Tesla was one of the most brilliant inventors of all time. Before he walked off his job working for Thomas Edison, and before he started his own company and lost it to his investors, he conceived an idea for building an AC induction motor. At the time, there was no such thing. The Polyphase System
He first started thinking about the problem of building a brushless motor when his high school teacher first demonstrated a DC motor in one of his classes. Tesla was perceptive enough to realize its weak points — it was inefficient, and the commutator was prone to failure due to friction. When he pointed out those deficiencies and suggested that there might be a solution that didn’t involve a commutator, his teacher scoffed at him. But Tesla was unfazed, and the seeds of the solution began growing. Though it took him several years to work it out, he never gave up trying.
One day, out of the clear blue sky, it hit him. He conceptualized a rotating magnetic field that would push and pull a rotor around with it. Other people had been working on designing an alternating current motor, but his idea was unique. Instead of simply using an alternating current to drive the motor, he imagined two distinct circuits, each with an alternating current of the same frequency, but 180 degrees out of phase with each other. It was very close to what would eventually come to be known as a polyphase system. But it would be several years before he had the resources to fully develop it.
He carried around the idea in his mind during his years working as an electrician in Budapest and as an engineer in Paris. When he came to New York to work for Thomas Edison, he firmly believed that AC current was the future; however, Edison stubbornly clung to the idea of using DC. When Edison reneged on an agreement to pay Tesla a large bonus for improving the efficiency of Edison’s DC generators, Tesla promptly quit and, with investor backing, formed his own company. Tesla then felt he could concentrate on developing his AC motor and polyphase AC generators.
Over time, his investors decided that his ideas were ill conceived. They didn’t allow him the opportunity to build a working model, and they ousted him from his own company. After he lost the company, he was down, but not totally out. He found himself digging ditches, ironically, for the Edison company.
The Egg of Columbus
But during the time that he was doing manual labor, he kept trying to find a new backer to finance his dream of bringing polyphase AC and an AC induction motor to the world. After about a year, he got his chance. One of the people he was working with recognized his extraordinary mental abilities. He brought him to a financier who entertained the idea of speaking to Tesla about his project. But Tesla was unable to convince him that AC was the future.
Then Tesla had a thought.
“Remember the egg of Columbus?” he told
him. He was referring to the legendary story of how Christopher
Columbus defended his honor before a group of men who were maligning
his success. It was a dinner given for Columbus, and the jealous men
belittled his accomplishments.
“Anybody can sail across the ocean, and anybody can coast along the islands on the other side, just as you have done,” one of them said. “It is the simplest thing in the world.”
Columbus replied, “Who among you, gentlemen, can make an egg stand on end?” One by one they all tried and failed. They all agreed that it couldn’t be done.
Then Columbus took the egg and set it on its small end, gently breaking the shell in the process. With the new indentation the egg stood on its end.
“It is the simplest thing in the world. Anybody can do it…after he has been shown how!” Columbus remarked.
Tesla similarly challenged his potential financial backer. “What if I could make an egg stand on the pointed end without cracking the shell?” Tesla asked him. The man was intrigued enough to offer his help if Tesla could carry out this feat.
Tesla scurried off to find a hard-boiled egg and a blacksmith. The next day, he returned, copper-plated egg in hand. He produced a table, and be-neath it he fastened a toroidal iron core wound with four coils. The coils were attached to a two-phase AC generator. By driving a current through them, a magnetic field rotated around the toroid. When he placed the copper egg on the tabletop, not only did the magnetic attraction make it stand on end, but it also spun in synch with the rotating magnetic field. The moneyman was so impressed that, on the spot, he offered Tesla money to de-velop the AC induction motor.
Flowing Currents and Magnetic Fields
And that, in a nutshell, is why we use AC instead of DC for the vast majority of our electrical energy. Without electromagnetic induction, there would be no motors, no induction, no transformers, no alternating current, and we wouldn’t have to coil our excess feeder cable in a figure eight. Where there’s flowing current, there’s also a magnetic field — a key ingredient to many of the technologies we use in power generation and distri-bution. We don’t often think about it, but it’s as important as electrons and protons.
That day in New York City, Tesla put down his shovel and picked up his lab notebook. With the backer’s money, he set up the Tesla Electric Company. Over time, he patented the AC induction motor and an improved polyphase generator. He eventually sold the patents to George Westinghouse, and Westinghouse engineers perfected the designs with input from Tesla.
After a long struggle against Edison’s company, Westinghouse won the contract to supply the lighting for the World’s Fair in Chicago in 1893. A few years later, when Westinghouse installed the first centralized power generating system at Niagara Falls, the advantages of AC became unde-niable, even to staunch opponents like Edison, who began building his own AC systems.