tyhjäkäyntihäviöt

Tyhjäkäyntihäviöt, or no-load losses, refer to the energy dissipated in electrical equipment when it is energized but not supplying any useful output power. These losses are primarily associated with transformers and rotating electrical machines like motors and generators.

In transformers, tyhjäkäyntihäviöt are mainly due to hysteresis and eddy currents in the iron core. Hysteresis loss occurs because the magnetic domains in the core material repeatedly realign themselves with the alternating magnetic field, consuming energy. Eddy currents are circulating currents induced in the conductive core material by the changing magnetic flux, which dissipate energy as heat due to the core's resistance. These losses are dependent on the magnetic properties of the core material and the frequency of the applied voltage.

For rotating machines, tyhjäkäyntihäviöt include core losses (similar to those in transformers), friction losses in bearings, and windage losses due to air resistance on the rotating parts. These losses occur even when the machine is running at no load.

Tyhjäkäyntihäviöt are a significant factor in the overall efficiency of electrical equipment. While they are present whenever the equipment is powered, their impact on efficiency is more pronounced at lighter loads. Minimizing these losses through careful material selection, design optimization, and proper maintenance is crucial for improving energy efficiency and reducing operating costs. Understanding and quantifying tyhjäkäyntihäviöt is essential for accurate performance evaluation and system design.