Lifting solutions service provider Johnson Crane Hire recently completed an order for Jeffrey’s Bay wind farm in the Eastern Cape, in July, when a rotor from a wind turbine had to be removed to repair a damaged blade.
Each turbine comprises an 80-m-high tower, three 49 m blades, a nacelle with the generator and gearbox and a transformer box on the ground.
The Jeffrey’s Bay wind farm has 60 wind turbines spread over 3 700 ha. It can generate up to 138 MW of electricity when all its turbines are operating at full speed. The power is fed into a 132 kV transmission line from a substation built to State-owned utility Eskom's specifications.
Johnson Crane Hire deployed its Liebherr LTM 1750-9.1 (750 t) all terrain crane, for its client FairWind, for installation on the challenging project, which it added to its fleet towards the end of 2013, owing to an increased demand for specialist lifting in the local wind energy sector.
“We have had a number of enquiries for repairs to wind turbines in the Eastern Cape after completing the FairWind contract,” said Johnson Crane Hire key account manager Janet Barnes, adding that the company has already erected four wind generators at the Darling wind farm, in the Western Cape.
The scope of work included the removal of a rotor from a wind turbine for the purpose of repairing a damaged blade. The estimated time for repairs to the damaged blade was about seven days. However, strong winds delayed the repairs to the damaged blade, as well as the replacement of the rotor.
The weight of the hub and blades totalled 62.5 t and the height from ground level to the centre of the hub was 80 m. “The crane was configured with a main boom of 49.1 m, an insert of 19 m and a 28 m luffing section, totalling 96.1 m, enabling a hook height of 90.19 m,” explains Johnson Crane Hire heavy lift division manager Grant Parker.
He adds that the LTM 1750-9.1 is perfect for this application as it is able to move quickly between the various hard stand areas, owing to its ability to be set up and stripped fairly quickly.
The nine-axle crane has the advantage of its complete telescopic boom remaining attached during transportation on public roads. Its maximum lifting capacity is 750 t at a 3 m radius, while its operational weight is 108 t and its total counterweight is 204 t.
About John Crane Hire
Johnson Crane Hire operates across South Africa with a fleet of hydraulic and crawler cranes ranging from 8 t to 750 t on both short- and long-term projects. It works in conjunction with its customers to design optimum lifting solutions, ranging from supplying professional operators and full supervision to all necessary rigging equipment in a single source supplier approach.