PRINCETON – The town’s Municipal Light Department Manager, Brian Allen, told commissioners at the Jan. 13 meeting that the north turbine (windmill) has been shut down due to a problem with the gearbox.
The turbine has been out of service for about three weeks.
Allen said PMLD crew members found the problem during a weekly inspection in December.
“The north turbine is non-functioning due to damage to the high speed synchro gear. The machine was running but not making any noise,” he said. “There is a large tooth in the gear that is missing that went someplace. The entire tooth is missing from the gear box. We don’t know if in the process that tooth got ground up and did more damage to anything else.”
The north turbine moves faster than the south turbine. They have the same type of gear box, but the north turbine’s is nearer to the back of the machine.
The gear box on the south turbine was in the front and made 22 rotations per minute, the high speed synchro gear on the north turbine makes 2,000 rotations per minute.
“The gear box is like a big transmission,” Allen explained.
In August, 2011, during a bi-annual maintenance oil change on the turbines, the PMLD crew discovered pieces of metal in the oil from the gearbox of the south turbine. The metal pieces found in the oil were from the teeth in the gear box that had been ground up, and those pieces settled in the bottom. One of the teeth broke off and broke other teeth, and once the gear box was opened it was determined that it needed to be replaced.
In 2012, a replacement gear box for the south turbine was found in Germany, rebuilt, tested, and shipped to Boston. The gearbox weighed approximately 37 tons and two cranes had to be used to make the repairs at the wind site. It took 12 tractor trailer trips to deliver parts for the 600 ton crane needed at the wind site to replace the failed gear box.
The gear box was under warranty, but it was discovered that PMLD was a third party to the warranty. In all, $900,000 was spent to replace the gear box and fund related costs, and according to Allen, PMLD never did get financial recovery from that incident. Along with being a third party to the warranty, Fuhrlaender, the German manufacturer of the wind turbines, the vendor that installed the equipment and another vendor involved in the installation, all went out of business.
“We did get an insurance settlement of approximately $265,000 that covered attorney’s fees and some other costs,” said Allen.
Last week, Allen said that representatives from R.M. Wilson in Wheeling, West Virginia, will be in Princeton later this month to do an exploratory evaluation of the turbine to see if they can repair it. Cost estimate for the exploratory work is $1,536, he said.
Wilson will look into the machine with a camera to determine whether the damage is isolated or whether the tooth sheared off and did more damage. The gear box with the missing tooth weighs 300 pounds, said Allen, and a crane would be needed to work on the turbine.
“We need equipment to remove the old part, and we also have to disconnect the generator, shaft distributer, and drain 275 gallons of oil, which in this cold weather is very thick, like molasses,” he said. “We can’t reuse the oil, so new oil has to be pumped back in and that overall could be expensive.”
The cost to replace the oil is about $5,000 and between $1,500 and $1,700 to put the oil in the turbine. Another vendor might have to be hired to replace the oil.
“We have no idea of the cost at this point. Hopefully, Wilson will have the gear box part in stock, but they have not worked on Fuhrlaender turbines, so they don’t know if their equipment will work on this turbine,” said Allen.
Allen said he wants to gather all the information and give the light commissioners an accurate number for repair.
PMLD installed the two 1.5-Megawatt Fuhrlaender wind turbines on 215-foot towers on Oct. 31, 2009. The turbines became fully operational on Jan. 14, 2010 and were expected to produce approximately 40 percent of the town’s annual energy requirements. The cost to install the two windmills was approximately $7.3 million and the windmills have an expected life span of 20-25 years. The remaining debt of approximately $6.1 million won’t be paid off until 2026.