Introduction：
Water resources are an important factor for economic development and sustainable social development, and urban sewage treatment rate has become an important symbol of whether a region is civilized or not. The serious pollution and increasing scarcity of water resources has now become a topic of concern all over the world. With the development of economy in China, the amount of urban sewage and industrial wastewater has increased sharply, providing a huge market space for the water treatment industry. In sewage treatment plant, aeration blower and submersible pump are the core equipment of sewage treatment. D32 inverter has a wide range of applications in sewage treatment, and has achieved good economic and social benefits.
Features：
D32 is a wall-mounted inverter, the power range is 0.75KW-500KW, the voltage level of the incoming line voltage is 380V-480V, and the control method is vector control without speed sensor.
D32 has a wealth of substations, 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.
Advantage：
Large starting torque, 1.5 times the torque output at open-loop 0.5Hz, meeting the requirements of submersible pump operation;
It has the advantage of fast torque response, and when the load fluctuates, the current fluctuation is small;
It has good overload capacity and environmental adaptability, and has high operational reliability;
Super power grid adaptability, anti-power grid fluctuation ability up to ±15%, to ensure the stability of output voltage, current, speed
Excellent current limiting characteristics, strong overload capacity, can effectively reduce frequency conversion overload, overcurrent protection, and maximize production continuity;
It has strong environmental adaptability, and the completely independent air duct design can greatly improve the resistance to harsh environments such as oil pollution, dust and damp heat.
System Introduction：
In this system, the main motor of the 110KW submersible pump is driven by the D32 110KW inverter, which is centrally controlled by the DCS system in the central computer room, and can also be operated locally.
Technical Parameter：
| Inverter technical parameters | Device configuration | |
 Model: D32-X | Output current: 215A | One D32 inverter |
| Input voltage: 3-phase, 380-480V | Frequency range: 0-400Hz | 110KW submersible pump and motor |
| Input frequency: 50/60Hz ±5% | Overload capacity: 150%, 60 seconds | DCS Control System |
| Output power: 110KW | Ambient temperature: -10-40°C | |
| Output voltage: 0-480V (the maximum value is determined by the input voltage) | Protection level: IP20 | |
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 sewage treatment submersible pump control system using D32 frequency converter has been put into operation for more than three years, and has achieved good economic and social benefits:
The control device operates reliably, has good environmental adaptability, can resist harsh environments such as oil pollution, dust and damp heat, and has a low failure rate;
Excellent current limiting characteristics, strong overload capacity, can effectively reduce frequency conversion overload, overcurrent protection, and maximize production continuity;
According to the needs of the process, make the motor soft start/soft stop, so that the sudden twist and water hammer phenomenon can be solved;
The economic benefits are remarkable, the power saving effect is more than 20%, and the entire investment increased by the frequency conversion control system can be recovered in more than one year.
Customer Benefits：
Eliminates many tedious manual operations, unsafe hidden dangers, and improves work efficiency;
Greatly reduces the impact on the machinery when the pump is started, and reduces maintenance costs;
The comprehensive protection function of the inverter ensures maximum production continuity;
The economic benefits are significant, and the entire investment increased by the frequency conversion control system can be recovered in more than one year.