Idle losses

Open-circuit losses (also known as iron losses) are losses that occur in electrical devices when they are operated at voltage without a load being connected.

They mainly occur in the magnetic core due to hysteresis and eddy current losses that occur during periodic remagnetization. In transformers, these losses already occur when the rated voltage is applied in no-load operation and are largely independent of the load.

No-load losses occur in transformers, electric motors and power supply units , for example. In the case of power supply units, they are caused by magnetic components, electronic circuits and standby consumption, among other things.

The power consumed is mainly converted into heat. It is therefore important to keep idle losses to a minimum in order to improve the energy efficiency of electrical appliances.