The transmission systems of India developed in different ways depending on the growth and development of the generating facilities and the load centres. At the start of development where hydro power was the predominant source of energy long distance transmission lines were built to deliver power to load centres located far away. Thermal stations were located nearer to load centres and fuel transported to them. Hydropower development was pioneered in the Northern Region states of Uttar Pradesh and Punjab, in the Western Region state of Maharashtra and Karnataka and Tamil Nadu in the Southern Region. Interconnected power systems also developed without plan in an evolutionary manner. At the beginning interconnected systems were established to consolidate state resources into unified state grids. During the Fourth Five Year Plan (1969-1974) a start was initiated to interconnect the state grids into what are now the Regional Grids.
Growth in the transmission and distribution system has declined even more sharply than the growth of capacity and generation. By the end of 1993, India had 4.73 million circuit kilometres of transmission and distribution lines, only 0.09% more than the previous year. The rate of growth has been slow since the seventies, after rapid growth from a small base in the fifties and sixties. After growing by nearly 20% a year between 1950 and 1970, the rate dropped to 8% in the seventies, 6% in the eighties and now only 1% in the nineties. In 1994-95 the target for construction of new transmission line by the central and state governments was 4,606 circuit kilometres. By November 1994 only 2,752 kilometres had been completed. The targets set in the Plans have been low and even then they have rarely been achieved. In 1989 the Power Grid Corporation of India Ltd was established, to form a centrally owned and operated National Power Grid linking the regional grids.
