Central Maine Power customers will see an increase in the delivery portion of their electricity bills beginning Friday, the result of several unrelated changes approved by federal and state utility regulators.

For a typical home customer, the delivery portion will rise by 7 percent. That will add $3.12 to an average bill of $78.47. The $3.12 figure assumes a household is using 550 kilowatt hours a month and receiving its energy supply from the state’s standard offer service.

The delivery rate hike will be more significant for large industrial customers, rising 38 percent. Smaller industrial customers and commercial businesses will see 19 percent increases.

The rate changes were part of a settlement agreement approved this month by the Maine Public Utilities Commission.

The largest share of the increase is related to the expiration of transmission cost refunds previously approved by the Federal Energy Regulatory Commission. Power transmission, as opposed to generation, typically is a larger part of the overall cost of electricity at factories and mills, said John Carroll, a CMP spokesman, which is why delivery rates are going up more steeply for those customers.

“For most of our customers, the change is about $3 a month,” he said. “The good news is, this reflects the predictable, stable rates we’ve had for the past 10 years.”

Other factors driving the delivery rate change include:

 Legal action against the federal government relating to spent fuel storage at the former Maine Yankee nuclear plant in Wiscasset resulted in millions of dollars in damage awards, which were given to customers. Those funds are now fully paid.

• Funding for Efficiency Maine Trust, which is assessed through utility bills, will more than double beginning Friday.