PEC Solutions Inc. said yesterday it had acquired AC Technologies Inc. for $46.7 million in cash plus $3 million in employee bonuses and payouts. Both companies are government contractors based in Fairfax.

The deal, which was completed yesterday, is PEC's fifth acquisition since it became a public company in April 2000 and its second purchase this year. In June it bought Integrated Information Technology Corp., a Denver satellite engineering firm.

"Above all we look for companies that have new clients, that are different, that . . . allow us to diversify our clients and build our business," said David C. Karlgaard, PEC's chief executive.

The purchase of privately held AC Technologies, which includes $16 million that will be used to retire debt, adds the U.S. Postal Service to PEC's list of customers. Eleven-year-old AC also counts the Department of Veterans Affairs and the National Institutes of Health among its biggest clients.

AC, which specializes in software development and network engineering, recorded $48.5 million in revenue during the 12 months ended July 31.

The addition of AC Technologies' 360 employees will push PEC Solutions' workforce to more than 1,750. No layoffs are expected as a result of the deal, and AC will keep its Fairfax headquarters. The company will operate as a wholly owned subsidiary within PEC's civilian government division, and Satya Akula, AC's chief executive, will stay on to lead the unit.

Karlgaard said PEC's appetite for acquisitions will remain strong in the months to come. "This year the pricing formulations look much more rational than they have over the past year or two," he said. "We still have liquid assets to support at least one additional acquisition in the next year or so."

Shares of PEC Solutions shed 11 cents yesterday to close at $10.10.

PEC Solutions chief executive David C. Karlgaard said his Fairfax company is in acquisition mode and has the money to buy another firm in the next year.