Apparent current

The apparent current is the alternating current taken from the power grid and flowing in a conductor . In the relevant standard, the term total current is used instead of apparent current . This current is made up of active and reactive current .

The effective value of the total current results from the effective values of the active current and the reactive current to ${\displaystyle I}$ ${\displaystyle I_{\mathrm {p} }}$ ${\displaystyle I_{\mathrm {q} }}$

Active current , reactive current and total current  in a parallel connection of inductive and ohmic loads with sinusoidal voltage  ${\displaystyle I_{\mathrm {p} }}$ ${\displaystyle I_{\mathrm {q} }}$ ${\displaystyle I}$ ${\displaystyle U}$

${\displaystyle I={\sqrt {I_{\mathrm {p} }^{2}+I_{\mathrm {q} }^{2}}}\ .}$

Phase shift angle

With a sinusoidal curve of current and voltage, an angle  between the phases of the active and total current of a consumer can be specified. The ratio of the active current  to the total current  corresponds to the ratio of the active power to the apparent power : ${\displaystyle \varphi }$ ${\displaystyle I_{\mathrm {p} }}$ ${\displaystyle I}$  ${\displaystyle P}$  ${\displaystyle S}$

${\displaystyle \cos \varphi ={\frac {I_{\mathrm {p} }}{I}}={\frac {P}{S}}\ .}$

In the case of an electric motor , the phase shift angle or its cosine is usually indicated on its nameplate .

Rated current

The maximum permissible effective value of the total current in continuous operation of a consumer is often referred to as the nominal current ; in a three-wire system , it applies to each individual outer conductor .

See also

• Impedance

supporting documents

1. ↑ DIN 40110-1: 1994-03 alternating current quantities