I. Project Overview

The Junshan’ao Water Replenishment Project is an important component of the zonal water replenishment system in the northern part of Dongting Lake. The project employs pump‑boat water intake, equipped with four vertical axial‑flow pumps and three double‑suction pumps, with a maximum daily pumping capacity of nearly… 50 Ten thousand tons. Upon completion, the irrigation diversion flow will be increased to 5.11 m³/s , the urban water supply capacity has reached 6 Ten thousand tons / The project has effectively addressed the needs for agricultural irrigation, domestic water supply, and ecological water replenishment within the embankment area.

In this project’s pumping station, multiple high‑power pump motors are required to start and stop frequently, and given their large ratings coupled with limited grid capacity, the performance of the motor‑starting equipment must meet extremely stringent requirements.

II. Challenges Faced by Pump Station Motors During Startup

1. High‑current surges: When a large induction motor is started directly, the starting current can reach several times its rated value, imposing a severe transient load on the power grid. This may cause a sudden voltage dip, thereby affecting the normal operation of other equipment connected to the same grid.
2. Mechanical Stress Damage: The impact torque generated during direct starting can subject the pump coupling, bearings, and piping system to excessive mechanical stress, thereby reducing equipment service life.
3. Frequent start–stop requirements: Depending on the inflow rate and water demand, the pumping station must frequently adjust the number of operating units; the reliability of the starting equipment directly affects the continuity of water supply.
4. Grid capacity constraints: The pumping station is located in a remote area, and the upstream grid has limited capacity; therefore, measures to limit starting current must be implemented to ensure grid stability.

III. Technical Solution for the Otto High-Voltage Soft Starter

In response to the aforementioned issues, the project selected a high‑voltage solid‑state soft starter manufactured by Otto Technology. This device employs thyristor series‑connection technology and achieves smooth motor starting by regulating the terminal voltage. Its key technical features are as follows:

1. Multiple starting modes: Supports current‑limiting start, voltage‑ramp start, torque‑control start, and other modes, allowing flexible selection based on the pump’s load characteristics. In this project, a current‑limiting method is employed. + The ramp‑composite control method effectively limits the starting current to a low level while ensuring sufficient accelerating torque.
2. Closed-loop control algorithm: The device is equipped with a high-performance microprocessor that continuously monitors motor current, voltage, and speed, dynamically adjusting the thyristor firing angle to ensure a smooth start-up process and prevent torque oscillations.
3. Comprehensive protection features: Integrated protections against overcurrent, overload, phase loss, three-phase imbalance, and thyristor overheating, with automatic bypass upon fault occurrence, ensuring the safe operation of the pumping station.
4. Communication interface: Supported Modbus 、 Profibus Standard protocols are available for connecting to pump stations. DCS System.

IV. Practical Application Results

In the actual operation of the Junshan’ao water‑replenishment project, the application of Otto high‑voltage soft starters has yielded results in the following areas:

1. Grid disturbances are significantly reduced: With precise current-limiting control, voltage fluctuations during startup are kept within acceptable limits, preventing interference with other loads on the same busbar and ensuring the stability of the pumping station and the surrounding power supply system.
2. The mechanical system is effectively protected: smooth torque output eliminates the mechanical shocks associated with direct starting, extending the service life of critical components such as the motor–pump coupling and bearings, and significantly reducing equipment maintenance intervals.
3. Enhanced Operational Flexibility and Reliability: In response to fluctuations in water levels and variations in water demand, the pumping station can flexibly start or stop units according to actual requirements. The startup process remains consistently smooth and well‑controlled, with no shutdown incidents caused by failed startups.

Overall, the application of this soft-start device not only resolves the starting challenges associated with high-power pump motors but also provides reliable support for the long-term safe, economical, and flexible operation of pumping stations.

V. Conclusion

The successful commissioning of the pump station for the Junshan’ao Water‑Supply Project has validated the technical feasibility of Changsha Auto Automation Technology Co., Ltd.’s high‑voltage soft‑starter in high‑power pump applications. With its precise current control, robust protection features, and excellent system compatibility, the device offers a mature, replicable solution to motor‑starting challenges in similar hydraulic pumping stations. For engineering professionals concerned with pump‑operation safety, grid stability, and energy conservation, high‑voltage soft‑start technology has unequivocally demonstrated its irreplaceable value.