Potomac Electric Power Co. yesterday raised its divided for the first time in three years as profits during 1976 increased sharply from the previous year.

Virginia Electric & Power Co. and Equitable Bancorporation reported higher profits for the final quarter of 1976. During the full year, however, Vepco's earnings-per-share fell and Equitable operating profits also declined.

Pepco, the most widely held Washington area stock, will pay a dividend of 32 cents a share on March 31 to stockholders of record Feb. 18. The electric utility had been paying 29 cents a share quarterly since the first quarter of 1974.

Chairman W. Reid Thompson said Pepco's profits last year totaled $77 million ($1.72 a share) compared with $55 million ($1.16) in 1975, when earnings were abnormally depressed. The company had earned $1.71 a share in 1973 and 1.63 in 1974. Revenues last year rose to $550 million from $493 million.

Thompson said that prior to the new dividend rate, Pepco's payouts had increased 9 per cent since 1968. 'It is essential that the owners of our business receive a reasonable return for the capital [invested] . . . Pepco experienced a severe earnings decline in 1975 and this dividend increase in overdue." Thompson said.

In another development, George Hyman Construction Co. presidena A. James Clark was elected to Pepco's board, succeeding Osby L. Weir, who died Oct. 6. Thompson said Pepco would benefit from Clark's experience given the utility's plans for $590 million of new construction in the 1977-79 period.

Vepco, a Richmond-based utility that supplies electricity throughout Northern Virginia, said fourth-quarter profits totaled $41.9 million (44 cents a share compared with $30.2 million (31 cents) for the same period in 1975 as revenues rose to $286 million from $242 million.

From the year, Vepco's earnings per share fell to $1.80 from $1.95 although total profits were up to $166.8 million from $154.7 million. The lower earnings per share reflect more common stock outstanding - an average of 68 million vs. 61 million. The utility's revenues rose to $1.1 billion from $1 billion.

Last month, the Virginia State Corporation Commission approved an 8.5 per cent rate increase for Vepco, which took effect Dec. 20 and is expected to increase the company's annual revenues by $66 million.

Equitable, a Baltimore holding company for Equitable Trust Co., Columbia Bank & Trust and Farmers and Merchants of Hagerstown and majority owner of University National Bank of Rockville, reported fourth-quarter operating profits of $2.37 million (68 cents a share) compared with $2.12 million (61 cents) a year earlier.

For the year, Equitable earned $8.8 million ($2.51 a share) before investment gains or losses compared with $8.9 million ($2.48) in 1975, with fewer shares outstanding in the recent year.

Chairman Owen Daly II said the banking firm's directors have decided to change the cash dividend policy and will boost the quarterly payout to 10 cents a share from 5 cents. The firm will not declare a stock dividend in 1977 but will review payout policies annually for both cash and stock dividends, he said.

The increased quarterly dividend will be distributed April 1 to stockholders of record March 15. The firm previously has combined cash payouts with stock dividends and Daly said the directors' main goal was to retain earnings for future growth.

Total assets reached a record high of $1.45 billion od Dec. 31, up 11.3 per cent in the past 12 months. Loan volume increase nearly 21 per cent - particularly in real estate and installment lending - to $902 million.