SPRINGFIELD - Chicago-area electric company Commonwealth Edison filed a request to raise power rates Wednesday, and Ameren Corp. could do the same by the end of the year.

ComEd said it is seeking to offset the cost of repairing and modernizing its massive system.

The ComEd request for an average of $6 more per month on a $75 bill comes only months after utilities reached a settlement with lawmakers to pay out $1 billion in refunds to power customers across Illinois.

The company said it would ask to raise rates during those settlement talks, but some consumer advocates think they're asking for too much.

"We've seen no evidence that ComEd deserves a big rate increase from consumers," said David Kolata, spokesman for the Citizens Utility Board, a watchdog group.

Ameren also said during settlement talks that it planned to ask for more money. Spokesman Shelley Epstein said Wednesday that the company hasn't changed its plans.

"We're moving in that direction," said Epstein, who added the company will file for the increase in November. He said Ameren's goal was to increase bills less than 10 percent.

Electric rates spiked Jan. 1, causing outcries from Ameren and ComEd customers across the state. Central and Southern Illinois Ameren customers who heat their homes with electricity were the hardest hit. For some, power bills doubled.

That led to more than half a year of wrangling between lawmakers and the utility companies. The $1 billion settlement was the result, with Ameren customers getting refund checks within the past several weeks.

Before either Ameren or ComEd could get another increase, it would have to be approved by the Illinois Commerce Commission. The commission often doesn't give companies the full amount requested, and the process of implementing the hike could take a year.

That means the price change ComEd asked for Wednesday isn't imminent, and an Ameren one likely would be further off.

ComEd, a subsidiary of Chicago-based Exelon Corp., provides electricity to 3.7 million customers across Northern Illinois.

Executives said they need the $360 million increase in delivery charges to offset upgrades to its system while coping with growing demands for service in the swelling Chicago suburbs.

State Rep. David Miller, D-Calumet City, said he didn't know if the costs ComEd requested were justified but hoped the Illinois Commerce Commission studies it closely.

"I hope they would hold the line on this," he said.

Mike Riopell can be reached at mike.riopell@lee.net or 789-0865.