All courses › Electric Circuits › Phase and line voltage

Phase and line voltage

A three-phase system has three voltages shifted 120° from each other. The voltage between a phase and neutral is called phase voltage, and the voltage between two phases is called line voltage. In a star connection the line voltage is √3 times the phase voltage.

U_L = \sqrt{3}\,U_f

star connection

I_L = \sqrt{3}\,I_f

delta connection (currents)

Symbols

$U_L$	line voltage	V
$U_f$	phase voltage	V
$I_L$	line current	A
$I_f$	phase current	A

Example

A network with 230 V phase voltage:

$U_L = \sqrt3\cdot 230 \approx 400$ V.

400 V and 230 V are the same network, measured between different points.

Practise three-phase and power for free →

← Maximum Power Transfer · Three-phase power →

Part of Electric Circuits: Three-phase and power.