Virginia Electric and Power Co. appointed a new chairman yesterday and issued an earnings report that indicated the new chief executive's assignment will necessarily include boosting Vepco's profits.

Named to run the big Richmond based utility that serves most of Washington's Virginia suburbs was T. Justin Moore Jr., 53 who since January has been training for the post by serving as vice chairman.

Moore succeeds John M. McGurn, 65, chairman since 1971, who will continue to serve on Vepco's board directors.

At the same time, Vepco reported its earnings for the three months ended Sept. 30 fell from $61.3 million (67 cents per share) to $59.4 million (57 cents).

The per-share profits fell by a greater margin than the actual earnings because Vepco had issued about six million additional shares, raising the total number outstanding to 78.5 million.

Because of that dilution, Vepco's earnings pers share for the nine months ended Sept. 30 and for the 12 months through the same date remained unchanged - $1.93 for the year and $1.49 for the three quarters - despite increases in total earnings.

For the nine months Vepco's profits increased to $158 million from $144 million and for the 12-month period the utility earned $204 million, up from $185 million.

Vepco said its operating revenues were up in all three reporting periods: to $404.7 million from $387 million for the three months, to $1.13 billion from $1.03 billion for the nine months and to $1.45 billion from $1.31 billion for the year.

Vepco also said yesterday it has added two members to the board of directors, James F. Betts, 46, of Richmond and Milton L. Drewer, 55, of Arlington.

Betts, president of The Life Insurance Co. of Virginia, succeeds E. Claiborne Robins of Richmond, who retired after serving on Vepco's board since 1965.

Drewer, president of First American Bank of Virginia, succeeds Ashton C. Jones Jr. oa Arlington, a Vepco board member since 1969.

Moore, an attorney, began the climb to the top job at Vepco as an assistant general counsel for the company in 1956. He became senior vice president and principal financial officer in 1967 and in 1970 was named president and appointed to the board of directors.