Early History of The Electric Motor
When Michael Faraday in Great Britain and Joseph Henry in the United States both discovered electricity, at roughly the same time, nobody knew what to do with it because in those days nothing in the world worked on electricity.
In fact the world was a fairly sombre place until we learned to create electricity and to harness its power. Within 150 years it had completely changed our existence, from the way we live and work to the way we arrange our affairs. However in the early 1800’s electricity was still extremely experimental and the electric motor and electric generator, as we know them, had not been invented.
Up until the 1830’s there were only two ways of producing high voltages. One approach involved frictional electric machines that used a glass cylinder or plates carrying conductive segments that rotated and rubbed against pads of various materials. (Wimshurst machine).
Leyden Jars (early capacitors) were often used with these frictional electrical machines to store the electrical charges produced.
The other method was to use early batteries which at that time consisted of a varying number of Voltaic Piles connected in series. Many cells had to be used to produce higher voltages and they were very expensive.
INVENTION OF THE ELECTRO-MAGNET
The first step towards the invention of the electromagnet that led to the invention of the generator and the transformer was taken by Hans C Oersted, a Danish Professor, who discovered that a current carrying conductor would cause a magnetic needle in its vicinity to orient itself at right angles to the conductor. This was quickly confirmed by many other scientists.
In the 1820’s and early 1830’s two of the leading experimenters of the day, Michael Faraday and Joseph Henry constructed apparatus, based on this discovery, that are often described as the first electric motors and Faraday went on to discover electromagnetic induction and magneto-electric induction in 1831 and Henry to discover self-induction.
Electromagnetic induction is the generation of electricity in a wire by means of the electromagnetic effect of a current in another wire. This was the first electric transformer.
Magneto-electric induction is the process in which the magnetic field of a moving permanent magnet produces a steady current in a wire or coil located nearby without touching it. This was the first electric generator. Following Faraday’s magneto-electric discovery the Frenchman Hippolyte Pixii developed a rotary motion generator based on Faraday’s principles and power is still generated today using these principles.
Inductively generated electricity was first adopted by medicine for use in electrotherapeutics as magneto-electric machines were more reliable and convenient to use than the voltaic pile or electrostatic machines.
During the early part of the 1830’s the subsequent development of engines that could be powered by this newly discovered “electricity” was an international affair. In Italy, Salvatore dal Negro built an electric motor that produced a reciprocating motion. Another linear motor was built in France by Paul Fromont. In the United States, Joseph Henry built an experimental motor as did Charles Grafton Page and Thomas Davenport. In Russia, H M Jacobi powered a paddle boat with a rotary electric motor and Scotland’s Robert Davidson used eight electromagnets to propel a carriage. Many of these early motors used additional mechanical devices to achieve rotary motion.
STEAM STILL KING
At this stage of the industrial revolution “Steam was King” and it would take nearly thirty years before electric motors would be developed that we would recognize today. The problem was that there was little use for a constant source of electricity and therefore there was no incentive to create electric generators. It was not until the Carbon Arc Lamp, invented by Humphrey Davy in 1808, was coupled to an early dynamo in 1858 to power these lamps in lighthouses that demand was created. With this demand for constant power came an improvement in supply which in turn hastened the development of electric motors.
One of the first public demonstrations of an electric motor occurred at the Vienna Exhibition of 1873, when a generator invented by Zenobe Gramme was used as a motor to operate a pump; its power was supplied by an identical generator. This demonstrated the “not always obvious” fact that an electric motor works just like an electric generator, except that a generators output is a motors input.
Movement in a generator produces electric current, whereas electric current causes a motor to move.
During the 30 years between 1830 and 1860 many attempts were made to use electromagnetism to produce engines that could be used instead of steam and one group of experimenters converted the linear motions of their inventions to rotary motion via linkages similar to those found in steam engines of the time. The early engines of Charles Grafton Page took this form.
CHARLES GRAFTON PAGE
Dr Page was perhaps one of the most prolific inventors of his time and developed many electro-magnetic engines both reciprocating and rotary as well as other early electrical apparatus many of which were built and sold by Daniel Davis of Boston, the leading manufacturer of electro-magnetic machines of the time.
Steam engines of the time produced a reciprocating motion in which large masses oscillate back and forth in harmonic motion. From an engineering standpoint, this makes little sense, as the reciprocating parts must continually be accelerated. Most applications require the reciprocating motion to be converted to rotational motion using the cross-head mechanism invented by James Watt in 1750.
The first electric motors consisted of machines with reciprocating motion and although this first group came to a dead end, fascinating and beautifully made examples survive in various museums around the world.
A second group of rotating designs quickly appeared and these designs evolved into the modern electric motor.
It should be recognized that reciprocating steam engines are no more and have been replaced with rotary steam turbines that produce electricity to this day.
Early rotating motors are often referred to as Froment motors after the Frenchman Paul-Gustav Froment, who in 1844 devised a motor where electromagnets are energized to pull iron bars mounted on a wheel. When the bar was level with the magnet the power was cut off until the next bar approached. In this way he achieved constant rotation.
Other experimenters such as Page, Ritchie, Jacobi, Davenport and Davidson also made early rotary motors.
It is now recognized that the English scientist William Sturgeon invented an electromagnet and rotary motor as well as other electrical apparatus as early as 1832 but his work was not internationally known at that time.
EDWARDIAN ELECTRIC ENGINES
By the end of the 1800’s numerous designs of electric motors had been developed in the search for better efficiency.
The concept of wound armatures working with un-wound stators was beginning to gain attention such as the early motors of Charles Wheatstone where the wound armature rotated within an iron ring (the stator).
Other groups continued with the wound stator but placed the armatures within a revolving flywheel which made it more like a rotor.
One such group were Harry Hawekotte and Henry Klausmann, both from Indianapolis, Indiana. In about 1908 these engineers produced a number of demonstration engines where the armatures passed between the rods of the wound stator instead of close to the rod ends. This was more efficient and the rotor incorporating the armatures was becoming a dedicated component.
The models of historic electromagnetic engines manufactured by the Old Model Company Ltd are examples of early reciprocating engines and of rotary engines first produced between 1830 and the early 1900’s.