Equitable Trust Co., Maryland's third largest bank, plans substantial expansion in the Washington market as part of a major consumer banking program announced last week.

Equitable officials said they expected the new program to give the firm a competitive edge over other banks as well as nonbanking competitors in its markets.

Although Equitable operates 26 branches in Montgomery and Prince George's counties, its presence in the Washington market is not as large as it would like, officials of the $1.9 billion institution said.

"We think that's the market where we're going to do a great deal of expanding," said John Brocato, senior vice president.

In fact, he added, Equitable will "put a great deal of emphasis" on adding market share in the D.C. suburbs as it develops the retail banking system outlined last week.

As part of its strategy, Equitable has adopted a new corporate identity by streamlining its name to Equitable Bank in all signature, marketing and promotional activities.

The key to Equitable's retail banking program is reorganization of its 116-branch network to provide more specialized services, coordinated with the bank's introduction of a new automatic teller system.

Under the new concept, Equitable's branches will be operated in a core-satellite arrangement, described by President J. William Middleton as the "retail banking delivery system of the future."

A more important consideration was pointed out by Equitable's chairman, H. Grant Hathaway: Rapidly increasing competition is forcing commercial banks to change banking procedures and marketing programs.

"Our traditional competitors from other banks, savings and loan associations and the major New York-based giants have been joined by a staggering array of fresh faces," Hathaway declared.

Competition from foreign banks, the investment banking community and nonbanking institutions such as Sears, Roebuck & Co. has "heated up to inferno temperatures," Hathaway added.

Against that background, Equitable began planning at least a year ago for a retail banking system that would increase market share, expedite service and cut costs. The idea is to distinguish two kinds of branches.

One kind is the core office, to be operated as a consultative center for trust and investment services, commercial banking and more complex customer needs.

The other, dubbed a satellite, will be equipped with a new generation of automatic teller machines ("Response" will replace "Harvey Wallbanker") but will offer limited assistance from bank personnel. Customers will be able to conduct basic banking transactions at the satellites, but the emphasis will be on electronic, self-service banking.

Automating its consumer banking, Equitable says, will broaden the opportunity for customers to bank by telephone, either at home or at satellites.

For the most part, existing branches are being converted into core offices or satellites. Eventually, satellites will take the form of free-standing kiosks, or they will be installed in retail stores, commuter depots or even restaurants.