When designing turbine shaft guarding for hydroelectric dams, there are numerous challenges of size, space and simplicity that must be addressed. Although these aren’t exactly new challenges for Machine Guard & Cover Company, since we regularly work in environments where floor space is at a premium, some projects can still be daunting. We were approached to build guards for turbines with shafts three and a half feet in diameter and over twelve feet tall. In addition to the size of the turbine shafts, the additional challenge of the turbine pit had to be addressed. The pits house not only the base of the turbine but a variety of gauges and instruments used to measure the status of the turbine and dam infrastructure. This means that regular access by dam employees was essential.
When in the bottom of the turbine pit, those checking equipment or performing maintenance were in close proximity to the exposed shaft. Regular high water levels and demand for output meant that shutting down turbines for servicing was not an option. Potentially exposing employees to a four-foot diameter shaft, spinning at ninety revolutions per minute, in a location where someone could easily become stuck between the walls of the pit and the turbine shaft was an obvious and unwanted hazard that had to be resolved.
Plastic for Turbine Shaft Guarding
Machine Guard & Cover Company’s solution was an assembly of thermoformed shaft covers, supported by a framework of extruded aluminum. Using these materials meant that assembly was simple and the final construction was very light weight. Kydex plastic is used when insulation from electricity and flame resistance is required. This means that this material is required for use in hydroelectric dams. Machine Guard uses Kydex plastic for all of its turbine shaft guarding projects. This particularly large project was no exception. Thanks to the Kydex plastic, all of the thermoformed parts in this application are electrically insulated and fire resistant.
Lightweight, Rigid Turbine Shaft Guard
The entire assembly is modular, meaning that a group of just two or three individuals can assemble the guard structure, and the use of captured fasteners and rivet nuts means that no special tools are required for installation. Since the shaft cover is supported by the aluminum framework, only a few C-clamps were required to hold the base of the guard in place. This eliminates the need for any risky modification of the turbine’s bearing housing. When making the custom shaft guard, the curve and ribbing formed into the Kydex meant that despite the lightweight construction, the shaft guard’s structure was ridged enough to prevent any contact with the shaft if someone were to fall or lean against the guard itself.
With the final guards in place, employees can now access the bottom of the turbine pit to gather essential information about the turbine’s status and perform regular maintenance in the turbine pit, without shutting down the entire turbine system. This saves time, resources and costs for the dam and prevents any potential workplace injury.