1. Edison's Pearl Street Station: About 85 Customers on the First Day in 1882
On September 4, 1882, the power station built by Edison’s company on Pearl Street in New York started supplying electricity. On the first day, there were about 85 customers and a total of about 400 light bulbs. [1]
The area this station served was about 0.65 square kilometers (about 0.25 square miles). Since this is a square with sides of about 800 meters (about 2,600 feet), you could walk from one end to the other in about 10 minutes. [1] The station sent out 110 volts of direct current (DC). DC is a system where electricity always flows in the same direction. [1] The question is: why was the range so limited?
2. Why Low-Voltage DC Loses Power Over Long Distances
The Pearl Street station used low voltage, which meant a large amount of power was lost while flowing through the wires. Because of this, the distance electricity could be sent economically was limited. As a result, DC power stations could only serve small, densely populated areas. [1]
This is somewhat like sending water through a long hose, where the force of the water drops along the way. However, since electricity and water are different, this comparison ends here. [1]
The key to solving this problem was whether the voltage could be changed. DC voltage cannot be easily raised or lowered. AC, however, can have its voltage changed relatively easily using a device called a transformer. [2] By raising the voltage for transmission and lowering it again where electricity is used, power can be transported from large, distant power stations. [2] DC was not "bad"; rather, the distance it could cover was short because voltage could not be changed easily at that time.
3. William Stanley's Test of AC and Transformers on a Town's Main Street
Could AC using voltage-changing transformers actually work in a town? William Stanley tested this. On March 20, 1886, AC electric lights using transformers were operating on Main Street in Great Barrington, Massachusetts. [3]
The system generated 500 volts, stepped it up to 3,000 volts for transmission, and then stepped it down to 100 volts using transformers in the basements of buildings. The wires reached about 20 businesses. [3] George Westinghouse provided the funding for this experiment. [4] It is said that when 500 volts was sent about 4,000 feet (about 1.2 kilometers), the loss was only about 2%. [4] Stanley himself stated that Westinghouse was surprised by the scale and novelty of this system, which led him to commit seriously to the field of AC. [4]
Nikola Tesla was not involved in this experiment. This point is often confused, so it is important to note. [3]
4. Why Edison Stuck with DC While Tesla Made an AC Motor
Edison considered low-voltage DC to be a safe system that could compete with gas lamps. He viewed high-voltage AC as dangerous and believed it would take years to make it safe. His views on safety were a major reason for supporting DC. [6]
Additionally, income from patent royalties for DC systems is cited as one reason for his attachment to it. However, this is only considered one of the reasons and does not determine his entire character. [7]
At that time, Nikola Tesla, who was from Serbia, moved to the United States in 1884. It is reported that he worked on improving dynamos at Edison’s company for a short time, but he left in less than a year. [5] Details about his employment vary in the records, so we will not go deeper here.
On May 16, 1888, Tesla gave a lecture at the American Institute of Electrical Engineers (AIEE) about a polyphase AC motor using a rotating magnetic field. He also obtained a patent for it that same year. Westinghouse acquired the rights to this patent in 1888. [5] With a motor that could run on AC, AC became a system useful not just for lighting but also for power.
5. How the 1893 Chicago World's Fair Compared the Costs of AC and DC
The 1893 World’s Columbian Exposition in Chicago became like a trade fair for new electrical technology. For the contract to light the fair with lamps, Westinghouse bid $399,000, which was lower than the $554,000 bid by GE (the side that proposed DC for this bid). Westinghouse won the contract. [2] [8] The difference was about $155,000, which is roughly 30% less than GE’s amount.
The fair was said to be lit by about 160,000 light bulbs. [8] The competitor in this bid was not Edison personally, but the GE company. The Edison-related company had merged with Thomson-Houston to form GE on April 15, 1892. [7] Therefore, calling this simply "Edison’s loss" is not accurate.
However, the amounts and the number of bulbs are based mainly on secondary sources. The details should be verified in original records if possible. [2] [8]
6. The Niagara Falls Power Plant Sending Electricity About 42 km to Buffalo
The Adams Power Plant, built near Niagara Falls, began operation on August 26, 1895. Ten 5,000-horsepower generators were fully in place by May 1900. [9] As a large-scale polyphase AC power station, it showed that high-voltage AC is suitable for long-distance transmission. [9]
In the early morning of November 16, 1896, electricity from Niagara reached Buffalo, about 26 miles (about 42 kilometers) away. [2] It is said that the two-phase electricity generated was converted to three-phase at 11,000 volts for transmission. [2] Compared to the 800 meters of Pearl Street, this is about 50 times the distance.
GE won the contract for the transmission equipment, so this was not a sole victory for Westinghouse. [2] GE also later adopted AC. [7] Thus, the "battle" between DC and AC was decided by the realities of distance and voltage.
7. Edison's Reported Admission of a Mistake and Where DC Is Still Used
In 1908, it is reported that Edison said to Stanley Jr.’s son, "Tell my father that I was wrong." [6] However, this is hearsay and cannot be considered a certain record.
Did DC disappear? No. DC is still used today in computers, LEDs, solar cells, and electric vehicles. [2] Furthermore, High-Voltage Direct Current (HVDC) is sometimes used for long-distance, high-capacity transmission, where losses can be smaller than AC depending on conditions. This is not a story of "DC beating AC," but rather that different systems are suitable for different conditions.
8. How to Find AC Adapters at Home and Read Their Labels
Look for the charger for your smartphone or the AC adapter for your computer at home. While unplugged from the outlet, read only the text written on the body. Do not take it apart. [2]
You will likely see "AC" (alternating current) in the "Input" field and "DC" (direct current) in the "Output" field. This shows the path: AC arrives at your home, but DC works inside the device.
If you want to read more, try opening the commemorative materials for the Pearl Street Station [1] or the explanation from the U.S. Department of Energy [2]. They are in English, but they include diagrams and dates.