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You prompted me to look up how power stations are synchronised. This rabbit hole leads to The War of Currents. It's worth a read.

https://en.m.wikipedia.org/wiki/War_of_Currents



I've seen a few cases where there was a need to run 120VAC a thousand feet or so. The most cost effective solution being to step the voltage up to 240VAC and then back down at the load. Basically you save 75% on wires which pays for the two transformers. Bonus, you can use a tapped transformer to compensate for line loss.

120VAC -> 1.0T2.0 -> 240VAC --> line --> 220VAC --> 1.8T1.0 --> 120VAC


Where I am it's 240v to start with - presumably The Current War wasn't conclusive.

I understood it to make transmission easier but the US would face that problem at least as much as anywhere else...


American homes are typically 240vac, 60hz, between both hot lines. (That's what feeds car chargers, baseboard heaters, dryers, and stoves.) 120vac comes from taking one of the hot lines and one of the neutral lines. It allows a home to have two voltages without a transformer.


I have no information on the voltages used in the early AC grid but. In the US distribution is 15kV. So the turn down even for 240VAC is 60 to 1. Some experience with pre WWII house wiring says 20-50 amp service was common. The difference between the economics of AC vs DC might have not been so stark when people were running a couple of 60W lights.

[1]Seen three old houses run off two 20amp fused circuits.


The saddest casualty of war being Topsy :(.


Perhaps, but Topsy did kill a human first


In Topsy's defense, she was being held captive and forced to preform in a stressful environment.


Man must one day stop being inhumane to animals.


It‘s amazing how much opposition there apparently was against AC current – a technology that noone is afraid of today.


The open question for me is why did Edison even bother with DC at all? A DC generator requires a commutator. If there is anything that screams dodgy, that would be it.

Sliding friction. high current contacts. 60 times a second? Seriously?


Do incandescent bulbs last longer with DC, since they're not switching on and off 60 times a second?


There used to exist these "buttons" (for lack of a better term) that you could place at the bottom of a lamp socket to make your bulbs last longer. They were actually a diode shaped like a disc (more or less), that ultimately halved the amount of voltage going to the lamp (while also acting as a half-wave rectifier to form a noisy DC current). So in such an application - yeah, running a lamp at half its rated voltage would lengthen the life of the lamp (while reducing its brightness of course).

There was once the argument that DC would cause the lamp filament to vibrate like AC would (in the presence of the Earth's magnetic field?) - and thus if you ran your lamp on DC it would last longer due to not being mechanically stressed (I think this was one of the pitches behind those buttons, too).

I think it was later found that the argument had little validity, and was more a marketing pitch. That said, a lamp does experience a moment where, when the current (AC or DC) is switched on, the filament does "flex" - partially from magnetism, partially from thermal loading as it heats up. This flex, over time, does produce a mechanical stress on the filament. It's a major reason why incandescent lamps typically burn out when you turn them on.


Are they though? Bulbs take a brief period to turn off when hot and that cool down period is likely longer than 1/60th of a second.


Just like in politics, a lot of that opposition was manufactured by PR. Apparently Edison's company publicly executed an elephant using AC current to show the "dangers of AC".

https://en.wikipedia.org/wiki/Electrocuting_an_Elephant


Perhaps 100 years from now, it will be amazing how much opposition there was against human-caused global warming today – a connection that none may doubt then

I blame politics for both


Ironically I was reading recently(wish I could find the source) that some power distribution is switching back to DC due to the inductive load that the AC wave generates over long distances. Solid state has come along far enough that the conversion losses are comparable with AC transformers.


Undersea cable has been HVDC for a while, using [1]mercury arc rectifiers and inverters to do the conversion.

The interisland hvdc link in New Zealand[2] was still using some mercury arc equipment as late as 2012

[1] https://en.wikipedia.org/wiki/Mercury-arc_valve [2] https://en.wikipedia.org/wiki/HVDC_Inter-Island


This is because over long distances synchronizing power phases becomes a seriously problem, with serious consequences. By running HVDC you avoid the issue by pushing the phase synchronization to the endpoints.




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