Project Background

A customized rectifier transformer system was designed and commissioned for a large-scale electrolysis facility in Zambia. The system is tailored to provide stable and efficient DC power supply for 46 electrolytic cells, ensuring precise control over the electrochemical process.

Key Specifications​

• ​​Transformer Rating​​: 1650kVA, 11kV primary voltage.
• ​​DC Output​​: 0–110V adjustable voltage, 13kA DC current.
• ​​Application​​: Electrolysis system (46 cells).
• ​​Quantity​​: 1 complete set.

Rectification & Voltage Control System

​​Rectification Method​​:

​​12-pulse thyristor (SCR) rectification​​: Utilizes two parallel 6-pulse bridges with phase-shifted inputs (30° displacement) to minimize harmonic distortion and improve power quality.

​​Voltage Adjustment​​:

• Coarse Adjustment​​: On-load tap changer (OLTC) integrated into the transformer for stepwise voltage regulation (±10% range).
• ​​Fine Adjustment​​: Thyristor phase-controlled rectification enables continuous, smooth voltage tuning from 0% to 100% of the rated DC output voltage (Udn).
• ​​Combined Range​​: Seamless 0–100% output adjustability, ensuring optimal process control for varying electrolysis loads.

Key Features​

• High Efficiency​​: 12-pulse design reduces input current harmonics (<8% THiD), compliant with IEEE 519 standards.
• ​​Dual Control Flexibility​​: OLTC handles major voltage steps, while thyristors provide sub-1% precision for dynamic process requirements.
• ​​Robust Design​​: Transformer insulation class (H-level) and forced-air cooling (FOA) suit Zambia’s tropical climate (ambient temperature ≤45°C).
• ​​Protection​​: Integrated overcurrent, overtemperature, and short-circuit safeguards via PLC-based monitoring.

Operational Benefits​

1. ​​Energy Savings​​: 98.2% system efficiency at full load reduces operating costs.
2. ​​Process Stability​​: ±0.5% voltage ripple ensures consistent electrolytic deposition.
3. ​​Adaptability​​: Automatic load-following mode adjusts output in real-time based on cell conditions.

​​Conclusion​

This 12-pulse rectifier transformer system combines advanced thyristor technology with transformer-based voltage control, delivering a reliable and adaptable DC power solution for Zambia’s electrolysis industry. The design addresses critical operational needs—harmonic mitigation, precision control, and harsh-environment durability—while enabling scalable production capacity.