Power failure in the Southern Gotthard.

[M. Hardy-Randall]

At lunchtime today the overhead catenary in the southern area of the Gotthard lost power.

Approx four times per year the 132 kV line that serves this area is taken out of service for maintenance usually without problems. To power the overhead lines the hydro-electric generating station at Ritom supplies the power required, and is assisted by the frequency converter station [from 50 Hz to 16.6Hz] at Guibiasco to cover the extreme southern area. During the maintenance period which normally lasts one hour the Southern Gotthard is run in isolation to the rest of the Swiss Railway power grid.
However, this year something quite unexplained happened. The frequency of the power supply began to fluctuate outside of normal limits and the automatic safety devices at Ritom Power station shut down. As a result for one hour from 12.30 today [11/08/09] the whole of the train service south of the Gotthard Pass came to a halt. Buses were quickly brought into service to provide a limited service, to supplement the Postal bus service that runs alongside of the train service. At 13.30 power, at 15 kV 16.6 Hz AC, was restored to the overhead wires and normal service was resumed.

Not so long ago a similar thing happened when the supply from Italy failed and the power grid of the Swiss Railways was affected by a Domino effect as power supplies all over the country sequentially failed. On that night passengers trying to get home from work did not wonder when the train would arrive but if it would.