motorstroom

Motorstroom is the electrical current drawn by an electric motor, measured in amperes. It depends on the motor’s rated voltage, power, efficiency, and power factor, as well as the mechanical load connected to the shaft.

The motorstroom comprises two main components: the running current, which flows once the motor operates at steady speed under load, and the starting current (inrush) that occurs at energisation when the rotor is stationary. In DC motors there is also a stall current if the rotor cannot turn. The starting current is typically higher than the running current and varies with motor type, connection, and supply conditions.

On the motor nameplate the rated running current is specified. The starting current can be several times the running current, with exact values depending on whether the motor is connected in star or delta for three-phase systems and on the drive or control method used.

Electrical design must accommodate motorstroom because large starting surges affect conductors, switches, and protection devices. Voltage dips can disturb other equipment and may trigger protective relays. To manage motorstroom, several methods are used: soft starters, autotransformer starters, star-delta starting, and variable-frequency drives. Direct-on-line starting is simple but produces the largest surge; DC motors may use resistor or electronic controllers to limit current.

Practically, motorstroom planning relies on nameplate data, performance curves, and applicable standards. Monitoring starting currents helps protect equipment, ensure reliability, and optimize electrical installation.

See also: inrush current, starting current, induction motor, DC motor, soft starter, variable-frequency drive.