Project background
The 250MW photovoltaic power station in Warren, Missouri is the key node of the central and western power grid, with an average annual power generation of 380 million kWh. The project adopts double split winding box transformer (model: ZGSL-G-3600/34.5), which is connected to the power market through 220kV grid-connected lines.
Fault analysis
In May 2025, the operation and maintenance team found that the insulation resistance of the low voltage side of #4 main transformer plummeted to 0.5 mω (standard value ≥ 100 mω). The failure resulted in a direct economic loss of $23,000 per day, and triggered the NERC reliability standard alarm.
Emergency response
Our technical team completed within 10 hours: 1. Equipment replacement: hoisting 3600kVA box transformer (including intelligent temperature control system) 2. All tests: Unbalance of DC resistance ≤1.2%(IEEE 57.12.90 standard) The ratio change error is controlled within 0.25% The insulation resistance is restored to 150MΩ(2500V megohmmeter). 3. Grid-connected debugging: realize seamless switching from cold standby to full load operation.
Cooperation results
After the new transformer is put into operation, the temperature rise is reduced by 12K. Eaglerise Company has signed a strategic cooperation agreement with us, covering the preventive maintenance and renovation of the following five power stations.