NATIONAL Grid had three similar close calls in as many months before last week’s blackout left thousands stranded.
It blamed Friday’s rare nationwide power cut on a slip in the grid’s frequency after two power generators shut down.
National Grid chief executive John Pettigrew denied being on holiday during Friday’s power outage[/caption]
The operator is already under investigation by the energy watchdog after the first blackout in more than a decade.
But industry sources have told The Guardian that the National Grid had been aware of the blackout problem for years and had warning signs.
Since May there has been a severe dip in the grid’s frequency from its normal range of about 50Hz, it is claimed.
Sources have claimed that the frequency has fallen below 49.6Hz on three occasions in the past few months.
GRID BLACKOUT SCARES
All three units of EDF Energy’s West Burton power plant in Notts tripped offline and fell to the legal limit of 49.5Hz in June.
Last month, it fell to 49.58Hz and in May it fell to 49.55Hz.
They are thought to be the deepest UK falls since 2015. Friday’s blackout was triggered by a further slump to 48.88Hz.
National Grid said the events were not connected and there was “no trend or prediction of more frequency excursions”.
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It described them as “part of the normal day-to-day operation of the electricity system”.
Chief executive John Pettigrew denied he had been on holiday and said he had been at his desk all weekend. He said: “There is never a good time for a power cut.
“But ten to five on a Friday afternoon in August, when people are trying to get home to their families and friends after a hard week at work, is one of the worst.”
Train workers rescued passengers from a stranded train after six hours near Hatfield, Herts on Friday[/caption]
Passengers were given water after finally reaching Hatfield on a second train[/caption]
Emergency lights guided commuters who were plunged into darkness during rush hour at Clapham Junction[/caption]
Commuters were forced to walk in nearly complete darkness[/caption]
Passengers were forced to walk on the tracks after their train was evacuated[/caption]
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