Rated current

The nominal current is the current flowing in an electrical device when the device is supplied with the nominal voltage and delivers its nominal power .

Explanation

For example, taking a 60 W incandescent lamp at 230 V (nominal) (theoretically) a nominal current of 0.26  A to. However, their inrush current is much higher because the resistance of the filament is temperature dependent. The current intensity actually consumed is also dependent on the electrical voltage , with an ideal ohmic resistance in proportion to this voltage.

practice

Electric motors only consume the nominal current when the mechanical power is fully delivered. In the event of an overload, the current and thus the power can be several times higher (this is usually possible for a short time, but there is a risk of overheating). If the motor is not under load, it absorbs what is known as the no - load current . A substantial part of this is reactive current . When the motors are switched on or when they are started from standstill, a significantly higher current is often drawn from the network until the nominal speed is reached.

AC motors, luminaires with gas discharge lamps and transformers are inductive consumers, with them the absorbed current consists of an active and a reactive current component, which add up to the apparent current .

The rated current of AC and three-phase motors is the apparent current in each individual outer conductor . It is greater than the active current and can only be calculated from the output power and the voltage with the aid of the power factor.

literature

• Ralf Kories: Pocket book of electrical engineering: Basics and electronics . 8th edition. Harri Deutsch, 2008, ISBN 978-3-8171-1830-4 .