I work with equipment that operates on three phase electrical circuits. I can’t get my head around the concept of “phases.”
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Well, three phase electrical system is a neat trick to transfer more electrical energy via fewer wires.
Electric current needs at least two wires to propagate. Also there is a limit on how much energy you can transfer via wire of given length/gauge/material. Basically, if you try to squeeze too much energy in a cable it will begin to heat up, converting electricity into heat. In most severe cases it can burn out completely.
Three phase system uses clever trick to transfer electric energy via three wires. Neat thing is that you can transfer 3x more energy via 3 wires than via 2 wires. So, by adding one more wire, you are increasing energy throughput threefold. Those 3 wires are called “phases”. Each pair of those “phases” carries energy independently of others. So you have three pairs: A-B, A-C and B-C, thus three times more energy.
Pedantic reader will tell me that for three phase system you need 4 cables: 3 phases + neutral wire. But neutral wire is needed only in cases when there is imbalance between phases – energy is consumed inequally per phase . In ideal case you don’t need neutral wire at all or it can be very thin, as it carries almost no current. In energy distribution systems ground is often used as a neutral wire. But neutral is always present in last mile connection, because almost any end user will create imbalance between phases. Neutral wire will carry current caused by imbalance.
As an end user you need to know that voltage between two phases is much higher than between phase and neutral wire. So you need to be extra careful near 3 phase junctions/connectors/switches/etc.
As for how three phases work… Well, this is completely different question. It is hard to explain without drawing diagrams.
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