Following are capsule summaries of crucial Senate contests decided yesterday.

North Carolina

In a race viewed as a referendum on the politics of the New Right, Sen. Jesse A. Helms (R-N.C.) rode the support of white voters to a surprisingly comfortable victory over the popular Gov. James B. Hunt Jr. Approximately 87 percent of the state's Black voters supported Hunt, while Helms collected about 60 percent of the white vote.

Helms is now in line to become chairman of the Senate Foreign Relations Committee, since Sen. Charles H. Percy (R-III.) appeared headed for defeat.

Helms trailed Hunt by as much as 20 points early in the campaign, but he recovered by moderating his vitriolic rhetoric and aligning himself closely with President Reagan. Together the candidates spent close to $25 million and involved celebrities from all walks of life in the campaign.

Hunt's governorship was also won by a Republican, Rep. James G. Martin, only the second Republican to capture the statehouse in the last century.

Illinois

Percy, a moderate Republican, lost a tight race to five-term Rep. Paul Simon. Fait polls showed Simon captured some 90 percent of the Illinois Black vote and two-thirds of the votes of those describing themselves as "liberals."

Simon, aged 55, is a prolific author who has sponsored civil rights and environmental legislation. During the campaign he capitalized on Percy's apparent opportunism, saying the Senator had moderated his once-liberal stances to more closely match the President's.

With 78 percent of the precincts reporting at 1 45 this morning, Simon led Percy by 51 to 48 percent.

Tennessee

Rep Albert Gore Jr (D-Tenn) a fiscal moderate with a reputation for inventive positions on the environment and arms control, had little trouble in this race to replace retiring Senate majority leader Howard H. Baker Jr (R-Tenn.)

Running against former State Sen. Victor Ashe, Gore successfully went against the grain of Reagan's two-to-one victory in the Tennessee Presidential voting. He became one of three Democrats to wrest a Senate seat from the GOP.

New Hampshire

Sen. Gordon J. Humphrey (R-N.H.) benefited perhaps more than any other candidate from the Reagan coattail effect, winning reelection by a 15-point margin over five-term Democratic Rep. Norman E. D'Amours.

"We thought we could cut the coattails," D'Amours said last night. "We were unable to cut deeply enough."

Humphrey, a former airline pilot, overcame mild turbulence in his campaign two weeks ago, when his wife was linked to the American College of Orgonomy, a group that believes orgasms are essential to the physical and mental health of people of all ages.

The state's booming economy and the solid reelection of Republican Gov. John H. Sununu both helped Humphrey coast yesterday, despite late polls which said the race was still close.

Kentucky

In a major Republican upset, Mitch McConnell unseated two-term Democratic Sen. Walter D. Huddleston.

The moderate Huddleston, who had easily won reelection in 1978, supported most of President Reagan's economic initiatives during his term. But last night he fell to the unheralded McConnell, a popular judge who had long planned his assault on the Democrat in 1984.

Iowa

Rep. Tom Harkin. (D-Iowa), a traditional liberal, knocked off Sen. Roger W. Jepsen (R-Iowa) after a tightly fought and highly personal campaign.

The 45-year-old Harkin, a five-term veteran of the House, has closely identified himself with agricultural issues and won by consistently large margins in his heavily Republican home district. He capitalized on several major gaffes by Jepsen throughout the campaign.

Jepsen lost a large early lead in the polls in the late spring after disclosures that he reportedly belonged to an Iowa sex club. But a furious series of negative TV ads restored his lead by September, until Harkin retaliated with his own media blitz focusing on Jepsen's "insensitivity."