Topeka ? Westar Energy is asking Kansas regulators to increase its electric rates by $20 million — the fourth increase requested this year by the Topeka utility.

Westar says the extra revenue would cover its investments in wind farms and a natural gas-fired power plant near Emporia.

Residential customers in Westar’s northern division would see their monthly electric bills rise by an average $1.43. In the southern division, the average monthly increase for residential customers would be 71 cents.

Westar had notified investors in April that it planned to seek the $20 million increase. The company has now made the request official with an application to the Kansas Corporation Commission.