Käynnistysvastus

Käynnistysvastus, which translates to "starting resistor" in English, is a component used in electric motor circuits. Its primary function is to limit the initial inrush current when a motor starts. Electric motors draw a significantly higher current during startup compared to their normal running current. This high current can stress the motor windings, the power supply, and other electrical components.

A käynnistysvastus is typically connected in series with the motor during the startup phase. This added resistance reduces the voltage across the motor terminals, thereby limiting the starting current to a more manageable level. As the motor accelerates and its internal impedance increases, the käynnistysvastus is gradually bypassed or switched out of the circuit, allowing the motor to receive full line voltage and operate at its designed speed.

The use of a käynnistysvastus is common in applications involving larger AC induction motors, particularly those that start under load or in situations where the power supply has limited capacity. By controlling the starting current, it helps to prevent voltage dips, reduce mechanical stress on the motor and connected equipment, and prolong the motor's lifespan. The design and resistance value of a käynnistysvastus are specific to the motor's power rating, voltage, and starting characteristics.