Topeka ? Westar Energy Inc. posted a large loss in the third quarter of this year, the result of a reduction in the value of a security alarm company it is trying to sell.

Westar said Monday it lost $81.3 million, or $1.11 per share, during the three months ending Sept. 30. For the same period in 2002, the company earned $43.3 million, or 60 cents per share.

For the first nine months of this year, Westar reported earnings of $70.4 million, or 96 cents per share. During the same period in 2002, the company reported a loss of $693.8 million, or $9.63 per share, because of a change in accounting rules that dropped the value of its 88 percent share in the Protection One security alarm firm.

During the third quarter of this year, Westar said, it wrote down the value of Protection One by $165.6 million. Officials said discussions with potential buyers convinced Westar that a previous appraisal of the business was too high.

“Protection One is performing a lot better today than it was performing two years ago, but it is still a business that it makes sense for us to dispose of,” said James Haines, Westar’s chief executive officer.

Westar’s earnings also suffered because of relatively mild weather during the quarter, which depressed revenues of its utility operations. Still, the company’s utility operations earned 78 cents per share, compared with 54 cents per share during the third quarter of 2002.

Under orders from state regulators to reduce its debt, Westar is trying to sell its nonutility assets, including its stake in Protection One, to raise funds. The company said Monday its debt had dropped to $2.9 billion by Sept. 30, from $3.6 billion at the beginning of the year.

Mark Ruelle, Westar’s chief financial officer, said Westar still expected to receive between $500 million and $650 million from selling Protection One. Westar hopes to sell its stake by early next year.