A maintenance operation scheduled for this past March turned into an eight-month headache for officials at the Ames Electric Services Power Plant.

“During a planned major overhaul, the unit seven turbine generator would not operate properly,” said Brian Trower, assistant director of electric services.

The turbine has only functioned properly in tests once since June, and has cost the city a bundle of cash to fix.

Each of Ames’ four major turbines undergoes a major overhaul every five years, where the turbine is taken apart, piece by piece, and is checked for wear and tear. The electric services crew then rebuilds it and tries to get it as close to “as-new” as possible.

“A major overhaul is an expensive process. It’s not uncommon for a turbine generator overhaul to cost 750,000 to a million dollars,” Trower said.

However, during an overhaul in March, the crew found that the rotor, the part of the turbine that spins to generate electricity, was worn enough that it needed to be rewound, which is an expensive process.

“That was about $275,000. It’s fairly time consuming, also,” Trower said.

So the city shipped it off to a facility in Miami that rewound the rotor, and they received the rewound rotor in early June. However, upon reassembly of the turbine, they found that something was wrong.

“During startup, the generator produced excessive vibrations,” said Donald Kom, director of electric services. “We shut it down, and there was a lot of consulting about what to do next.”

They decided to send the rotor back to have it re-inspected. The results were not helpful.

“The facility in Miami couldn’t find anything wrong. We were caught; we knew something was wrong, but could not truly pinpoint it,” Trower said.

So they sent the rotor to an independent test facility in Richmond, Va. That facility tested the rotor and found that the rotor checked out electrically.

The power plant attempted to start the generator again on Halloween, but another issue popped up.

“It was internal to us, there was a mis-operation in the control room. The generator performed well,” Trower said.

The crew will attempt to restart the generator in the middle of this week. Trower said the generator has performed well, considering its age.

“This rotor is 40 years old. We don’t rewind them every five years; this is the first time we’ve had to rewind it,” he said.

Kom said he wants the generator up not only because of the obvious lack of power, but also the type of fuel that unit seven can burn.

“We have two generators in Ames that burn RDF, or refuse-derived fuel,” he said. “It’s a process where garbage, after being sorted and refined, is sent into our boiler. It supplements coal usage by 15 to 20 percent, reduces the amount of garbage sent to the landfills, and unit seven is one of the two that does this.”

Trower wants to get the unit back up as quickly as possible, and expects this week’s restart to be successful.

“During the summer, we had to buy power from other grids,” he said. “It’s typical to buy and sell power for economic reasons, but we had to buy it to cover the need of the city.”

“We are expecting this rotor to work now,” Trower said.