Two of Finland’s major hydropower plants, located in the Arctic Circle, have been equipped with SF6-free circuit breakers by ABB.
Kemijoki Oy’s Matarakoski and Kelukoski plants, completed in 1995 and 2001, respectively, have an 11MW output and power approximately 10,000 homes.
The plants had been running on their original SF6-based HPA circuit breakers, but the aging circuit breakers were no longer in line with Kemijoki’s strict environmental diversification program or the latest global Dual Logo Standard. ABB’s Electrification Service team was able to provide a retrofit solution with a customized 12kV version of its MV VD4G vacuum circuit breaker family. This solution clears potentially harmful short-circuit faults in tens of milliseconds, preventing severe damage and lengthy plant downtime, said ABB, with resin-insulated vacuum interrupters guarantee higher protection of the core components, providing a complete asset protection solution that safely masters fault conditions with delayed current zeros and severe transient recovery voltages.
“Compared to a full overhaul of the complete medium voltage switchgear, we saved almost a month of downtime with the retrofit – taking just hours rather than several weeks – and in an industry where 24/7 power output is expected that’s a lot of vital energy production and lost revenue saved,” commented Jarkko Virtanen, Vice President, Electrical and Machinery Technology at Kemijoki Oy. “We also have a much more reliable operational procedure because it handles the currents much better, and cost-effectively extends the life cycle of our generator applications by at least another 20 years.”
Now that a successful blueprint is established, retrofit solutions are planned for other power plants, while the open switchgear system of Kemijoki’s larger and more heavy-duty power plants is being considered for the latest in DPA pressure breakers.
Image: Sixten Holm, Business Development Manager for ABB Electrification Service division in Finland (yellow jacket), with Jarkko Virtanen, Vice President, Electrical and Machinery Technology for Kemijoki Oy – at their Kelukoski plant in the Arctic Circle.
