After the incident NWP took all 66 two-bladed WEG machines at its two Welsh wind farms and at Cold Northcott in Cornwall out of operation. At Cold Northcott, one turbine lost its blades in a separate incident which NWP says is unrelated to the problems at Cemmaes (Windpower Monthly, January 1994). Investigations into the cause of the pitch-linkage damage still continue. The company has asked for independent scrutiny by a firm of consultants which is carrying out laboratory tests to identify why the machines failures. NWP's David Lindley says it looks as if there is a common factor to the damage on all the turbines. "There was a fairly complicated sequence of events which caused various things to go wrong," he says. "Ironically, it was not a failure of the rotor blades themselves which are designed to withstand winds exceeding 70 m/s." But essentially "very extreme loads on the mechanics and linkages led to component failure in the pitch link system."
He claims that during the storms wind speeds exceeded 55 m/s. "No turbines so far in Europe have been exposed to winds of this strength," says Lindley "From now on we will carefully scrutinise all turbines with an eye to this type of experience." Repairs are now underway and Lindley expected to see the first turbines recommence operation in late January. The rest will return to service in a phased way until mid-May when all turbines are expected to be back in operation. While the turbines are out of action, loss of electricity sales is costing around £700,000 each month. Lindley says that the cost of repairs and loss of revenue exceeded £1 million at the end of the first month after the shutdown of all three wind farms.
Manufacturer of the machines, the Wind Energy Group, says it is unable to comment on the problem for the time being due to a contractual agreement with NWP.