Nov. 1--The worldwide economic slump is taking its toll on Cape Ann's largest private-sector employer.

Varian Semiconductor Equipment Associates has laid off nearly 500 workers over the last 14 months and is now expected to delay construction of two wind turbines at its Blackburn Industrial Park plant.

The layoffs include an unspecified number of cuts made in October, after the Gloucester-based company had already reduced its worldwide workforce to 1,739 employees in September of this year from a high mark of 2,006 in September 2007.

Although company executives did not announce precisely how many workers were laid off last month, they told financial analysts in a teleconference Thursday that 25 percent of the workforce had been cut since October 2007, bringing the total number of employees down to around 1,500.

The majority of the cuts were in Varian's Gloucester manufacturing plant, which has slowed output considerably this year in response to declining sales of the company's tools for making computer chips.

As of September, around 1,200 Varian employees worked in Gloucester with another 100 at a training facility in Newburyport.

How long declining sales will delay the installation of the wind turbines, planned as the tallest in Massachusetts and capable of generating enough power cut into Varian's $2 million annual electric bill, is unknown.

When the city approved permits for the two towers last October, Varian officials said the windmills could be up and running within 16 months, but did not have a firm construction schedule.

The 30-story windmills would be built by a manufacturer now experiencing a backlog, and Bob Halliday, Varian's vice president and chief financial officer, said it is unclear how long it would take for the Varian windmills to hit production.

In addition to delay from the supplier, Halliday said the price of the units had gone up in the past year and Varian may wait until the economy improves before actually buying them.

"I think it is going to be delayed either by the backlog or the financial situation," Halliday said. "We are still positive about the project."

Varian, Gloucester's only publicly traded, locally-based company, makes equipment used to manufacture the microchips that go in computers, cell phones, video games and other products that require memory or computing.

The company's profits have grown steadily in recent years, but sales have slowed this year and slumped considerably as the national economy has slid into recession.

In the fourth quarter of its fiscal year, which ended Oct.