A needle position feedback assembly prototype has been ordered for a test run in one of the Tyee Lake hydropower facility's two turbines. Sitting on top of the turbine nozzle restoring mechanism's control head, it reports the position of each nozzle via a sensor.
A prototype component to the turbines at Tyee Lake's hydroelectric facility will be put into use this summer.
A new needle position feedback assembly will be going into service, replacing the current models. Southeast Alaska Power Agency executive Trey Acteson explained the current assembly units have a tendency to leak, and are experiencing senor failures.
The needle position feedback assembly sits atop the control head of the turbine nozzle restoring mechanism, and is a critical part in controlling the amount of water directed into the turbine runner. This in turn controls the speed of the generator.
Each of the powerhouse's two turbines has six such assemblies. The new design will be an enclosed piston with fewer ports and using different seal technology.
"We'll run them for a few weeks," Acteson explained.
The prototypical design was put together by a consultant and SEAPA staff. If it works without any problems, 11 more will be manufactured and installed.
The change-out will coincide with planned maintenance to minimize disruption to service.
The project was penciled in to the 2017 fiscal year's renewal and replacement line item, and with a 16-percent contingency may cost $123,000.
In service since 1984, the Tyee Lake facility has been managed by SEAPA since operations were transferred from the defunct Thomas Bay Power Authority in 2014. The lake-tap facility is located at the head of Bradfield Canal, approximately 40 miles southeast of Wrangell and 70 miles southeast of Petersburg. It can produce 25 Megawatts of power, and has room for a third generator.
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