Chapter Corner

Olsson Industrial Electric: The Dalles Dam Station

General---The-Dalles-Dam-1_Revised.gifOlsson Industrial Electric was recognized for its work on a comprehensive modernization to the station service electrical distribution system at The Dalles Dam. The Dalles Dam is a 2,100 MW hydroelectric power generation facility that provides power to the Pacific Northwest. It is the fourth largest dam operated by the U.S. Army Corps of Engineers.

The three main purposes of the project were to upgrade the electronic control systems from the original 1950s installation, replace wire distribution to improve the quality of the cable infrastructure, and connect a secondary power source to create internal redundancy. These electrical upgrades improved turbine function control, power generation efficiency, and system reliability and serviceability.

The project featured a complete replacement of 4160V station service protective relaying and breaker controls, including a complete relay panel replacement without any interruption of service and the upgrade of all electromechanical relays to microprocessor-based relays.

Olsson also replaced the existing 13.8V to 4160V station service transformer with a new water cooled 5000kVA station service transformer and added an identical second 5000kVA transformer. The new transformer required significant concrete cutting to create a new transformer vault within the powerhouse structure as well as the addition of oil containment and HVAC.

Olsson_14.JPGOlsson used more than 3,000 feet of cable tray and tens of thousands of feet of rigid metal conduit designed and built to meet all seismic requirements and miles of medium-voltage cable and low-voltage cable.

One challenge of the project was that the dam could not be deactivated during the work because it is a significant source of power for the Pacific Northwest. Olsson worked for five years at a fully energized location without interrupting the facility's power production. Olsson accomplished this by constructing temporary power supplies that continued power production while the primary equipment was being upgraded. By following the Arc Flash Protection program and by maintaining strict safety standards, Olsson achieved a zero safety incident record during the project's five years.