Power-on rush

The switch-on rush is an effect that frequently occurs in electrical engineering. It occurs when a greatly increased inrush current occurs when an electronic device is switched on because the iron core is driven into saturation. This reduces the inductive reactance of the device and very high currents can flow for a short time. In the case of transformers or switching power supplies, these currents can sometimes be more than ten times the operating current. Reasons for this are, for example, an unfavorable phase angle of the mains voltage. In German, the term is also known as “inrush current”. Additional circuits or inrush current limiters can be used to counteract the effect of the inrush current.