Nikola Tesla

     If you ask any middle school student today who invented electricity, you are likely to get Benjamin Franklin or Thomas Edison as an answer.  If you ask who Nikola Tesla was, you are likely to get a puzzled look.  Many people don't realize that although Edison invented the light bulb, Tesla helped invent the means to effectively channel the electricity to power the light bulb.

     In the 1880's, Thomas Edison was using steam engines to generate and distribute 110 Volts of DC electric to power lights and motors in Manhattan.  DC (direct current) is an electrical circuit that has a constant voltage with current flowing in one direction.  The problem with this was that the location of the generator had to be within a few miles of where the power was being used, because power losses along the circuit caused significant voltage drops.  10 volts was an acceptable drop, therefore, the customer was receiving 100 volts.

     Nikola Tesla, an Austrian immigrant, arrived in New York City in 1884.  At the age of only 28, Nikola approached Thomas Edison with ideas that he had of electrical machines focusing on AC technology, that would help solve the problems at the time of power transmission and efficiency.  AC (alternating current) is an electrical circuit that has a varying voltage with current flowing in more than one direction.  Edison would not hear of AC and was interested only in ways to improve his DC distribution.

     Unlike Edison, Nikola Tesla was not a good businessman and lacked the necessary showmanship to promote his ideas.  However, a lecture that Tesla gave caught the eye of George Westinghouse, an industrial financier.  Tesla's contribution to the growing science of AC at the time was the invention of the polyphase induction motor, which could harness the cyclic energy produced by polyphase generators.  Among many others in the field, Tesla proposed how to transmit power over long distances without the power losses that was experienced on Edison's DC system.  To understand this, a quick lesson on electrical power is necessary.

     Power is the ability to do some kind work.  Electrical power is measured as the quantity of voltage and current.  A typical wall outlet in your house will provide 120 volts.  If a light bulb is connected and .5 amps is flowing through it, then the light bulb is utilizing 60 Watts (120 V * .5 A) of electrical power to keep it lit.  Typically, copper or aluminum have the ability to resist slightly the flow of current.  This resistance is a form of power consumption like the light bulb.  This power consumption is measured as the quantity of current squared and resistance.  Therefore, it would be more important to try reduce the current, rather than the resistance, to minimize power loss.  This is where Edison ran into trouble.  For him to reduce the resistance of his DC circuits, larger diameter of wire was necessary.  Of course, using more copper would only drive the cost up.

     Unlike DC, AC voltages can easily be converted from one magnitude to another through the use of the transformer.  A generator from a remote station could have its voltage stepped up to a very high magnitude to prepare for power flow along a transmission circuit.  Because of the power formula described above, a very high voltage would allow for a lower current.  As the transmission circuit got close to where the power was being used, the high voltage could be stepped down to a much lower voltage that would be safe for use.

     This clash of ideas over which technology was to be used to build the industrial might of the US as we know it became known as the War of the Currents.   As more people became aware of AC technology, Edison became very worried and went to the extreme of demonstrating the dangers of AC by performing public and gross electrocutions of animals.  When the State of New York mandated electrocution as a new method of capital punishment, it was rumored that Thomas Edison played a role in setting up the use of an old AC generator to provide the electric.  William Kemler was sentenced to death for murdering his wife.  He became the first person in US history to be electrocuted and is considered a casualty of the War of the Currents.

     In 1898, President Grover Cleveland flipped the switch to light the mass display of lighting at the World Fair in Chicago.  It was also known as the Columbian Exposition.  Westinghouse and Tesla won the rights to power the fair because they offered a bid that was half of the cost that Edison asked for.  This is where AC basically kicked off.

     Article by Dan Scrobe III