Seeking greater operating efficiency, Westinghouse Electric Corp. and the Swiss firm ABB Asea Brown Boveri plan joint ventures in their multibillion-dollar electric generation, transmission and distribution businesses. ``With the entrenched fixed costs and relative slow rate of growth in those industries, a partnership is the way to go,'' said Julian Manear, an analyst in Chicago for Pershing & Co. ``There's a sharing of resources, so you don't have a duplication.'' The two companies announced Tuesday that they had signed a memorandum of understanding to proceed. Westinghouse will have a 55 percent interest and ABB a 45 percent interest in each of two partnerships. ABB also will pay Westinghouse about $500 million. One partnership will make, sell and service steam turbines and generators for U.S. and Canadian utilities. The businesses have current annual sales of about $700 million and employ about 5,000 people. ``Generally, joint venturing is considered an alternative to divesting,'' said H.P. Smith of Smith Barney in New York. ``They take a business, cut it back as far as they can, then if it's still not meeting the goals, they consider'' selling it or finding a partner. Westinghouse's turbine business ``hasn't earned a lot of money for quite a number of years now. The market is depressed and will stay depressed,'' Smith said. The other partnership will involve transmission and distribution products, including transformers, meters, controls, and switchgear, now sold in the United States and Canada. The businesses have annual sales of about $1.4 billion and employ about 11,000 people. The partnership allows ABB to buy the transmission and distribution joint venture or Westinghouse to force the sale in 1990. Smith said Westinghouse improved its transmission and distribution equipment business ``to a point where it was making OK money, but still well below the corporate goals.'' In both cases, the partners will combine plants and engineering and marketing organizations in fully developed industries that show reduced growth potential. Manear said he does not expect wholesale employee layoffs or plant closings, but foresees delays in capital spending. John C. Marous, who became chairman and chief executive of Westinghouse in January, recently told securities analysts the company's goals for 1988 include sales growth of 8.5 percent and operating profit margins of at least 10 percent. Westinghouse recently announced joint ventures in factory automation with the West German electrical equipment giant Siemens A.G. Smith said the joint ventures under Marous ``are showing this new administration is not going to sit back and rest on the laurels'' of Westinghouse. ABB, headquartered in Zurich, was created Jan. 1 with the merger of Asea AB of Sweden and BBC Brown Boveri Ltd. of Switzerland. With sales of $18 billion and 180,000 employees worldwide, the company is one of the world leaders in electrical engineering. Westinghouse, based in Pittsburgh, had 1987 sales of $10.7 billion in electrical equipment, defense electronics, broadcasting and other businesses. The company employs about 110,000 workers.