ASME-Landmark:Hiwassee Dam Unit 2 Reversible Pump-Turbine

The Hiwassee dam and power plant on the Hiwassee River near Murphy, North Carolina, was built by TVA between 1936 to 1940 as a flood control and electrical generating facility. The initial power installation consisted of a single conventional Francis turbine driving a generator with a rating of 57,600 kW, placed in service in May 1940.

When studies were begun for the installation of a second generating unit in the late 1940s, installation of a pump-turbine was selected to provide additional generating capacity during periods of system daily peak loads, especially during the months of January through March which at that time corresponded to TVA's seasonal peak period. The Appalachia Reservoir, immediately downstream from Hiwassee, provided sufficient storage for approximately 27 hours of pumping with the pump-turbine. The Hiwassee pump-turbine was the first reversible pump-turbine built and installed in this country using wicket gates for control of turbine output power and improved pump efficiency. The unit also was much larger and more powerful than any reversible pump-turbine in service in the world at the time it went into operation.

The pump-turbine unit was installed and placed in operation in May 1956 after extensive commissioning tests. Performance tests for both pumping and generating operation were made in April 1957, using the Allen salt-velocity method for measuring discharge, and again in March 1958, utilizing the Appalachia reservoir for volumetric flow measurement. These tests showed that both the turbine guaranteed efficiency of 88.4 percent and pump guaranteed efficiency of 90.0 percent were met or exceeded. See ASME website for more information