Lightning strikes are an on-the-job hazard

Acrophobia — an intense fear of heights — is an immediate disqualification for any highly skilled electrical engineer or technician with career aspirations for wind turbine maintenance and repairs.

Working on a narrow and exposed platform 80m above the ground, equivalent to a 33-floor building, is strictly reserved for those wanting an occupation with a bird’s-eye view.

Maintaining, testing and servicing 163 wind turbines with an installed capacity of 244.5MW near De Aar in the Northern Cape to ensure the more than R5bn investment by China’s green energy South African subsidiary Longyuan Mulilo operates at maximum efficiencies, requires a 24/7 schedule.

Andrew Doughty, the renewable energy farm’s safety manager, said maintenance work is shouldered by a team of 10.

“Oil and gearboxes needs to be checked regularly and each turbine has a routine annual service that takes about a day,” he said. The transformers and isolators on the 2,000 poles supporting a 168km overhead line network connecting the turbines to the substation also demand routine inspection and technical testing.

Replacing a wind turbine’s 36-ton gearbox can take several days, discounting delays caused by high winds, and emphasises the importance of rigorous and cost-effective maintenance duties.

Various meteorological data is monitored and analysed at the wind farm’s operations centre, tracking and predicting wind direction and speed, while assessing humidity and barometric pressure that can impact the performance of the three blades, each weighing six tons.

During the Northern Cape’s summer months monitoring electrical storm movements is crucial to prevent death or injury to maintenance crews and damage to the wind turbines from lightning strikes.

The wind turbines perched on De Aar’s surrounding mountain ridges are easy targets for lightning strikes. Wind turbines are fitted with lightning protection systems (LPS) and earthed to limit any damage to the R10m turbines. However, LPS reliability and protection is impaired after a strike.

“Lightning is our biggest risk. If a turbine is struck, you have to replace fuses and surge protectors. You can run it. But without replacing the protection it risks damage to the turbine from another lightening storm,” Doughty said.