The history
From one New York block lit by DC in 1882 to a single 50 Hz grid tying all of India together.
The first electric lights ran on low-voltage DC, which could not travel much beyond a kilometre. Transformers, alternating current and three-phase systems changed that, and within twenty years power was crossing mountains and rivers at tens of thousands of volts, including in Mysore State. The twentieth century pushed voltages ever higher, and India stitched its state and regional grids into one of the largest synchronous grids in the world.
1882
Central power station
Thomas Edison, Pearl Street, New York
1891
Long-distance three-phase transmission
Lauffen–Frankfurt, Germany (175 km)
1897
Hydroelectric station in India
Sidrapong, Darjeeling
1954
Commercial HVDC link
Gotland, Sweden
1965
735 kV line
Hydro-Québec, Canada
2007
765 kV substation in India
Sipat, Chhattisgarh
2013
One synchronous national grid
India, via the Raichur–Solapur line
1882 – 1900
Edison’s low-voltage DC meets transformers and three-phase AC. Long lines at high voltage win.
1882
4 September 1882
Edison’s Pearl Street Station began supplying 110 V direct current to 82 customers and about 400 lamps in lower Manhattan. At such a low voltage the current was large, so it could only serve customers within about a mile before too much was lost in the copper.
Why it mattered. It started the electricity business, and showed why low voltage cannot travel far.
1882
September 1882
For an electricity exhibition in Munich, a steam-driven dynamo in Miesbach sent about 2 kV of direct current over 57 km of telegraph wire to drive a pump for an artificial waterfall. Most of the power was lost on the way, but it worked.
Why it mattered. It was the first long-distance transmission of electric power, and it pointed at high voltage.
1884
Gaulard and Gibbs showed their “secondary generator”, an early transformer, on a line of about 40 km between Lanzo and Turin. One alternating-current generator fed lamps along the whole route through transformers.
Why it mattered. Transformers let AC be sent at high voltage and stepped down safely, the idea every grid still uses.
1888
May 1888
Tesla patented a family of polyphase AC motors and generators, using several alternating currents out of step with each other to make a rotating magnetic field. George Westinghouse bought the patents.
Why it mattered. Polyphase AC gave the grid both efficient transmission and simple, rugged motors.
1889
3 June 1889
Power from a generator at Willamette Falls lit street lamps in Portland, about 14 miles (22 km) away, at around 4,000 volts. Sources differ on whether this first line was DC or AC; an AC line followed within a year.
Why it mattered. It was one of the first long-distance lines in America to carry power for paying customers.
1891
August 1891
A hydro plant at Lauffen sent about 300 horsepower of three-phase AC at around 15 kV to the electrical exhibition in Frankfurt, 175 km away. It lit a thousand lamps and drove an artificial waterfall, and about three quarters of the power arrived.
Why it mattered. It proved high-voltage three-phase AC could carry power efficiently over long distances.
1896
16 November 1896
Generators at the Adams power station, built to Tesla’s polyphase system, sent three-phase AC stepped up to 11,000 volts along a line about 26 miles (42 km) long to Buffalo.
Why it mattered. It settled the “war of the currents”: big AC power stations feeding distant cities became the model for the world.
1897 – 2013
From hill-town hydro stations to regional grids, then one national grid at 50 Hz.
1897
10 November 1897
A small hydroelectric station at Sidrapong, 12 km from Darjeeling, began supplying the hill town. Its two 65 kW generators were driven by water from mountain streams.
Why it mattered. It was the start of public hydroelectric power in India, and is often called the first in Asia.
1902
30 June 1902
A hydroelectric station at the Shivanasamudra falls on the Kaveri began sending power to the gold mines at Kolar, 147 km away. It was reported to run at about 30,000 volts, among the longest high-voltage lines in the world at the time.
Why it mattered. It showed that India could build long high-voltage lines, and it soon powered Bengaluru too.
1905
5 August 1905
Power from Shivanasamudra was extended to Bengaluru, which lit its streets with electricity. It is often described as one of the first cities in Asia to do so.
Why it mattered. Long lines from a big hydro plant began to change Indian cities.
1948
The Electricity (Supply) Act of 1948 set up State Electricity Boards to build power stations and lines in each state, with a central authority to plan the whole country. For decades each state and region ran its own grid.
Why it mattered. It began the planned electrification of India, one state grid at a time.
1989
23 October 1989
The central government formed the company now called Power Grid Corporation of India (POWERGRID) to build and run the inter-state high-voltage network.
Why it mattered. It gave India one owner for the lines that would tie the regional grids together.
1990
A ±500 kV DC line, 814 km long and able to carry 1,500 MW, linked the Rihand coal power station in Uttar Pradesh to Dadri near Delhi. Sources give 1990 or 1991 for its commissioning.
Why it mattered. It was India’s first commercial long-distance HVDC link.
1991
October 1991
The north-eastern and eastern regional grids were connected to run in step. The western grid joined them in March 2003 and the northern grid in August 2006, forming a “central grid” spanning most of the country.
Why it mattered. Step by step, separate regional grids became one synchronous machine.
2007
January 2007
India’s first 765 kV switchyard opened at the Sipat power station, and the first 765 kV lines and substation followed at Seoni. 765 kV is now the top AC voltage of India’s network.
