priority of water pump participation in operation is: variable frequency pump > auxiliary pump 1 > auxiliary pump 2. That is, when the pump needs to be added, the variable frequency pump is added first, then the auxiliary pump 1, and finally the auxiliary pump 2; when the pump needs to be reduced, the auxiliary pump 2 is first reduced, then the auxiliary pump 1 is reduced, and finally the inverter is reduced for sleep standby.

Introduction of Dolycon CT110 special variable frequency drive for water supply
Based on the DSP control system, the CT110 inverter adopts the domestic leading non-PG vector control technology, and cooperates with a variety of protection methods, which can be applied to asynchronous motors and provide excellent driving performance. The product has greatly improved the ease of use and environmental adaptability of customers in terms of air duct design, hardware configuration, and software functions.

Technical Features
◆ Special logic for water supply: The water supply logic based on on-site working conditions, the constant pressure control performance is more stable.
◆ Accurate motor parameter self-learning: accurate rotating or static motor parameter self-learning, convenient debugging, simple operation, and provide higher control accuracy and response speed.
◆ Vectorized V/F control: automatic stator voltage drop compensation, VF control can also ensure excellent low frequency torque characteristics.
◆ Software current limiting and voltage limiting function: good voltage and current control, effectively reducing the frequency of inverter protection.
◆ Multiple braking modes: Provide multiple braking modes for quick stop.
◆ High reliability design: The higher over-temperature point and good protection level of the whole machine are more suitable for the use environment of the water supply industry.
◆ Speed tracking restart function: realize the smooth start of the rotating motor without impact.
◆ Automatic voltage adjustment function: When the grid voltage changes, it can automatically keep the output voltage constant.
◆ Comprehensive fault protection: overcurrent, overvoltage, undervoltage, overtemperature, phase loss, overload and other protection functions.

The frequency conversion control technology is applied to the field of constant pressure liquid supply, and a special control module is added to the control to provide an optimized constant pressure water supply scheme. Using this special frequency converter to assemble the water supply automatic control system has the advantages of low investment and high degree of automation. It has complete protection functions, reliable operation, simple operation, remarkable water saving and electricity saving effect, especially it does not cause secondary pollution to water quality, and has excellent performance-price ratio.

For more information about CT110 special frequency converter for water supply, please contact us.