I don’t necessarily understand how it can be termed 3 ph power,because we don’t simply get 3ph to homes as we please,right? Moreover we don’t have any heavy machinery that might even require it. Could someone explain how this arrangement works? Is it just switching between feeders like in a ring fed arrangement of the power system? Or is it actually 3ph power(?)
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If you’re choosing between 3 lines. Those lines would be your three phases. It seems strange that you would have to choose, as the lines all travel on the same poles. So if one line goes down, arguably so would the others.
I’m not sure what country you live in. Where I live it’s 3 phase on the pole and single phase to the houses.
I’m sorry not really a good explanation. I’m an electrician but I haven’t seen anything like that where I live.
Generators make electricity when they rotate a magnet next to a coil. It generates electricity in one direction as the magnet passes by the coil one way, and in the other direction as it passes by the other way. But it generates nothing when the magnet’s head is away from the coil, and as generating electricity creates a force slowing down the spinning magnet, the force increases and decreases as the magnet spins.
With the forces involved in large generators, This uneven load would create vibrations that would destroy them.
If you put 3 generators – 3 sets of coils around the same magnet – this evens out the load. When one coil isn’t generating power, the other two are, and when one is at its maximum, the other two are generating less. The 3 independent coils create 3 independent supplies of electricity, each having voltages that peak at different times. These are the 3 phases of an electricity supply. You can pull power from them by connecting your device between a phase and neutral, or connecting it between different phases.
But you are right – 3-phase supply is unusual in residential areas. You normally have to pay extra, and people only do this if they have large equipment, especially large motors, that run more smoothly when using a 3-phase supply, for the same reason that generators do. Your sparky decided that, as you already had a 3-phase supply – perhaps the previous owner had a large device that used it – he’d give you the option of switching your supply between the phases. Sometimes one (or, more commonly, 2) phases stop working, and at those times it would be nice to switch your house to the working phase. But your power company might not like this – they spend some time arranging things to balance the load on the phases.
Power plants generate 3phase power as it is more efficient to generate and transport. It uses a different wire for each phase.
3phase power is running down the street and generally also into houses. 3phase power allows you to connect heavy loads. and a normal houshold only needs a single phase.
The electricity company will hook you up to one of these phases ensuring all 3 phases in the neighbourhood are loaded more or less equaly. (Your neighbour is probably connected to a different phase than you.)
If phases are loaded unequally, a certain phase might become overloaded and the voltage might sag on that phase. The selector switch allows you to easily switch to another phase.
In rare occasions, a single phase might be interupted due to damage. Also in this case you can switch to a different, still working phase.
In cases of feed-in (solar panels) the selector switch allows for injecting electricity into the phase that is in the most need for power.
It is uncommon that this is done manually and in a normal household.
You’re not quite selecting between the three lines.
The electricity that comes from the power plant is three phase (read u/robbak’s explanation how it’s made) and carried by three wires. Each phase is a a pair of those wires. If we call the wires A, B, and C, the three phases are AB, AC, and BC. For most residential power, one of those pairs gets picked and you only have a single phase.
The best way to imagine what’s happening in the switch is that the three phase wires are coming in as the points of a triangle and the switch is choosing which single side of that triangle is supplying your house. You can’t have all three phases feed into a single phase system since that would be a three phase short and blow up the switch (and the closest transformer if you’re unlucky).
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