Recently, the “integrated induction‑boost” retrofit project for Unit No. 5 at a certain power plant was successfully completed. As a core component of the motor‑drive system, the Changsha  ATA QB‑H06/10000 medium‑ and high‑voltage soft starter smoothly passed its full‑load commissioning, delivering outstanding heavy‑load starting performance and reliably driving an 8,400 kW high‑power axial‑flow fan, thereby providing a powerful boost to the power‑generation enterprise’s quality improvement and efficiency gains.

I. Project Background: “Integration of Water Diversion and Storage,” with technological upgrading now imperative.

The original induced-draft fan and booster fan of Unit 5 at this power plant were configured separately, leading to persistent issues such as low operational efficiency, a high plant‑use factor, and high maintenance costs. In response to the “dual carbon” goals and the industry’s call for improved quality and efficiency, the plant launched a retrofit project to integrate the induced‑draft and booster functions into a single unit, replacing the two separate fans with a new, high‑efficiency axial‑flow fan.

The substantial increase in motor power poses significant challenges to the reliability, heavy-load starting capability, and level of intelligence of high-voltage motor starting control systems.

II. Core Equipment of the Project: Medium- and High-Voltage Soft Starter

Following rigorous technical evaluation and comparison, the project ultimately selected medium- and high-voltage soft-start devices independently developed and manufactured by Changsha ATA. Two redundant, independent units were installed, each driving a newly commissioned axial-flow fan motor.

Product Model: ATA QB-H06/10000

Rated voltage:  6kV

Compatible motor power: 8400 kW (high-efficiency three-phase induction motor)

Load type: Axial fan (high rotational inertia, variable torque load)

Configuration Quantity: 2 sets (meeting the unit’s high-reliability requirements)

This equipment is responsible for the smooth, full‑range start-up of the axial fan—from standstill to rated frequency—and serves as the core component of the electrical drive system in the “integrated induction‑boost” project.

III. Product Highlights: Comprehensive Demonstration of Heavy-Load Starting Capability

Under the actual operating conditions of an 8,400 kW/6 kV ultra‑large‑capacity axial flow fan, the ATA QB‑H06/10000 medium‑ and high‑voltage soft starter demonstrates outstanding technical advantages and excellent engineering adaptability:

1. Ultra-large-capacity thyristor valve assembly design + magnetic triggering technology

It employs a series‑parallel thyristor topology with high voltage ratings and high current capacity, coupled with ATA’s patented magnetic triggering technology, to ensure robust suppression of current surges under full‑load starting conditions.

2. Intelligent control strategy, perfectly matched to the load characteristics of axial-flow fans.

It features a built-in composite start-up algorithm that combines voltage ramping with current limiting, and incorporates parameter‑adaptive optimization tailored to the high rotational inertia and variable torque characteristics of axial fans. The motor’s starting torque rises smoothly, effectively suppressing mechanical resonance and overcurrent surges.

3. High electromagnetic compatibility + Field-environment adaptability

The cabinet features a structure resistant to strong electromagnetic interference and a dual‑shielding design, enabling it to operate reliably in the complex electromagnetic environment of power plants as well as under installation conditions characterized by high dust levels and elevated temperatures. The control circuitry is rigorously isolated from the power circuitry, ensuring precise operation and zero false trips even in the presence of high‑frequency harmonics generated by axial flow fans.

IV. Project Commissioning: Successful on the First Attempt, Performance Verification

On May 13, 2026, the “integrated startup and load‑increase” retrofit project for Unit #5 of the power plant entered its critical phase of full‑scale load‑testing and commissioning. Two ATA QB‑H06/10000 medium‑high voltage soft‑starter units were used to drive the axial‑flow fan motors, conducting comprehensive tests covering full‑voltage starting, steady‑state operation, and bypass switching. The commissioning results were highly satisfactory:

• Smooth start-up The motor’s starting current is smooth and free of surges, and no protective alarms were triggered.
• Outstanding mechanical performance : During the start-up of the axial fan, no abnormal vibrations or unusual noises were observed, and both bearing temperature and vibration amplitude remained within excellent limits, highlighting the effective protection provided by the soft starter to the drivetrain.
• Non-intrusive bypass switching When the motor approaches its rated speed, the control system automatically issues a bypass command: first, it closes the bypass vacuum circuit breaker, then deactivates the thyristors. During this switching process, the current surge is virtually zero, enabling a smooth transition to line-frequency operation without inrush currents.

During commissioning, all technical performance indicators exceeded the design specifications, and both start-up control cabinets operated with remarkable stability, earning high praise from the power plant’s Technical Department, the maintenance contractor, and the supervising agency.

The successful commissioning of the power plant’s Unit #5 “integrated induction‑boost” retrofit project, coupled with the outstanding performance of its high‑voltage soft starter, underscores that Changsha ATA’s ATA QB‑H series high‑voltage soft starters have reached a high degree of maturity in large‑power, heavy‑load applications within the power industry.

With its outstanding heavy-load start-up performance, intelligent protection features, and high reliability, Changsha ATA Automation Technology Co., Ltd. effectively supports power generation enterprises in achieving the dual objectives of improving quality and efficiency while ensuring safe operations. Looking ahead, we will continue to deepen our expertise in motor drive and control, delivering higher‑quality motor drive and control solutions to industrial customers.