Hysteresis loss

Definition

Hysteresis loss refers to the energy dissipated as heat when a magnetic material is magnetized and demagnetized cyclically. This phenomenon occurs due to the lagging of the magnetization behind the applied magnetic field, which results in a loop on a magnetic hysteresis curve. The energy lost is directly related to the material's magnetic properties and can significantly affect the efficiency of electrical devices, especially those involving alternating current.

5 Must Know Facts For Your Next Test

1. Hysteresis loss is influenced by the material's coercivity, which is its resistance to being demagnetized.
2. Materials with low hysteresis loss, such as silicon steel, are preferred for electrical devices to enhance efficiency.
3. The area of the hysteresis loop on the B-H curve quantitatively represents the hysteresis loss per cycle.
4. Hysteresis loss increases with frequency; thus, devices operating at higher frequencies tend to experience greater energy losses.
5. Minimizing hysteresis loss is crucial in designing transformers and inductors, as it directly impacts their overall performance and heat generation.

Review Questions

• How does hysteresis loss impact the efficiency of electrical devices that utilize magnetic materials?
  • Hysteresis loss negatively impacts the efficiency of electrical devices by converting some of the input energy into heat during each cycle of magnetization. This energy dissipation occurs as the material is magnetized and demagnetized, leading to a reduction in usable energy. Devices like transformers and inductors need to minimize this loss to improve their performance and reduce overheating, making material selection critical for achieving high efficiency.
• Compare and contrast hysteresis loss with eddy current loss in terms of their effects on magnetic materials.
  • While both hysteresis loss and eddy current loss contribute to energy dissipation in magnetic materials, they arise from different mechanisms. Hysteresis loss is due to the lagging of magnetization behind the applied magnetic field during cyclical magnetization. In contrast, eddy currents are induced circulating currents caused by changing magnetic fields within conductors. While hysteresis loss is more dependent on the magnetic properties of materials, eddy current loss can be minimized by using laminations or insulating materials to reduce current loops.
• Evaluate the significance of minimizing hysteresis loss in the context of modern electrical engineering applications.
  • Minimizing hysteresis loss is increasingly significant in modern electrical engineering as it directly influences energy efficiency and thermal management in devices like transformers, electric motors, and inductors. With rising demands for energy-efficient systems and sustainable practices, engineers focus on selecting materials with lower hysteresis losses to enhance device performance. Moreover, reducing these losses contributes to less heat generation, improving reliability and lifespan while also decreasing operational costs for industrial applications.

Related terms

Magnetic hysteresis: The phenomenon where the magnetization of a material depends on its magnetic history, often represented by a loop on a B-H curve.

Core losses: Energy losses in magnetic materials used in transformers and inductors, including hysteresis loss and eddy current loss.

Eddy currents: Circulating currents induced in conductive materials when exposed to changing magnetic fields, leading to energy loss and heating.