After many years of continuous operation, the Variable Frequency Drive (VFD) system at the NS BlueScope Vietnam factory gradually revealed limitations in reliability and availability.
- The VFD equipment had been operating for a long period, with many components deteriorating, increasing the risk of unplanned downtime.
- Siemens had discontinued this product line and no longer provided support.
- Risk of spare equipment shortages, causing difficulties when replacement is required.
- Outdated technology leading to high energy losses.
- High spare parts cost as well as high operating cost.
- Maintenance and servicing of the system faced many difficulties.
- High cost of hiring foreign service providers, difficult to control.
The upgrade was not simply equipment replacement but had to be implemented within a very short shutdown window. For each section in the line, the entire upgrade scope had to be executed within 5–7 days. Within this timeframe, ESEC had to handle the technological functions on T400 while maximizing the use of the existing installation infrastructure and cabling system.
In addition, the PLC control architecture was not allowed to change significantly, and communication connections with related systems had to be maintained. Particularly, after the upgrade was completed, the line still had to ensure line speed and tension accuracy within the allowable limits, without affecting product quality and the production schedule.
Based on the technical requirements and operating conditions of the factory, ESEC implemented a retrofit solution from the Simovert system to the Siemens Sinamics S120 platform, integrating both hardware and software to ensure long-term operational efficiency.
For hardware:
- Redesign the new control cabinet system based on the existing cabinet platform.
- Upgrade the Simovert Master Drive VFD to the latest series – Siemens Sinamics S120.
- Supply all new components inside the control cabinets.
- Ensure the design complies with standards (Australian / New Zealand Standards): AS/NZS 3000 – Wiring Rules, ….
For software:
- Rebuild the communication telegram between Drive & PLC.
- Program the integration of the new drive system into the existing PLC S7-400.
- Configure motor parameters with the new S120 drive.
- ID Run & Turning drive system.
- Ensure stable system data communication after the upgrade with other software systems.
Facing strict technical requirements from NS BlueScope Vietnam, ESEC approached the project with a direction of synchronously handling both hardware and software to ensure stability, scalability, and long-term operation of the entire production line.
Hardware
- To optimize the lifecycle and ensure long-term support capability, the system was selected based on the latest product platform with a required design lifecycle of 10–20 years.
- To save energy for the production line, which includes many motor applications that tend to feed power back to the grid due to rapid braking or pulling effects, ESEC selected the Smart Line Module with the Regulated Infeed / Regenerative Feedback function applied to the input power supply of the drive. This prevents unwanted reactions to the power supply, allows braking energy to be fed back to the grid instead of being dissipated through braking resistors, and enhances stability against grid fluctuations.
- The upgraded system applies the Multi-Axis Drive System with Siemens multi-axis control technology, ensuring stable operation for applications using the Master / Slave control mechanism.
Software
- Apply multi-axis tension control functions to help the system maintain stable tension in areas requiring stable tension such as: Furnace, zinc pot, coater, and tension reel.
- Apply new modern control technologies of the Sinamics drive system such as: FlyRestart for windmilling applications, vector closed-loop motor control, and technology control for bridle machine control functions using “Speed with Torque Compensation” technology to ensure stable tension control of the bridle.
- Upgrade the control functions of T400 on Simovert to the DCC product line of Sinamics, enabling stable high-speed unwind and rewind control for the Entry and Exit sections without coil collapse or oval deformation.
The project was completed on schedule, fully meeting the technical and operational requirements initially set. After the upgrade, the Simovert Master Drive was converted to Sinamics S120, enabling the line to operate stably, smoothly, and effectively control tension across the entire line.
- Complete the upgrade of all Simovert drives to Sinamics S120 for the plant production line.
- The system operates stably and smoothly, with well-maintained tension stability.
- Equipment is well warranted and supported after the upgrade, improving operational safety for the plant.
- Energy saving for the plant thanks to the multi-drive control mechanism sharing a common DC-Bus and using Smart Line Module with regulated infeed / regenerative feedback mechanisms.
- The operation and maintenance interface of the equipment is modern, common, and friendly for plant engineers.
The success of the project upgrading the entire VFD system of the steel galvanizing line at NS BlueScope Vietnam further affirms ESEC’s practical implementation capability, while opening up many long-term cooperation opportunities with steel plants in system retrofit programs and operational efficiency optimization in the future.
BD & MKT
