As you may have noticed, browsing our site (especially in the pages of the external units) you will surely have noticed the words: single-phase and three-phase power supply. These terms may seem complicated to you and that is why we decided to clarify this topic.

First of all, it must be specified that single-phase and three-phase concern the electrical circuits in which alternating current flows: both systems, in fact, have an oscillatory pace and what distinguishes them is the number of phases (among other things, the name suggests it).

What is a three-phase system?

A three-phase system is made up of 3 electric circuits where an alternating current flows consisting of 3 phases of equal voltage and frequency but phase shifted by 120°. Generally the voltage of these systems is 380 V, even if there are rare cases of old systems (including domestic ones) powered with a three-phase current at 220 V. This power supply is mainly used in industrial plants because for the same power the costs for the materials of generators and cables is about half. However, cutting costs is not the only reason: in fact, three-phase systems, in addition to being simpler to implement, are also more reliable and functional since they considerably reduce dispersions.

To have a reference scale, we can state that three-phase systems are used in the presence of powers above 6 kW. This value is decidedly higher than the canonical 3 KW present in the electrical systems of our homes.

But which of the two systems (single-phase or three-phase) is better? Neither is better than the other as each has its own quirks that make them more suitable for certain applications than others.