After listening to an hour of arguments in Suffolk Superior Court yesterday from Harvard lawyers and from opponents of the University's Medical Area power plant project, Judge Roger Donahue took under advisement the opponents' request for a preliminary injunction to halt construction of the plant.

Judge Donahue will consider affidavits submitted by Harvard, power plant opponents and the Commonwealth of Massachusetts before announcing his decision, probably early next week.

In Violation

The groups bringing the suit, the Town of Brookline and the Brookline Citizens to Protect the Environment, allege that Harvard has continued to construct the diesel portion of the power plant in violation of the January 31 decision of the Massachusetts Department of Environmental Quality Engineering (DEQE), which disapproved the installation of diesels because of their projected emissions of nitrogen dioxide.

Thomas B. Bracken, attorney for the power plant opponents, offered three major pieces of evidence to support the groups' charge: an affidavit of a mechanical engineer stating Harvard has been working on the diesel electric generating portion of the plant since the state ruling; a series of letters from Harvard to Medical Area hospitals assuring them the power plant will supply electricity; and a recent advertisement in the Boston Globe for a utility power engineer who is qualified to operate diesels.

Robert W. Meserve, the University's attorney, argued that Harvard's recent work on the power plant is not in violation of the DEQE ruling.

John Desmond, the DEQE official responsible for overseeing the project, also swore in an affidavit that Harvard has not violated the state ruling.

Lawyers for the University as well as the attorney general of the Commonwealth will present motions to dismiss a second lawsuit in State Superior Court today--a charge brought by the selectmen of Brookline that Harvard should have been required to obtain a "certificate of need" before beginning to build the power plant, L. Edward Lashman, director of external projects, said yesterday.

Massachusetts law requires health care institutions to show clear need for any equipment or facility costing more than $100,000, but Harvard did not follow the certificate-of-need procedure because the Massachusetts Department of Public Health ruled in August 1975 that the plant did not require it, Lashman said.