A £2m wind turbine was collapsed by the wind after violent storms and 50mph gales caused the 300-foot rotor’s blades to rotate at double their regular pace.
The turbine, which was almost the size of St. Paul’s Cathedral, was blasted apart by the ferocious winds and fell in February.
Families in the neighbouring South Wales village of Gilfach Goch described the sounds as like thunder and lightning.
An study conducted by manufacturer Nordex determined that a power failure led the blades to operate in a “overspeed condition” for more than four hours and revolve uncontrollably in gusts of 50 mph.
The energy generators are designed to shut down automatically when 55 mph winds are detected.
A spokesman for Nordex said: ‘A Root Cause Analysis investigation determined that a technical issue, starting within an Uninterrupted Power Supply cabinet for one of the blades, triggered an unprecedented chain of events in quick succession.
‘This disabled the main power supply and the backup power supply to each blade of the pitch system, therefore all three blades of the wind turbine were left without power resulting in a fixed state.
‘The wind speed conditions on the day increased putting the wind turbine into an overspeed condition until it collapsed.’
At around 6.50 a.m. on a Monday in February, villagers reported hearing a loud bang that reverberated across the valley.
The 2013-built, 10-turbine Pant y Wal wind farm supplied enough electricity for 18,000 houses until one of the turbines was damaged.
Ricky Williams, a local resident, characterised it as a clap of thunder in the early hours.
Other residents expressed concern about the safety of the turbines after the fall.
The Pant-Y-Wal wind farm’s turbines were assessed by Nordex, who concluded that the danger of human damage was minimal and no further action was taken.
A spokesperson for Nordex added: ‘Temporary measures are being implemented to reduce the likelihood further. A permanent solution is being developed to mitigate the residual likelihood.’