Topeka ? The Kansas Corporation Commission filed a complaint Wednesday with federal utility regulators accusing Westar Energy of charging unjust and unreasonable rates for electric transmission.

The cost of transmission is one part of the overall cost of electricity that is built into customers’ monthly utility bills. Like the cost of generating electricity, it is based on a formula that is directly passed on to consumers.

The complaint, filed with the Federal Energy Regulatory Commission, specifically challenges the “return on equity,” or ROE, portion of Westar’s rates, which is essentially the profit margin they are allowed to make on their investment. The complaint says Westar is currently charging 11.3 percent, which state regulators allege is too high given today’s low interest rates.

“We appreciate the role the KCC has in balancing the public interest, but in this matter we just have to agree to disagree,” Westar CEO Mark Ruelle said. “We trust the process FERC has to review such concerns.”

Ruelle said that FERC put rules in place about 10 years ago, at the direction of Congress, to attract more investment in the nation’s power grid because development had stagnated.

“We don’t have to go back far in history to see a period where Kansas and the nation were under-investing in this critical high-voltage transmission infrastructure,” Ruelle said. “Our concern is that the KCC’s efforts might cause Kansas to fall behind.”

The KCC said it has asked Westar to voluntarily lower its ROE on transmission to 9.37 percent to reflect the lower cost of capital available, but Westar has refused.

The difference would amount to about $15.8 million in revenue for Westar, but KCC said that amount is expected to double over the next five years because of expected utility growth.

KCC is asking the federal agency either to rule that Westar’s transmission rates are unreasonable and set a date for a hearing and settlement or initiate an alternate proceeding to reduce Westar’s transmission formula rate.