AUMA SAV variable speed electric actuators optimise water flow through the dam system at Blackwater Reservoir near Kinlochleven, Scotland. The small Scottish town of Kinlochleven has an extraordinary claim to fame as the first place in the world in which every home was connected to electricity. That was courtesy of a 1907 hydroelectric dam project that generated power for an aluminium smelter near the town.

In the late 1960s the hydroelectric station was mothballed. Now the hydro plant with its ten Pelton turbines has been reinstated as a source of local green energy. Electricity generation has been boosted to 27.5 MW. During the redevelopment, several formerly manually operated penstocks were automated. Water flow control specialist Aquatic Control Engineering (ACE) chose AUMA variable speed electric actuators. These provide highly accurate flow control when opening and closing penstocks, increasing efficiency and reducing energy requirements. Maximum efficiency requires that the culvert supplying the hydroelectric station is operated almost full. The water level is measured by a sensor that signals the AUMA ACV intelligent actuator controls via a control panel. The AUMA actuator then drives the penstock open or closed.

Contributing to an economic operation
The variable speed actuators are configured to start and stop at low speed, increasing speed through the middle part of the actuation cycle. This reduces mechanical stress on the actuators and penstocks, and greatly reduces the motor inrush current compared with a high­-torque, full-speed start. As the generation plant operates 24/7 and the penstocks are ex­tremely remote, an uninterruptible power supply was installed to cover for any loss of power. Thanks to the low inrush current of the AUMA variable speed actuators, a rela­tively simple and small uninterruptible power supply could be used, significantly reducing the overall cost of the project. Water flows to the hydroelectric station ­through 6 km of concrete aqueduct and 2 km of steel pipe. In the early days, it was a full- time manual job to maintain ‘almost full’ flow through a box culvert at the power station end, with an ­operator remotely stationed to raise and lower the penstocks and keep them clean. This high labour requirement contributed to the plant becoming uneconomic and falling into disrepair. The new automated solution using AUMA electric actuators plays a big part in the economic operation of the power plant today.