July 10th, 2013
I guess today is Tesla’s birthday from some of the posts on the internet. Having been a fan before all of the pop hype, I felt that I should write something.
Dealing with large electrical motors and their designs, I started to become interested in the design of the slip (induction) motor designs in the 1980s. It seemed so elegant even around a century after invention. That, of course, led me to read a little bit about the inventor when I discovered Mr. Tesla.
To digress a little bit, an induction motor was quite novel at the time. Motors at that time required brushes to bring electricity to the rotor (part that turns) and create a magnetic field. The stator (coils in the housing) would create a magnetic field and kind of always relatively the same at least with respect to the rotor. Tesla decided to change that and make the magnetic field rotate in the stator using three (3) phase alternating current (AC). Not only that, he was able to get rid of the brushes and use the rotating field to induce current into the rotor to create a magnetic field which interacted with the rotating field to cause the rotor to spin. It is a very elegant idea and quite an interesting control system as the loaded motor slows down but then the relative speed causes more torque to bring it back. This system also gets rid of the brushes which saves quite a bit on maintenance. About the only drawback is that it is not a constant speed under varying loads. With solid state electronics today, we can compensate for that, though. They could back then if they had control over the generator speed.
I will just recant some things that I learned about him over the years:
1) Edison was a sort of hero to Tesla. Tesla finally got to go visit him around 1884 and Edison gave him some work on the spot. Later Edison promised him $50k to increase the efficiency of Edison’s generators. Tesla worked hard and finished the work in a few months since he wanted the money for a research lab. Edison said that the $50k was a joke. Tesla quit and that was the end of his views of Edison as a hero (I think it ended earlier as he got to know the man). Tesla was pro-AC and Edison was pro-DC (direct current). This later led to the “War Of The Currents”
2) War Of The Currents: Edison had an established DC power infrastructure in place in NYC. Tesla’s ideas jeopardized his business and so Edison instigated public sentiment against AC by having a “road show” go around and electrocute animals to show the dangers of AC. I saw a video from the time showing an Elephant being shocked to death. AC was superior to DC in that it could be stepped up/down in voltage for efficient long distance transmission so was a threat to Edison’s business especially when Tesla was hired to consult on the Niagara Falls Power Project (hydroelectric) which could send power all the way to NYC. Edison also recommended AC to be used for the first execution using electricity which failed miserably and made Edison look bad. Side Note: I was able to see inside the old generator building on a visit to Niagara. It was closed but there was an open door so I got to look around for a bit undisturbed and got a real feel for the history and time.
3) Wireless Power Transmission (WPT): Tesla was fascinated by resonance and was alleged to cause a building to sway one time by a mechanical device that tapped on a support for days at the resonant frequency of the building slowly building up a resonance. His “Tesla Coil” design is an auto transformer tuned to resonance. With this, one can build up large electric fields and that is where the “lightning” discharges come from. His coil design enabled his wireless power transmission theory based on his calculations for the resonant frequency of the earth (later discovered by the US Navy in the 1950s and known as the Tesla-Schumann cavity resonance). He found investors and setup a lab near Colorado Springs because he enjoyed the natural lightning activity there. It is alleged that he was able to wirelessly illuminate about 200 light bulbs about 26 miles away. His investors seemed to have “pulled the plug” on his project when they realized that they could not charge for power. It was a good idea but there is too much power lost even if we decided to provide electricity in a socialistic way. In addition, there may be other effects such as increased risk of cancer (power lines are alleged to cause Leukemia for those exposed for a long time) and on the environment. Side Note: Around 1993 I found a museum in Colorado Springs with many artifacts from Tesla. Later in 2004 I went back and it had all been taken. I think they said it was all transferred to a museum in Croatia for him.
4) Radio: Tesla actually filed a patent for a radio in 1887 and was granted a few months before Marconi in late 1900. But, even though Marconi’s patent claims were rejected because of Tesla’s, the Marconi Wireless Telegraph Company was created in Britain backed by Edison and Andrew Carnegie and American Marconi was later created. For no reason, in 1904 the US Patent Office reversed their decision and gave Marconi the patent for invention of the radio. Marconi won the Nobel Prize in 1911 and Tesla sued but did not have the money to pursue. When Marconi later sued the government and in 1943 the US Supreme Court upheld Tesla’s initial claims a few months after he died. Interesting Article
5) Other inventions: Remote controlled boats and plasma weapons just to name a couple.
Ronald Kollman – RF Hardware Designer and President of Haynes-Bent, Inc.
Haynes-Bent, Inc. – Radiofrequency (RF) hardware design, EMC/EMI analysis and 3D Electromagnetic simulation. We also provide Technology advise for investors and executives.
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