Introduction：
With the development of power technology and the improvement of frequency conversion speed regulation technology, the intelligent water supply control method with frequency conversion speed regulation as the core has replaced the previous water supply method of multi-pump switching and valve adjustment. During variable frequency speed regulation, the starting current can be limited within the rated current, thus avoiding the impact on the power grid during starting. Due to the smooth start of the pump, the average speed of normal operation is reduced, thereby extending the life of equipment such as pumps and valves. At the same time, it can eliminate the water hammer effect when starting and stopping. With its stable performance, simple operation mode and perfect function, the frequency converter will enable the water supply system to save electricity, water and manpower, and finally achieve the purpose of high-efficiency operation.
Features：
D32 is a cabinet-mounted inverter, the power range is 0.75KW~500KW, the incoming voltage is 380V~480V, and the control methods are sensorless vector control and vector control. The speed sensorless vector control is a kind of vector control, but there is no speed sensor, and the speed feedback value of the motor is estimated through the calculation of the motor model. The control accuracy and dynamic performance of the speed sensorless vector control are not as good as the vector control with speed closed loop, but it also has the advantages of simple system, no need to maintain speed sensors, and low price, especially for fans and pumps. The traditional V/f control also does not need a speed sensor, but for high-power fan and pump motors, such as V/f control without current loop control, it is easy to cause current fluctuations. The speed sensorless vector control not only has a speed closed loop but also a current closed loop, and the steady-state current of the motor is more stable.
D32 has a wealth of client terminals, including 8 digital inputs (LI1~LI8), 2 analog inputs (AI), 2 relay outputs (TA), 2 analog outputs (AO), 5V auxiliary power supply for analog power supply Fixed input, 24V auxiliary power supply is used for digital input, all LI/TA, AI/AO can be freely programmed to define functions. MODBUS interface is standard configuration of D32, no option is required. The D32 can be connected to higher-level automation systems via MODBUS.
D32 series inverter has built-in PID function, which is more flexible in operation. There are many ways to control the interface, which can be hard-wired or communication.
Advantage：
System Introduction：
In this system, three deep well pumps are used, and one 45KW deep well pump is used as a normally open pump to maintain the basic water supply function. A 75kW deep well pump is used as the main control pump, and a frequency converter constant pressure automatic water supply control device is installed. When the water consumption changes, the speed of the pump is adjusted to realize constant pressure water supply of the water supply network. A 75kW deep well pump is installed with a set of full digital The AC motor soft start controller is used as an auxiliary control pump. When the water supply volume changes greatly, if the main control pump has been working at full frequency (or minimum frequency), the pressure of the water supply pipe network cannot be guaranteed to be constant. The controller makes the auxiliary control pump start (or stop) running, and then the main control pump runs at a variable speed to adjust the water pressure of the pipe network to keep it constant.
1- Power switch 2- One-way water valve 3- Pump reactance 4- Deep well water source 5- Pressure sensor
Technical Parameter：
| Inverter technical parameters | Device configuration | |
 Model: D32-X | Output current: 150A | One D32 inverter |
| Input voltage: 3-phase, 380-480V | Frequency range: 0-400Hz | 75kW 1 constant pressure control main control pump and motor |
| Input frequency: 50/60Hz ±5% | Overload capacity: 150%, 60 seconds | 75kW 1 constant pressure control auxiliary control pump and motor |
| Output power: 75KW | Ambient temperature: -10-40°C | 45kW 1 normally open pump and motor |
| Output voltage: 0-480V (the maximum value is determined by the input voltage) | Protection level: IP20 | 45kW 1 spare pump |
| One microcomputer | ||
| pressure sensor | ||
On site usage：
According to the on-site space situation, a D32 series inverter is installed in the control cabinet, and the inverter installation and on-site motor are as shown in the figure
Running Result：
The constant pressure water supply system using D32 inverter has been put into operation for more than three years, and has achieved good economic and social benefits:
The control device operates reliably and has a low failure rate;
The water supply pressure is stable, which eliminates the disadvantages of high-rise households cutting off water during peak water use and excessive pipe pressure during water trough periods;
Solve the problem of sand removal when the pump is turned on and the overflow problem during operation;
The economic benefits are remarkable, and the actual operation statistics show that 432,600 kWh of electricity can be saved in one year. Calculated at 0.3 yuan per kilowatt-hour, about 129,800 yuan in electricity costs can be saved. More than one year can recover all the increased investment of the constant pressure water supply automatic control system.
Customer Benefits：
The water pressure of the water supply pipe network is stable and does not change with the change of water consumption, which improves the quality of water supply;
It avoids the phenomenon of running water and water leakage caused by the abnormal increase of water pressure in the water supply pipe network, and reduces the maintenance cost;
The energy-saving effect is remarkable, and the increased investment in the constant pressure water supply system can be fully recovered in more than one year;
The waste of water resources is avoided, and the further expansion of the funnel area of water level drop formed by excessive exploitation of groundwater is prevented.