Comments by "Jovet" (@jovetj) on "How Three Phase Electricity works - The basics explained" video.

  1. Remember all materials resist the flow of electricity. That resistance mostly manifests as heat, which is the answer to your question.
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  2. AnantaSesaDas - This video is an adequate but very basic explanation about why three-phase power exists and how the phases work. Most homes and some businesses are only supplied with one phase. It doesn't matter which phase is used, but as Joe Meso points out, the power company will want to keep the loads on the phases as balanced as is practical. The distribution of three phase power is more complicated than shown in the video. Usually, the phases are interconnected in some way, creating what's called a "delta" or a "wye" circuit. "Delta" circuits require four wires, and are the most common power line configuration you'll see that are not transmission lines. In these circuits, the voltage potential across the three phases and to the fourth neutral wire is usually not equal. 240/208/240 volt three-phase service is common. Higher voltages are also around, but note that one of the voltages is not the same. Here it matters knowing which phase has a different voltage, so "random" won't work. In the U.S., the wires coming into your home are not phases like this. Instead, one high voltage phase is fed into a transformer which steps down the voltage to 240 volts. But the transformer's output has what's called a "center tap" which means a third wire is connected to the middle of the output winding of the transformer. This means that the original, full winding of the transformer is still 240 volts, but the voltage across the middle wire to either of the other two is 120 volts. This requires three wires into your home. Your grandpa's house does not have 240 volt service at all. In a building with three phase service like described above, there may be secondary transformers in the building to convert the three-phase power to regular 240/120 volt service for lights and regular electrical equipment.
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  3. A phase is not the same thing as a circuit in a building.
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  4. Because that would be much less efficient. Two phases is just not sufficient. Three is the minimum required to justify the expense of the fancier generator and extra wires.
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  5. A simplified explanation is that the electrons move at the same speed no matter the voltage, they just don't move as far.
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  6. @Joe Vignolo I think we were talking about differences in voltage, not amperage.
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  7. P = I × V
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  8. The video only covered theoretical ideals on why three-phase power exists and how it's used. Practical circuits are said to follow in a later video. Yes, motors are the most-common use for 3-phase circuits because they make a motor so much more efficient, smaller, and simpler to construct. Other uses include heaters and lights. The distribution of 3-phase in a device depends on its design.
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  9. Yes. Without Mr. Tesla today's power grid would be 100 years behind. Mr. Tesla was the one who "invented" AC power, transformers, etc...
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  10. The video did not touch on 3-phase transformers or how three-phase circuits work in a practical manner.
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  11. Just hink of redundant coils.
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