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Joined: Jul 2004
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Edison, who was more of a marketeer than a scientist saw DC as a system that would involve lots of generators spread across the city, all sold by him. Tesla and Westinghouse envisioned the grid and a few very large generation facilities providing power to a wide area of customers, using transformers they sold. Tesla even dabbled with the idea of transmitting power over the air.
They were both advancing their plans at roughly the same time though. (1880s)
I don't think there were any large scale DC distribution networks but Edison did sell a lot of generators for individual mansions, offices and factories.
By the time large scale distribution systems came online, AC had won the fight.


Greg Fretwell
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Edison was also a rather shameless self-promoter.
He offered a HUGE discount on generation equipment to any company that would put "Edison" in their name.

Consolidated Edison...Commonwealth Edison...Ohio Edison...etc.


Ghost307
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Edison's biggest invention was the "intellectual property agreement". Most of the stuff he is credited with inventing was actually developed by the large staff of young engineers he employed. He had people working on every thing he ever dreamed up. Most went nowhere but occasionally something worked out. Then he had the marketing skill to bring it to market. It is really not unlike companies like Microsoft and Apple.


Greg Fretwell
Joined: Dec 2001
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From what I've read 3-wire DC was already an attempt to cut voltage drop-related losses in local-scale DC distribution networks spanning roughly the size of a neighbourhood. The first DC systems were plain 2-wire. In the Budapest Electrotechnical Museum you can see the very first working transformer, which is a symmetrical three-phase transformer so I'm fairly sure 1-phase 3-wire AC came later but the question is how much later.

120 V AC never made an awful lot of sense TBH. The voltage is too high to be considered safe (the limit is 50 V AC or 65 at the highest) but too low to drive substantial loads without requiring fairly high currents and large conductors. Higher currents also cause higher voltage drops. Just to give you an example: a cooker (range) with three sets of elements each connected to one phase and neutral of a 230/400 V system could be connected using 14-4 NM cable using a 3-pole 15 amp MCB. The same load connected to 230 V requires a 50 amp MCB if full functionality is required (although most European countries factor in load diversity as it's unlikely that all elements will draw full current at the same time as the elements are thermostat-controlled) and allow for 25 or 32 amps to be used).

Mains voltage is always a compromise between insulation and low currents. Frequency is mainly a compromise between equipment size (transformer cores, motors and generators) and motor/generator RPMs, the higher the frequency the more poles a slow-running motor or generator needs to have. I think we'll likely be stuck with 50 and 60 Hz forever since changing a large grid's frequency seems pretty much impossible unless the grid is split up into smaller sections temporarily DC-coupled and since more and more equipment accepts more than one frequency I can hardly see such a conversion being feasible either. Voltages on the other hand may change, as South Korea has shown. As far as I know the country changed over from 120/240 V 3w to 230/400 V 4w in a period of only two or three decades (1970s to 90s).

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dsk Offline
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Regardless of frequency, 110 vas the maximum practical voltage for the Edison lamp with a carbon filament.
That is the only practical reason I see for 110V

The North American 60hz 480V system motors are actually compatible with European 50Hz 400V motors and vice versa.

dsk

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Originally Posted by dsk


The North American 60hz 480V system motors are actually compatible with European 50Hz 400V motors and vice versa.

dsk

I don't see how that is even workable.


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I think a 60hz motor would still run at 50hz but if it is an induction motor it will run hotter and slower.


Greg Fretwell
Joined: Mar 2015
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Back in the dim and distant i went to the US on holiday my brother took his electric razor with him it had a switch to select either 110 or 220 volts working but nothing to say it would be suitable for 60 cycles mains he used it and it ran a bit faster he said he got a better shave than back at home I did consider building a small 50 to 60 cycle converter but in the end thought it was more trouble than it was worth

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With the availability of cheap switcher power supplies that have a wide mouth, using things internationally with no changes at all is becoming common. When we went to New Zealand, all of our electronics made the move seamlessly. I just needed a power plug adapter that changed the NZ plug to a NEMA 5-15 We plugged a cube tap into that and everything we had plugged right in.


Greg Fretwell
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dsk Offline
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Originally Posted by gfretwell
I think a 60hz motor would still run at 50hz but if it is an induction motor it will run hotter and slower.

That is correct, the 50Hz motors does hoften have more iron (are heavier) so temperature monitoring may be a good idea.
The speed of an induction motor will follow the frequency!

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