EL
BG
DE
ES
FR
ITGlossary · Electrical units
Single-phase Power
An electrical system with one alternating current (AC) voltage phase, commonly used in homes and offices.
Technical level:Basic
In single-phase power, electricity arrives through one phase conductor and one neutral, together with the earth conductor. In Greece and the rest of Europe the nominal voltage is 230 V at 50 Hz, and it supplies most homes, offices and small shops.
When choosing a UPS, a single-phase supply determines the type of unit: single-phase UPS units (single-phase input and output) typically cover power up to roughly 10–20 kVA, which is enough for computers, small servers, boilers or security systems. Above that level a three-phase solution is preferred.
Before installation, check that the circuit breaker and cable cross-section of the line can handle the UPS input current, especially while the batteries are charging.
Questions that mention it
All frequently asked questionsWhat do single-phase and three-phase power mean?
Single-phase power (230V) is traditionally used in homes and covers the basic needs of a residential installation. Three-phase power (400V), on the other hand, offers more power and stability for high energy demands, such as heat pumps, EV chargers and so on.
Related terms
- Noise (Electrical)Unwanted high-frequency disturbances on the supply voltage, e.g. from motors or power supplies, which UPS systems and line conditioners filter out.
- Three-phase PowerA supply with three AC phases shifted by 120° (400 V between phases), used for large loads, motors and UPS systems from about 10 kVA.
- Hardwired (Terminal Block) ConnectionPermanent connection of the UPS input or output by an electrician, with cables screwed into a terminal block instead of plugs and sockets, usually on higher-power UPS units.
- IEC C19/C20 ConnectorsPair of connectors rated up to 16 A under IEC 60320, used on higher-power UPS units, rack PDUs and servers or switches with high-consumption power supplies.
- Inrush CurrentThe initial surge of current required when electrical equipment is first powered on.
- kVA (kilovolt-ampere)A unit of apparent power equal to 1,000 VA, used to rate UPS systems; real power in kW equals kVA × power factor.