Who Invented Three-Phase?

Seems to be some confusion, I have Oskar Von Miller

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Nikola Tesla

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and

Galileo Ferraris

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and

John Hopkinson

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Hardy

Reply to
HardySpicer
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Close but no cigar. Tesla beat him by at least a year, probably more.

Most likely the winner. Certainly invented the rotating field concept which is essential to his invention of the induction motor.

This guy is probably a "parallel" inventor. Time frame is about the same as Tesla though his patent was issued about the time of the Ferraris paper which could give Tesla a slight edge (takes time from idea to patent), but without an exact time-frame for each man, it's hard to say for sure. But Tesla does have the patent and that was never challenged.

Nope. Only invented three phase power transmission. Though had priority for that (1882 patent) He did not invent induction motors or the rotating field.

Although for any important invention, there are always lots of "after the fact" persons discovered later for whom it is often claimed the invention (or their "friends" claim it for them). This is very common.

A guy I used to work with had this "seeds" theory about it. His "theory" was that when it was time for a new invention in the world, the "powers that be" would sort of drop "seeds" for the new idea from heaven. They would fall all over the earth. Some inventors would pick them up and run with them. Some would sort of give them a look and nothing more and others would ignore them or not notice them at all. Yes, it's kind of a "joke" theory, but on the other hand it does fit the data of the way great inventions commonly happen. It is VERY common for 'great" inventions to appear simultaneously in several places around the world at the same time!

And then one must add to the the politically motivated erasure of Tesla's achievements from technical history. Started by J.P. Morgan who basically "milked" Tesla for anything profitable ("Nobody milks my cow for free!") and continued pretty much to this day because of certain interests of Tesla that the power-elite would just as soon the general public not consider as real science. Even now, if one mentions Tesla there are the "debunkers" on the internet who descend to call him "insane". The fact that this "nutjob" held about 300 patents that cover most of the major devices that defined the 20th century from the fluorescent lamp to the car speedometer is swept under the rug.

Reply to
Benj

I only wanted the invention of 3 phase, not the rotating magnetic field or the induction motor. Maybe Hopkinson then.

Reply to
HardySpicer

Lots of people worked on polyphase power systems, but it was Tesla that patented three phase.

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Jim Pennino

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Reply to
jimp

Edison was a hack that stole much more than he ever invented. Tesla was just another brilliant guy in Edison's employ that did all the work, came up with all the innovations, and Edison took all the credit and money. A true poster boy for Wall Street, but no great inventor.

Reply to
WangoTango

I don't know the timing of things, but one of the earliest AC electrical systems was 90 degree 2 phase power. By this I mean two wires to the load carried AC at 0 degrees and two others (separate circuit) carried AC at 90 degrees to the first pair. This produced a rotating field in a 2 phase motor and constant power (since sin**2(x) + cos**2(x) = 1). You needed 4 wires.

You could connect two of the wires (one from each phase), call it a neutral and get away with three wires, but the neutral carries quite a bit of current. Three phase is better at carrying more power with the same copper in three wires, which is why you don't see two phase power any more, except in some specialty motor control circuits.

There was another early power system that was a cross between two phase and the single phase Edison system still used in the US. Take the existing Edison system and add a supply at 90 degrees, connected to the neutral center tap. Lights were connected as usual to the Edison system and motors as well, but the extra phase was connected to a starting winding on the motors. One thing that was interesting about this was, as long as you had at least one motor running, it would generate the extra phase and could start other motors even if the extra phase was not being supplied by the utility. Some people use a similar trick to run small 3 phase motors off the US domestic single phase supply, by running a (manually started) idler motor that generates three phases for other motors connected to it.

Reply to
Michael Moroney

Usually the idler motor is capacitor start. Why manually start it when you can get start caps surplus? Search on "rotary phase converter".

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Tim Wescott
Wescott Design Services
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Reply to
Tim Wescott

Some of these things just grow out of the spirit of the times, getting invented multiple times by multiple people in multiple places.

Three-phase power is certainly one of those technologies that would easily have more than one daddy.

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Tim Wescott
Wescott Design Services
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Reply to
Tim Wescott

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Isn't the 'purpose' of three phase to run induction motors?

George H.

Reply to
George Herold

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No, it's a method of distribution that is more efficient than single phase for the same amount of copper. Three phase supplies our homes - except we use only one of the phases of course. Small induction motor can run on single phase with a capacitor start to simulate a second phase.

Hardy

Reply to
HardySpicer

It certainly makes sense to start the idler capacitively. The setup I saw was relatively simple compared to some of the setups that turn up when searching for "rotary phase converter".

Reply to
Michael Moroney

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OK, I always associate three phase with running induction motors, lathes and mills in a machine shop for instance. I don't know about power transmission.

George H.

Reply to
George Herold

Well, that plus for DC rectification, it takes significantly less filtering than single-phase.

Cheers! Rich

Reply to
Rich Grise

Many AM transmitters, where high DC voltage is required for the power output tubes, use transformers to convert the three phase supply to six phase before rectifying it. This reduces the filtering required still more.

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Virg Wall, P.E.
Reply to
VWWall

Definitely.

In some European countries, the maximum allowed single phase motors are about 1 kW.

The smallest induction motor that I have at home in the central heating system circulation water pump with perhaps 100 W power (my guess based on the motor size) protected by 3 x 2 A fuses.

Starting capacitors are used with single phase low power units.

Universal AC/DC motors are used with hand tools etc.

Reply to
upsidedown

More to start them than to run them.

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Many thanks,

Don Lancaster                          voice phone: (928)428-4073
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Reply to
Don Lancaster

one: (928)428-4073

Well don't think that the whole world of power revolves around the induction motor. It is more efficient to use 3 phase.

Reply to
HardySpicer

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