Active Power, the electrical equipment vendor known best in the data center industry for its flywheel-based uninterrupted power supplies and containerized full back-up power solutions, has found a new permanent president and CEO four months after Jim Clishem stepped down from the position.

Doug Milner, the new CEO, comes to Active Power from Aquilex Corp., where he served as COO. Aquilex is a provider of maintenance solutions to the energy-services sector.

“Active Power is a leader in the continuous power and infrastructure markets with dedicated people, highly differentiated products and solutions, and a rich patent portfolio in place,” Milner said about his new employer.

“I look forward to working with our teams worldwide to build on past successes, but also identify ways we can improve execution and financial performance that ultimately leads to creation of value for our shareholders,” he added.

Milner replaces Jan Lindelow, who stepped in as interim CEO after Clishem resigned in October 2011. Lindelow will remain with Active Power as an independent director of its board.

Milner’s resume includes a past senior-leadership role at Exide Electronix, a UPS vendor that was subsequently renamed into Powerware and then bought by Eaton.

Active Power reported a drop in profits for 2011 from the preceding year, attributing it to an underperforming UPS business and shrinking margins on its solutions.

The company reported US$75.5m in sales for 2011 – up from about $65m in 2010. Net full-year losses grew from about $3.9m in 2010 to about $7m in 2011.