Connect 120 volt circuits to get 240 volts

240 volts at a home or business that doesn't have 240 volt outlets is to p ick off two outlets that are wired to separate circuits on opposite sides o f the 240 volt power. There is a commercial product for this and designs o n the web. I found this schematic.

ems the issue is that without the input relays when you plug the unit into one outlet the path through the output relay coil can energize an exposed p lug pin. But I don't see the need for two poles. Running the 120 volt con nection through the input relay contacts on just one side of the output rel ay coil will prevent the two inputs from being energized when only one is p lugged in.

only advantage I can see is that with the two pole relays a single stuck co ntact won't be dangerous. In a one pole approach it can pass a dangerous v oltage to the input plug pin. But you can hear relays working so a stuck r elay can be detected. Also it has indicators on the inputs so you can tell the relay isn't clicking because of a failure rather than simply no voltag e. So this risk seems minimal.

won't pull in and connect the load. I'm pretty sure 120 won't do it and I 'm sure 0 volts won't of either polarity.

Relays frequently work fine on 50% voltage.

NT

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number of EVs.

It isn't, unless one unrealistically restricts them to charging overnight o nly on low power.

on trips away from home and the small proportion of EVs that don't have ho me charging. In general fast DC and other day time charging will be a smal l proportion of the total EV charge load. Most of it will be done from hom e since that is most convenient and cheapest.

commercial vehicles frequently run all day day after day. You can't do that with an overnight charge from a 13A socket. The infrastructure can support some easily enough, but not widespread deployment.

lans will be in place to do two things. First there will be time control o ver charging controlled by the grid. Second, to promote participation in t his charging time control the reduced cost of generating this power will be shared with the EV owners.

Probably, but that won't be enough

NT

A PC fan? :)

NT

240 volts at a home or business that doesn't have 240 volt outlets is to pi ck off two outlets that are wired to separate circuits on opposite sides of the 240 volt power. There is a commercial product for this and designs on the web. I found this schematic.

K3 is unlikely to drop out if its coil only sees 50% of the voltage. The ci rcuit works on non-RCDed feeds. But if one circuit is RCDed, most likely bo th will be, and it won't work at all.

NT

e main via 4 #6 or #8 wires. 440V should be optional. I want 440V in my g arage.

he US. Hope it gets to residential users eventually. 240V is not enough f or EV, or aluminum melter. I want to charge up my EV and melt and cast alu minum.

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yeh, my apartment with installations "upgraded" some time in early 70's has 3*10A + 10A fuses

afaict the standard installation for a house is 3*35A and you can get more for ~$2000 per ~15A

Due to the large fuses feeding the sockets, you need to have smaller fuses installed in each mains _plug_, so the distribution panel can be very small, when the fuse selectivity is distributed into all plugs.

It seems to me the electric utility industry is slow to respond to the probable EV charging demands.

Not only is there a power generation problem there is a last mile problem also.

And, they already have an idea I was going to mention.

in which it acts as a giant battery and injects the power back into the grid."

Mikek

At least EVs do not require block heaters (about 1 kW), so that power could be used to charge batteries. For a night perhaps 10 kWh. If one believes the EV manufacturer claims, you can drive several kilometers with one kWh. It depends of course on the environment, but what is the average daily commuting distance in your area ?

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The energy needs for various utility vehicles is of course much larger, but still city buses can run with a high power charging station at only at one end of the line. The battery is fully charged in the time the driver visits the restroom or smokes a cigarette.

After upgraded water and electricity this decade. I now have 3-phase also in my city apartment, the stove is connected via 3 x 16 A fuses.

In my country house, I have electric stove on 3 x 16 A and also electric sauna on 3 x 16 A. IIRC, the main fuses have been 3 x 35 A for decades.

few years ago, you couldn't even get a single phase connection, but now it is apparently possible to get 1 x 10 A for a small summer cottage at least in some districts.

We have 50GW if everything is operational - which it never is.

Last I heard we expected to have about 4% spare capacity at some times of the year, which is too low for comfort. It wouldn't take many "events, dear boy, events" for there to be "immediate opportunities".

I went to a professional talk on this topic at a local university maybe 18 months ago. At the beginning they posed the question "what chance is there that the lights would go out?". At the end all those in the industry said

100%. The only questions are when, and under what circumstances - which does leave a little wriggle room.

That just sounds like the N-1 criterion (4 % of 50 GW is 2000 MW) . This means that you can survive the trip of the largest (nuclear) power plant. After such trip event additional power plants are started and it can take 30 min to a few hours until the N-1 status is restored so that the next largest plant can drop out. If there is an other trip during the 30+ minute restoration period, you have to shread loads, if you do not want to loose the whole network.

IIRC the margin was down from 5/6% which was regarded as much more comfortable. But basically the "one reserve plant" accords with my limited understanding.

Unfortunately multiple unplanned outages do occur.

This month: EDF Energy has extended by several weeks outages at its Hunterston nuclear plant in Britain, while the company seeks to prove it is safe for the more than 40-year-old plant to restart after cracks were discovered this year.

2015: Energy giant EDF Energy saw its UK profits

following unplanned outages at two of its nuclear power stations, it reported today.

... etc.

Not comforting, albeit it accords with the "we got through the Blitz" mentality associated with the Maoist Brexiteers.

How?

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

The UK grid has never actually blacked out - which is a miracle.

If it did, restarting would be fun given how tricky a blackstart is. I think at that point, the government might realise the error of their ways over the last couple of decades.

The old CEGB (Central Electricity Generating Board) that ran the Grid and all the power stations was one of the very few nationalised industries that worked - and not only, it worked exceptionally well.

That was one thing that should not have been privatised.

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Email does not work

Because I thought he wanted to charge a cell phone. Ooops.

If you're going to use several different circuits in some kind of building, you're really going to have to have a good knowledge of the wiring of that building and know what is on each circuit so you don't overload any of the branch circuits.

I would just go to the main breaker panel and wire in the proper 240 VAC circuit instead of trying to use a whole bunch of extention cords and relays and plugs and stuff.

This is our breaker box:

The main service is 120-0-120 at 125+125 amps. Most outlets are 120V, but a few are 240.

We don't have air conditioning, and heating/hot water/stovetop/clothes dryer are natural gas, so our power feed is fairly small. I don't think we have tripped a breaker since we moved in in 1993.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

One of the principal reasons for the small pumped hydro schemes at Cruachan and Trawsfynned is for blackstart.

One of many :(

The idiot accountants in Thatcher's government noted that the major plant and network was nearing the end of its depreciation period, and thus "had" to be "replaced". The government didn't want to fund that, so they sold off that bit of the family silver to the private sector.

The private sector noted that "depreciation life" != operational life, and bought it for far too little.

Since then the private sector has been doing its usual good job of "enhancing shareholder value" by running things beyond their natural life and not enhancing them.

When, not if, the shit hits the fan, the proles will be expected to bail out the fat cats yet /again/. The risks and rewards are asymmetric, as shown by the privatised NHS contracts "oops we bid too low and can't make a profit; bye bye", ditto railway franchises, ditto banks.

There is also the "stinger" connection, which is 3-phase 240 line-to-line, with the center tap of one leg making 120-N-120.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics

GFDs are not very common here in the US, only required in outlets near sinks and tubs and sometimes near concrete garage floors. Usually not in breaker panels. 120 is not as dangerous as 240.

But that horrible circuit is horrible. There are sneak states, and the author (I hesitate to say "designer") seems to assume that a 240V AC relay pulls in and drops out at close to 240 volts.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics