UPDATE 1-Thai Ratchaburi sees revenue down on plant shutdown

* Expects lower H2 revenue than H1 due to maintenance, demand

* Investing 1 bln baht in wind power (Adds details, share price)

By Saranya Suksomkij

BANGKOK, Sept 24 (Reuters) - Thailand's Ratchaburi Electricity Generating Holding RATC.BK said on Thursday its second-half revenue would fall below the 3.9 billion baht ($116 million) it made in the first half due mainly to a maintenance shutdown plus relatively cool weather that reduced demand.

"There'll be a maintenance shutdown in the fourth quarter," Managing Director Noppol Milinthanggoon told reporters.

"Relatively cool weather (compared to the first half) will also limit people's power usage," Noppol said.

Ratchaburi and its 25 percent owned Ratchaburi Power were in talks with financial institutions to reduce interest expenses and the move should be completed by the end of this year, he said, adding it should help offset the fall in revenue resulting from plant shutdowns in the second half.

Ratchaburi, the country's largest private power producer, is spending 1 billion baht to invest in wind power as part of its plan to seek growth opportunities and boost capacity.

"We've started to invest in a wind power project with a 30 percent stakeholding," Noppol said. "We're now looking for the right location, either in the north or northeastern part of the country."

Such a project would have production capacity of 60 megawatts (MWs), he said.

Ratchaburi is 45 percent owned by the Electricity Generating Authority of Thailand, the country's sole power buyer, and 15 percent owned by Banpu BANP.BK, the top coal miner.

On Thursday, Ratchaburi shares closed down 1.95 percent at 37.75 baht, while the overall Thai market .SETI dipped 0.3 percent. ($1= 33.55 Baht) (Writing by Ploy Ten Kate; Editing by Alan Raybould)