Thus, in 1967, the Elprom Group included 20 works, one research institute and 6 technological development centers at some of the works. And while in 1947 the Bulgarian electrical equipment industry met only 0.65% of the needs of the country, in 1967 it met already more than 90°/o of the demand, and constituted about 20% of the total machine building in the country.

Electric motors are among the most important items in the production range of the High Voltage Equipment Works in Sofia. The Works recruited young electrical engineers among the first graduates of the State Technical University many of whom were holders of bursaries from Elprom. Young and ambitious, they joined the older and more experienced engineers in the fulfillment of the Works Programs. Later on, many of these engineers became ranking decision makers, highly qualified teachers, scientists, designers and technologists.

As early as 1949, a package of technical documentation on a new developed series of general-purpose asynchronous low-voltage electric motors types "A" and "AO" of 10 kW or less for direct connection to the mains was received from the Soviet Union. With a view to the limited capacity of the Bulgarian electric power system, they had to be designed for indirect start, i.e. through star- delta switches. A Bulgarian series of electric motors of a new design-AM, and later on, AP and AOP, was developed. The Bulgarian designers developed more powerful asynchronous motors up to 100 kW (1951-1956).

Within the period 1956-1958 the Bulgarian specialists created AO electric motors of an ingenious design with considerably smaller overall dimensions permitting saving of non-ferrous metals thanks to the better quality of the materials used, especially the enamel for conductor insulation and the rotor groove size. Thus the weight of the motors was reduced by about 30%. That motor design was adopted for manufactures from the COMECON-Eastern Europe.

The Apparatus Factory in Plovdiv which became an independent unit in 1952, developed and manufactured various types of automatic low-voltage circuit breakers, ballasts for fluorescent lamps, automotive switches and a number of other related products.

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