During 1956-1960 time period the transformer production extend increased.

They began to use grain oriented cold - rolled silicous steel sheet and products and subassemblies are typified. Transformer manufacturing takes place in separate halls allowing manufacturing transformers rated up to 20 MVA and 110 kV.

To proceed to 220 kV voltages, the construction of High Voltage Laboratory (HVL) and - at the same time - of Large Power Laboratory (LPL) began.

The transformer export began in 1955 and at that stage it tended to represent 20% of the production.

A production increase and diversification characterize the period between 1960-1965. Production surface had been enlarged; the license for 200 MVA/220 kV autotransformer was taken over.

The 190 MVA/220 kV transformer was accomplished and the license for the electric locomotive transformer was bought.

The stage 1965-1970 presents the same development of the production. Products of 400 kV could be achieved by means of new endowments; the new hall for welded constructions was built.

Within the stage 1970-1975 transformer manufacturing was re-organized by building the workshops for large power transformers construction and transferring the manufacturing of the distribution transformers up to 1600 kVA to a factory in Filiasi, a town near Craiova.

Thus, the 400 MVA transformer construction was allowed.

High Voltage Laboratory has been set in operation and at that time the Designing and Research Center detached from the Electroputere enterprise taking over H.V.L. and L.P.L.

Dry type transformer assimilation had begun.

After 1975 beginning with the Large Power Laboratory setting into operation, short-circuit tests started to be performed on the transformers; it was possible to test transformers as high as up to 80 MVA.

Transformer production was diversified, all the transformers required in our country for investments or to replace the importation ones being practically assimilated.

At the same time, the transformer demand on the foreign market increased, which leads to an increase of the export production, the latter being frequently above 40 per cent of the factory production.