Electromagnetic relay

Electromagnetic relays - the device for switching electrical circuits, where a magnet is the moving part, and a wire coil rests.

Terms and Definitions

Students Smithsonian's first electromagnetic relay is a device invented by Joseph Henry to demonstrate to students during lectures. Its essence resembled Telegraph: By pressing the signal went via wire mile-long, harbor collapsed by controlling the attraction of the electromagnet. As a result, the last held or lowered cargo weighing over 300 kg.

As for the Russian-language sources, merit of creating relay (without describing the operation principle) attributed Schilling. October 21, 1832 in St. Petersburg apartment he demonstrates brought to life the idea of ​​Ampère indicating alphabet by multipliers - measuring devices with DC swing frame. The telegraph was used electromagnetic platoon hour call mechanism, belongs to the category of inventions in the field of relays.

Strange interpretation arise where there is no pedantry, accuracy, correctness in terms. The authors have seen personally that the English-language domain for relay means any device key controlled electrical shock. What is fundamentally wrong. According to the definition Schilling and Joseph Henry described the invention may be classified as a relay, and in addition:

1. Orienting the magnetic field of the Earth frame Ampere (1820-1821 year) is a magneto-electric relays, indicating the presence in the current circuit for spatial orientation.
2. Wire Arago (1820), attracts metal filings is considered an indicator of the presence relay current in the circuit.
3. Arrow Oersted (1820), orientated in space in the magnetic field of direct conductor is an electromagnetic relay, the first of the demonstrated scientific community.
4. Shveyggera multiplier (1820) is a multiposition polarization electromagnetic relay, showing the presence of current in the circuit.
5. Observed in 1802, Giovanni Romanozi action conductor with current at the ferromagnetic material of the invented is the first electromagnetic relay.
6. Signals Indians neighboring tribe is quite possible to name the bonfire smoke-relay, the first known to mankind.

Easy to cause a lot of examples, for example, Sturge magnet lowers and raises the load on the distance from the source, first practical electrostatic telegraph in 1816, proving the golden rule: "Limits marasmus disputing parties do not exist".

From these examples easy to understand that the term of English dictionaries imprecise, vague. According to the interpretation in turn relays the doorbell, chandelier lighting, electric drill, an electric arc, and so on. It is clear that things do not match the essence of the subject.

Under Relay is a device created by man for their own use, broken and closes an electrical circuit under the control options of influencing factors.

Now, household items listed above does not fit the definition of a relay as new items 1831 and 1832 by Henry and Schilling described above. We call them by telegraph, an electromagnet, a cartoonist, an alarm clock, a beautiful piano, but never will they inherently relay. In addition, in this case, the prerogative of the implementation of the magnetoelectric relay uniquely belongs Ampere, who was able to orient the frame in the magnetic field of the Earth, feeding into the loop current. And Oersted did something similar... It is noteworthy that some types of sensors according to this definition can be attributed to the relay, for example, the transistor switches. Again, this is true because of solid-state electronics future.

Thus, eliminating the uncertainty of the determination of one (tautology should not go unnoticed), should be supplemented and certain other terms. Now we are talking about epithets, because not everyone can explain why it's suddenly "switch" Ampere called magneto, and Henry - electromagnetic. According to the author's humble opinion - although it is nowhere expressly stated - the situation is as follows:

1. In the electromagnetic relay armature (the movable part of the installation) is a ferromagnetic alloy. Henry is suspended playground, crowded with weights.
2. The magnetoelectric relay anchor is a coil. It is clear that the amp has not managed to turn the molten metallic core of the Earth.

