Introduction
I will be exploring the contentious battle between Thomas Edison's direct current (DC) and Nikola Tesla's alternating current (AC) to become the dominant form of electricity distribution. This period in the late 1880s became known as the "war of the currents".
Edison initially had the upper hand with his DC system, but Tesla and his AC system eventually emerged victorious, changing the history of electricity distribution forever. Below, I will cover in detail the key events, innovations, and factors leading to AC defeating DC.
Edison's DC System
Thomas Edison pioneered the first electricity distribution system in the late 1870s using direct current. At the time, DC was the only feasible way to distribute electricity commercially.
Advantages of Direct Current
- DC electricity could be transmitted over short distances, making it suitable for downtown areas.
- DC systems provided steady, continuous flow of current in one direction. This made DC suitable for lighting as it produced a constant luminescence.
By the early 1880s, Edison had established his DC electricity distribution via coal-fired generators and copper wiring across downtown New York City.
Limitations of Direct Current
However, DC systems had major limitations:
- Power stations had to be within approximately 1 mile of the load as DC voltage dropped rapidly during transmission over long distances.
- DC could not easily change voltages with transformers. It required inefficient motor-generator sets.
These limitations meant DC systems could only cover small areas. To expand electrification, extremely expensive parallel direct current systems would be needed.
Tesla's Breakthrough with Alternating Current
In 1884, Serbian inventor Nikola Tesla emigrated to the United States to work with Thomas Edison. However, Tesla soon struck out on his own to develop his ideas for alternating current (AC) electricity distribution.
Key Advantages of Alternating Current
Tesla's AC system had two major revolutionary benefits compared to Edison's DC:
- AC voltage could be stepped up or down easily and efficiently using a device called a transformer. This meant AC electricity could be transmitted over vast distances with minimal power loss.
- AC motors ran more efficiently and were smaller than DC motors. This made AC systems more economical.
Tesla's Induction Motor
In 1888, Tesla patented his most important breakthrough - the induction motor. This polyphase AC motor ran on alternating current and had a simple, rugged design.
Crucially, it did not use brushes and could operate directly off high voltage AC power. This made it far more efficient and practical than DC motors.
The induction motor moved Tesla's AC system from theory to reality. Tesla secured backing from George Westinghouse to commercialize AC electricity distribution.
The "War of the Currents"
The emergence of Tesla's AC system directly threatened Edison's DC monopoly. A fierce rivalry erupted between the two camps, known as the "war of the currents".
Edison Spreads Fear about AC
Edison launched a propaganda campaign against the dangers of high voltage AC power, killing animals publically using AC electricity to try and scare the public.
However, AC was rapidly becoming the favored choice for central power stations and longer transmission thanks to transformers. In 1893, the Niagara Falls hydroelectric project chose AC transmission over DC, dealing a major blow to Edison's system.
Victory of AC at the 1893 Chicago World's Fair
The clinching victory for AC occurred when Westinghouse underbid Edison for the lighting contract at the 1893 Chicago World's Fair. Westinghouse lit the entire fair and its 200,000 incandescent bulbs using AC.
This high profile demonstration displayed AC's economical advantages. Within a few years, AC had become the universal standard for electricity distribution worldwide.
Why AC Beat DC
In summary, AC beat DC in the war of the currents because of its major technical and economic advantages:
- AC voltage could be changed easily using transformers, allowing national transmission over long distances.
- AC motors were superior and more efficient than DC motors.
- AC systems were simpler and cheaper than parallel DC systems covering large areas.
Legacy of the War of Currents
The widespread adoption of AC distribution enabled rapid national electrification and heralded the modern electric era. Despite losing the war of the currents, Edison's pioneering work with DC also played a crucial role in the early development of electricity supply networks.
However, it was Nikola Tesla's AC system that truly won the war of the currents and changed the world. AC allowed electricity to be transmitted anywhere, powering the electrification of homes, businesses, and industries across the United States and beyond. This system remains the standard for electricity distribution globally today.