Virginia Electric & Power Co. and Potomac Electric Power Co. reported increased earnings yesterday.

Vepco had profits of $275 million ($1.98 a share) for the 12 months ending Oct. 31, compared with $236 million ($1.77) for the 12-month period a year ago. Operating revenues grew to $2.35 billion for 12 months, compared with $2.11 billion last year.

Through Oct. 31, Vepco has earned $222 million ($1.57), compared with $185 million ($1.35) in the similar period last year. Revenues in that time grew to $1.96 billion from $1.77 billion. During the month of October, Vepco recorded income of $2 million -- a noncash allowance for construction funds on North Anna Unit 3. Vepco has recommended construction on Unit 3 of its nuclear power station cease.

Pepco's profits for 12 months increased to $116.8 million ($2.24), compared with $104.7 million ($2.03) in the similar period last year. Revenues increased to $1.08 billion from $983 million.

For the first 10 months of 1982, Pepco posted profits of $102.7 million ($1.98), compared with $95.6 million ($1.88) last year. Revenues grew to $939.7 million from $856.7 million.

Input Business Machines Inc. of Frederick posted increased nine-month revenues of $3.2 million compared with $2.6 million a year earlier, but the company suffered a $233,460 loss, compared with earnings of $209,034 (12 cents) last year.

In the third quarter, Input lost $48,283, compared with profits of $87,817 (4 cents) last year. Revenues grew to $1 million from $891,426.