The first magnetoelectric relay

To illustrate, the world's first switch is convenient to use the experimental setup Sawyer Bert (Bert Sawyer), shown in the screenshot (Youtube channel: youtube.com/channel/UC-RNJLpsykDpbZDeotK3xw). This little-known in Russia koromyselny engine Joseph Henry, dated July 1831 (American Journal of Science 20: 342). The device is a dual magnetoelectric retractive relay. The essence of the design:

1. The engine is mounted on a frame of solid wood in the form of a rectangle.
2. cylinders standing on the sides mimic popular in the days of Henry galvanic cells of the zinc and copper circles. Of course, Bert Sawyer there are converters AC voltage power frequency AC power into DC power.
3. On top of the flat pads batteries are bowl-caps. On the first screenshot empty, the installation is not yet ready for use. Later, here it is filled with water from the tap, which is a good conductor. In the 30s of the XIX century and used mercury in devices of Michael Faraday.
4. The edges of the battery in the middle connects the steel beam resting on two supports. This is a fixed part of the relay.
5. Follower onto axle through two A-shaped supports, located exactly in the middle.
6. For each rocker arm wound electromagnet of lacquered copper wire feeding contacts located on the opposite side.
7. Along the edge of the frame (support) is an electrical switch in the form of long cutting brass rod, rotating around an axis located at the end.

After preparing vials and closures rocker key starts alternately inclined to the sides (see. second screen) around the axis. The frequency of oscillation is low and around 2 Hz. What is happening is enough to say that there is the world's first magnetoelectric relay (stationary magnet). Contacts alternately make and break their own supply chain winding both shoulders.

The merit Henry - scientist demonstrated the possibility of interrupting electric current flow path. First of mercury (and possibly water) is often used. This is done by Michael Faraday in the autumn of 1821, creating the first electric motor. His experience (after the report, heard September 11, 1821) repeated in December Amps. What is reported (Academy) January 7, 1822. Called, and other examples of the use of liquid contact, the beginning of the use of which put Sir Humphrey Davy in the early 1800s, opening the electrolysis. The first who discovered the conductivity, consider the great Alessandro Volta, to repeat the experience of Luigi Galvani.

So, the idea of ​​an automatic opening and closing contacts (without human intervention) owned by Joseph Henry. Now it is easy to prove that this was the first relay. Thoughts create a new engine and the telegraph inventor hovered in my head since 1827. Henry in the annual report for the year 1857 the Smithsonian Institution shows that he knows about the three kinds of telegraph (see. screen):

1. Electrostatic (proposed in the middle of the XVIII century - see. Impulse relays).
2. Galvanic, a hand and Henry.
3. Electromagnetic - where an alarm signal in the receiver is in the form of a rotating arrow or ring signal.

In the aforesaid paper by Henry shows that (up to November 1832) has developed a method of controlling weak high power signals at a considerable distance: the electromagnet is powered via a relay from the local source. According to the scientist, this work, in contrast to previous research has not been published in the journal Silliman`s Journal or other media. It turns out, Joseph Henry invented the concept of the electromagnetic (and magneto) relays. The scientist realized ideas and practice on the basis of the school laboratory, while recognizing their own experiences little known to the public and poorly documented, Joseph Henry says:

1. Before me are known electrically magnets, no one tried to manage them from a distance.
2. I first was able to manage a large force of the magnet from a distance. It took significantly change the structure of existing products at the time. For example, applied parallel connection of a plurality of coils to increase the current.
3. The first managed to magnetize a piece of mild steel at a distance, and drew attention to the fact that the transmission of such impact on the long distance is allowed to be used in telegraphy.
4. The first forced to ring the bell from a far distance.
5. My unpublished developments helped Mr. Gale to adapt Morse telegraph to work over long distances.

It verbatim from the case against Morse O`Rayli shown in the screenshot: at the beginning of April 1837, Joseph Henry was in Europe, where he met with Professor Wheatstone and Professor Bachem (Bache). Pundits discussed the idea of ​​the telegraph, where it appeared that they had established two ideas of realization of the same relay concept in the field of communication over long distances:

1. Wheatstone explained that he wanted to make the rotary switch for the remote control circuit, opens and closes the contacts of the local power supply. That will dramatically reduce the requirements to the transmitter. The newly constructed relay belongs to a class of electromagnetic and took the principle of action of the multiplier.
2. Then Henry said that for many years considering different design, similar in action. In his vision of the contacts must open and close steadily moving armature. This principle is now used by the overwhelming majority of electric breaker.

Thus, the people mentioned above are considered the most likely inventors of the electromagnetic relay. Magnetoelectric exactly manufactured by Professor Henry, as mentioned hereinabove. With regard to national, unfortunately, his opinion remains unknown due to the lack of historical documents on the official Russian site.