Three Phase Power

One extra wire allows transmission of triple the amount of electricity via three-phase power. With three wires rather than two, electrical operators can transmit triple the electricity. “Polyphase” is another term for three-phase power.

Three phase power usually transmits enormous amounts of electricity. These are the large transmission lines on tall polls. Electricity is converted into two-phase power, more practical for home use, at endpoint stations. Both heavy industry and electric cars use powerful three-phase induction engines.

Markedly, three phase power results in significant cost savings due to the reduced amount of wire needed.

Meters that regulated and measured the electricity spanned many patents. Eventually, Westinghouse acquired virtually all of them to compete with Edison, eventually lighting up the 1893 Chicago World’s Fair. Tesla’s patents proved to be the most valuable.

Alternators / Long-Distance Transmission of Electricity

Alternators and Alternating Current enabled the long-distance transmission of electricity. Edison’s electrical plant ran on DC which does not transmit far. Under Edison’s system, there were electric plants every few blocks in cities (the inner Chicago loop had 25 electric plants at one point). Tesla’s AC system transmitted electricity much further; it’s the same we use today at both power plants, transmission, and in homes and businesses.


There are two basic types of electricity, Direct Current (DC) and Alternating Current (AC).

DC current flows in one direction making it easier to work with and arguably less likely to electrocute people, two important factors for early electrical pioneers. Edison built his electrical plant and equipment using DC.

However, DC cannot be transmitted far without the electricity fading away. In the earliest days of electricity, where electrical plants were for businesses and wealthy people located in city centers, this hardly mattered. At one point, there were 25 electrical plants in the Chicago loop. Manhattan had electricity plants.

The European team ZBD had developed and patented an efficient an inexpensive method for AC generation and transmission. George Westinghouse, who had become wealthy innovating a better brake for trains but was hoping to move into the field of electricity, licensed the patent and went into business, competing against Edison’s DC plants (and patents). Another AC company was the Thomson-Houston Electric Company, that also relied on AC.

Tesla & Westinghouse

Westinghouse continued building AC plants and infrastructure and soon came across a young immigrant who had worked briefly for Edison then left to work on his own electrical innovations, Nicola Tesla. Tesla believed that AC electricity was far more practical than DC. He worked on innovating AC generators, transmitters, switches, appliances: everything required to build an AC electrical grid. He also built an AC motor, which electrical engineers at the time though impossible.

This brought about two competing electrical standards, AC and DC. Edison and Tesla each tried to sell their standard leading to the infamous “War of the Currents.” At one point, things ran so out of control that Edison, a capital punishment opponent, suggested New York State contact Westinghouse to build an AC electric chair, demonstrating the inherent danger of AC. Edison proposed using the term “Westinghoused” rather than electrocuted.

Centralized Electrical Plants

Over time, the benefits of a central large electrical plant became obvious (see: Insull). Generating electricity at one large central facility, then distributing it widely, is more efficient. Since this model did not work for DC, which could not be distributed more than a few kilometers, AC won out. Eventually, Thomson-Houston merged with Edison Electric company to form General Electric; the company focused on AC. Edison never showed up to work after the merger.

Today, AC electricity is what powers the houses and factories of the world though there are still limited largely low-voltage uses for DC electric. In any event, AC and DC are now largely interchangeable; while wall sockets are AC, computers, phones, tablets, and LED lamps run on DC power.

Induction Motors

“Intelligent people tend to have less friends than the average person.”

Nikola Tesla

There are two types of electricity, Direct Current (AC) and Alternating Current (AC).

Vastly simplifying, in DC electrical systems the current flows in one direction, like current in a stream. This makes designing certain appliances easier; the motor turns in the direction of the current much like a stream turns a water wheel. Spinning a motor or clicking a telegraph is relatively straightforward.

In AC the current flows both directions. The primary advantage over AC is current can travel much further than DC without a loss of power. However, turning a motor – harnessing the electricity do something useful – is more complicated. A water wheel if the current goes back and forth simultaneously is not all that useful.

Nikola Tesla worked briefly for Edison but quit. Westinghouse, the inventor of air brakes for trains, funded him. Among Tesla’s many inventions is a motor that uses AC electricity. Besides operating from long-distance electrical lines, the Tesla “induction” motors use magnetism and do not require brushes, which DC motors used to harness the electricity. This meant fewer moving parts and less friction, making them more powerful and longer lasting. Additionally, Tesla’s motors did not require inverters and started up immediately.

Almost all electric motors today are induction motors, including those that power electric cars.

Edison and others believed AC-based motors, like induction motors, were impossible.

Air Brakes

Air brakes use compressed air to allow trains to run much faster, reducing the cost of train rides. Before air brakes, train speeds were limited due to an inability to reliably slow them. Runaway trains were a real problem before air brakes limiting the speed and utility of trains.

Image result for early paris train breaking through a building

Westinghouse innovated an airbrake for trains that functioned vastly better than prior braking methods, which were sometimes ineffective and could cause trains to derail. His air brakes allowed trains to travel faster and more safely. They quickly became an industry standard.

The Westinghouse air brake used an air reservoir connected to brakes on each car. The momentum of the cars filled or removed air from the reservoir, slowing the train or allowing it to move faster. Unlike prior systems, the air brake was far more reliable and far less prone to break.

Air brakes clamp down when they are unengaged; the air pulls them away from the wheel rather than forcing them to slow wheels down. Because of this, in the event of a failure the brakes would clamp down slowing a train, rendering them failsafe. In the event of a catastrophic failure, the worse that would happen is a train wouldn’t move.

Earlier brakes were pneumatic but the systems leaked and were prone to failure. Whereas pneumatic fluid once leaked must be manually refilled, a challenge on countless rail cars, air is infinite.

Air brakes remain in use today for heavy equipment, especially equipment that is coupled. Some trains continue using air brakes though many have transitioned to electrical brakes that can apply more measured force. Air brakes are also used on semi-trailer trucks.

While the brakes are mechanically failsafe, human error can defeat them. If an engineer purposefully changes air pressure in the valves, the brakes can release when they should clamp. This happened in a 1988 Paris train accident which killed 56 and injured 60 people.

Later in life, Westinghouse decided to diversify and partnered with Tesla to build AC electricity.