TBT: The History…and Science of the Electric Generator
Oh no! The power went out and you just finished filling your deep freeze with fudgsicles! You slam the freezer door shut hoping the power comes back on before your favorite dessert melts into packaged puddles. You check the fuse box; no blown fuses. You run outside to see if anyone else in the neighborhood has power. Nope, the whole area is in a blackout. Plus, your iphone battery died on the way back from the grocery store so you can’t even complain about the blackout to all your friends on facebook! And you were going to bake and decorate a cake for your food blog tonight and then invite some friends over to watch the game. Oh electricity! How we love and loathe you!!!
Electricity is probably the greatest discovery in all of history, however, we’ve become so dependent on it that it feels like we can’t survive without it. While saving your fudgsicles from impending doom and not being able to post about it on facebook is not a life or death scenario, owning a generator can mean the different between life and death for some people, especially those who live in rural areas with harsh winters. If the real scenario were that you live 20 miles from any town, in the middle of nowhere, in the middle of a record breaking winter and an ice storm comes rolling through, knocking out your power for days or even weeks, you better hope you own an electric generator or you might become a fudgsicle yourself.
What is an electric generator? How do they work? Who invented them?
An electric generator is actually called a dynamo and it is a machine used to convert mechanical energy into electrical energy. The modern-day generator works on the principle of electromagnetic induction discovered by Michael Faraday in 1831. Faraday discovered that the flow of electric charges could be induced by moving an electrical conductor, such as a wire that contains electric charges, in a magnetic field. To give credit where credit is due, American scientist Joseph Henry made that same discovery in 1831, however, Faraday was the first to publish his findings.
In 1827, Hungarian inventor, engineer, physicist, and Benedictine priest, Anyos Jedlik began experimenting with electromagnetic rotating devices which he called electromagnetic self-rotors. In his prototype of the single-pole electric starter, both the stationary and the revolving parts were electromagnetic. His dynamo used two electromagnets placed opposite to each other to induce the magnetic field around the rotor.
In 1832, French instrument maker Hippolyte Pixii built his dynamo based on the principles of Faraday’s findings. Pixii’s dynamo was a spinning magnet that was operated by a hand crank so that the North and South Poles passed over a coil that had an iron core. Pixii found that the spinning magnet produced a pulse of current in the wire each time a pole passed the coil. Since this device used a coil of wire, it produced spikes of electric current followed by no current, resulting in a low average power output.
In 1860, Italian physics professor Antonio Pacinotti became concerned with the spikes of current like that experienced in Pixii’s design. Pacinotti solved this problem around by replacing the spinning two-pole axial coil with a multi-pole toroidal coil. He accomplished this by wrapping an iron ring with a continuous winding, connected to the commutator at many equally spaced points around the ring and have the commutator divided into many segments. This meant that some part of the coil was continually passing by the magnets, smoothing out the current.
Werner von Siemens and Charles Wheatstone
On January 17, 1867 German inventor, Werner von Siemens and English scientist and inventor Charles Wheatstone simultaneously and independently announced their dynamo discoveries to the world. Siemens called his invention the “dynamo-electric machine,” but they both had created the same machine with only a few differences between them. The significant discover that they had both made was to use electromagnets rather than permanent magnets. This greatly increased the power output of the dynamo and enabled it for high power generation. This invention led directly to the first major industrial uses of electricity.
In 1871 Belgian electrical engineer Zénobe Gramme reinvented Pacinotti’s design by filling the space that occupied the magnetic field with heavy iron cores and minimizing the air gaps between the stationary and rotating parts. The Gramme dynamo was the first machine to generate commercial quantities of power for industry. The basic concept of a spinning, endless loop of wire remains at the heart of all modern dynamos. In 1873, Gramme noticed that the shaft of his dynamo began to spin when its terminals were connected to another dynamo producing electricity. Gramme had discovered that a dynamo can act as an electric motor.
In 1876, American inventor, entrepreneur and philanthropist Charles Brush invented the open coil dynamo that could produce a steady current of electricity. Brush started with Gramme’s basic design and improved it by making the ring armature shaped like a disc rather than a cylinder. The field of electromagnets were positioned on the sides of the armature disc rather than around the circumference. There were four electromagnets, two with North Pole shoes and two with South Pole shoes. The like poles opposed each other, one on each side of the disc armature.
It wouldn’t be a proper lesson in the history of electricity without mentioning Nikola Tesla. In 1884, Serbian-American inventor and engineer Nikola Tesla invented the electric alternator, an electric generator that produces alternating current. Until this time, electricity had been generated using direct current from batteries. Alternating current is far more efficient for sending electricity over long distances. 1888 Tesla demonstrated the first “polyphase,” an alternating current electrical system. His AC system including everything needed for electricity production and use: generator, transformers, transmission system, motor, and lights. George Westinghouse, the head of Westinghouse Electric Company, bought the patent rights to the AC system.
Today, giant electric generators run the power plants that supply most us of with the ability to flip on a light in a fraction of a second. Many people even own their own generators to be used as a backup in case the power goes out. There have been many more contributions to the science of electricity and generators since the 19th century and there will be many more; this short lesson is just the tip of the iceberg. In fact, the future of electricity could be a whole other blog in itself, but we’ll save that for another day. For now, we can give thanks to the series of inventions and discoveries made by a generation of great inventors. These influential people have laid the foundation for the electricity we probably take for granted today.