A failed furnace transformer at Corus’s integrated iron and steel plant in Scunthorpe threatened the company with serious lost production – until ABB’s transformer service team came to the rescue.
Earlier this year, ABB’s on-site transformer diagnostic and repair service enabled one of Corus’s Scunthorpe plants to restore full production less than 10 days after the failure of a 132/33kV furnace transformer in the Basic Oxygen Steelmaking (BOS) facility.
Corus Scunthorpe is the UK’s largest integrated steel plant, able to produce 4.5 million tonnes per annum. The steelworks has three furnace transformers in the BOS plant, and an unexpected failure reduced the plant’s ability to manufacture some of the technically challenging grades of steel.
Taking the transformer off-site for a factory repair would have taken at least six weeks, while the current lead-time for a brand new transformer is 18–24 months.
Corus needed a speedy solution and turned to ABB’s UK power systems service team for help.
Diagnostic tests
A series of tests using non-invasive diagnostic techniques showed that the fault was in the transformer tap-changer in the main tank. This is quite a common problem with furnace transformers, as they operate under severe conditions compared with transformers in power network applications. They experience frequent cyclic loading, due to the operation of the high-voltage circuit breaker, as well as over-currents and over-voltages generated by short circuits in the furnace.
The good news for Corus was that ABB’s newly developed on-site repair service enabled the transformer’s active parts to be removed from the tank so that access could be gained to the faulty tap-changer. All the failed components were replaced on site, in a fraction of the time required for a factory repair. The whole unit was back in use ten days after the initial failure.