Case Studies

Hydro Power Provider Saves Millions, Extends Equipment Service Life with Help from Timken Power Systems

The Primary Challenge

A U.S. renewable energy provider with 135 hydropower stations wanted to upgrade and repair a Francis hydroelectric turbine in one of its facilities. The location needed to partner with a technical expert that could clean, test, and recommend repairs for an aging hydroelectric generator connected to the turbine. Originally installed in 1923, the generator had helped the facility turn water from the Oswego River – the second largest flowing into Lake Ontario – into electricity for 100 years without ever being rebuilt. The facility’s maintenance team requested that Timken Power Systems (TPS) inspect the unit to determine the best cleaning method. Based on the type of dirt buildup, TPS recommended dry ice blasting as a non-abrasive, non-conductive, and environmentally-friendly alternative to chemical cleaning. During the cleaning, TPS experts uncovered extremely brittle windings with bare copper visible in some places.

“We immediately brought it to the customers’ attention,” said Glenn Stevens, Onsite Technical Services field technician for Philadelphia Gear, a part of Timken Power Systems. “It was apparent that, at the very least, the generator needed rewinding in order to be serviceable again. And the winding connections were difficult to access because they were located at the bottom of the unit.”

During a later stator iron test, it was determined that the generator’s stator frame was in good condition, but the stator core laminations were compromised. These laminations form rings around the stator to provide support and magnetic insulation that prevents electrical loss, reduces vibration, and lowers noise during operation. Nearly 30,000 pieces of core iron were removed and replaced with redesigned laminations to a full three hundred sixty degree design in place of the old semi-circular configuration which significantly reduced the number of joints where dirt, debris, and water could collect and lead to rust and other damage.

The Solution

Repairs to the 18 ft. wide, 50,000 lb. generator needed to be made without interrupting the power supply to thousands of homes and businesses. Over three months, TPS Onsite Technical Services (OTS) and Schulz Electric technicians worked at the customer location during a scheduled outage to make 90% of the necessary repairs. The total set of service solutions included:

Replacing old copper windings with new
Moving winding connections from the bottom to the top of the generator for easier inspection and maintenance
Design and installation of nearly 30,000 solid, one-piece laminations constructed using a silicon silicate-coated steel to eliminate joints where dirt, debris, and water enter
Installation of 12 resistance temperature detectors (RTDs), enabling maintenance crews to identify and correct potential hot spots before they cause generator damage
Refurbishment of the exciter package to improve the reliability of generator startups, completed at Timken Power Systems’ Smith Services’ industrial repair services facility in Princeton, W.Va.

Key Results

Repairing the existing generator cost a small fraction of purchasing a new unit. Engineering services alone could have cost up to $500,000 for a new design that could be retrofitted into the existing turbine system. The repairs were completed in time with no power disruption to customers.

“The refurbished, upgraded generator will provide many more decades of reliable services with the proper maintenance. We couldn’t have done it without the help of Barry Allen, our Onsite Technical Services subject matter expert on the motor side,” Stevens said. “Few providers have the breadth of capabilities we have. We were able to leverage our network of facilities in the Timken Power Systems’ network and provide the expertise of both Schulz Electric and Smith Services to deliver the most cost-effective, long-lasting solution for our customer.”