Why it mattered. Each 765 kV line carries roughly as much as three or four 400 kV lines on a narrower corridor.
2012
27 January – 13 October 2012
POWERGRID and Indian equipment makers charged a national test station at 1,200 kV, stepping 400 kV up to 1,200 kV and back down through a short test line. A second phase was charged in March 2016.
Why it mattered. It tested ultra-high-voltage AC equipment made in India, including a 1,200 kV transformer from BHEL.
2012
30–31 July 2012
At 2:35 a.m. on 30 July an overloaded 400 kV line tripped and the northern grid collapsed. The next afternoon, northern, eastern and north-eastern India went dark together, affecting more than 600 million people in over 20 states.
Why it mattered. It led to tighter frequency rules, stronger links between regions and better protection.
2013
31 December 2013
A 765 kV line from Raichur to Solapur tied the southern grid to the rest of the country. From then on every big generator in India has turned in step at the same 50 Hz.
Why it mattered. India became one of the largest synchronous grids in the world, able to send power wherever it is short.
1950 – 1970
380 kV, 735 kV and the first HVDC links carry power hundreds of kilometres.
1952
Sweden brought hydro power from the far north to the south over a line of nearly 1,000 km at 380 kV, twice the voltage of earlier lines.
Why it mattered. The 380 to 400 kV class it began is still the backbone of grids in Europe and India.
1954
A 96 km undersea cable carried 20 MW of direct current at 100 kV to the island of Gotland, using mercury-arc valves to convert AC to DC and back.
Why it mattered. It began high-voltage DC, now used for the longest lines and most undersea cables.
1965
29 November 1965
Hydro-Québec switched on the world’s first 735 kV line, bringing power from the Manic-Outardes dams to Québec City and Montréal. One such line could do the work of about four at 315 kV.
Why it mattered. It opened the era of extra-high voltage above 700 kV, the class India later chose for 765 kV.
By the numbers
The highest voltage used for long-distance transmission, by year. Each step let one line carry more power, further, with less loss.
2014 – today
±800 kV DC links, 765 kV corridors and new lines for solar and wind.
2015
India began building new lines and substations to carry power from solar and wind farms to the grid: about 9,700 circuit km in the first phase, followed by a second phase approved in 2022.
Why it mattered. Renewable power is often made far from cities; without new lines it can’t be used.
2017
The first 3,000 MW of a ±800 kV DC link over 1,365 km was completed, carrying power from central India to the north. Later poles doubled it to 6,000 MW.
Why it mattered. Ultra-high-voltage DC lets India move huge blocks of power across the country with small losses.
2019
China opened a ±1,100 kV DC line more than 3,000 km long, able to carry about 12 GW, the highest voltage, longest distance and largest capacity of any link at the time.
Why it mattered. It shows how far DC can carry power, across a whole continent.
2020
September 2020
The first pole of a ±800 kV DC link from central India to Tamil Nadu went into service, about 1,800 km long. With both poles it can carry 6,000 MW, and it was later connected on to Kerala by a newer type of converter.
Why it mattered. It carries power from coal-rich central India to the south, far beyond the distance where AC would make sense.
2022
9 November 2022
The grid operator formed in 2009 as POSOCO, which runs the national and regional load despatch centres, was renamed Grid Controller of India (Grid-India).
Why it mattered. Its control rooms balance supply and demand across the whole country every minute of the day.
2026
14 January 2026
With a 628 km, 765 kV line from Bhadla to Sikar in Rajasthan, India’s network of lines at 220 kV and above passed 5 lakh (500,000) circuit kilometres.
Why it mattered. The network has grown by about 70 % since 2014, much of it to bring in solar and wind power.
Did you know?
A 765 kV line is about 3,300 times the voltage at your socket, yet a bird can sit on it safely because it touches only one wire.
Carrying 1 MW needs about 1.4 A at 400 kV but more than 4,000 A at 230 V.
On 31 July 2012 more than 600 million people in India lost power at once, the largest blackout on record.
The wires of a 400 m span can sag more than a metre further on a hot afternoon than on a cool morning.
Count the glass discs on a line’s insulator strings to guess its voltage: about 9 at 132 kV, 23 at 400 kV, 40 at 765 kV.
The people
1847 – 1931 · Inventor and businessman · USA
Built the first central power station, supplying low-voltage DC.
1850 – 1888 · Engineer · France
Co-inventor of an early transformer system for AC distribution.
1856 – 1943 · Inventor and engineer · Austrian Empire (now Croatia); worked in the USA
Patented polyphase AC motors and generators used at Niagara.
1846 – 1914 · Industrialist · USA
Backed AC and built the Niagara generators.
1855 – 1934 · Engineer · Germany
Organised the 1882 Munich and 1891 Frankfurt transmission demonstrations.
1862 – 1919 · Electrical engineer · Russian Empire; worked in Germany
Designed the three-phase machines for the Lauffen–Frankfurt line.
1845 – 1901 · Dewan of Mysore · India
Pushed through the Shivanasamudra hydro scheme that powered Kolar and Bengaluru.
1919 – 2001 · Engineer · Canada
Championed 735 kV transmission at Hydro-Québec.
Where it happened
Sources
Dates marked “c.” are approximate, and historians sometimes disagree about who was first. If you spot a mistake, tell us.
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