Question

What are eddy current and hysteresis losses proportional to?

Answer 1

Eddy current and hysteresis losses are two types of energy losses that occur in magnetic materials, particularly in transformers, electric motors, and other devices that involve alternating magnetic fields. Here's what they are proportional to:

Eddy Current Losses:

Eddy current losses are caused by circulating currents (called eddy currents) that are induced in a conductor when it is exposed to a changing magnetic field. These currents cause energy to be dissipated in the form of heat.

1. Proportional to:
   

  1. Square of the frequency (f): As the frequency of the alternating magnetic field increases, the eddy current loss increases.
  2. Square of the magnetic flux density (B): Higher magnetic flux density leads to stronger induced eddy currents and, therefore, higher losses.
  3. Thickness of the conductor (d): The greater the thickness of the material, the more room there is for the eddy currents to form, leading to higher losses.
  4. Resistivity of the material (ρ): Higher resistivity leads to less eddy current loss, because the current finds it harder to flow in the material.

Hysteresis Losses:

Hysteresis losses occur when a magnetic material is repeatedly magnetized and demagnetized. The energy required to change the magnetization of the material during each cycle is dissipated as heat.

1. Proportional to:
   

  1. Frequency (f): Higher frequency results in more cycles of magnetization and demagnetization, leading to higher losses.
  2. Magnetic flux density (B): The greater the flux density, the more energy is required to magnetize and demagnetize the material, leading to higher losses.
  3. Volume of the magnetic material: Larger volumes of material experience more hysteresis loss, as more material needs to be magnetized.
  4. Material properties: Materials with higher coercivity (resistance to changing magnetization) tend to have higher hysteresis losses.

In summary:

1. Eddy current losses are proportional to the square of the frequency, the square of the flux density, the thickness of the conductor, and inversely proportional to the resistivity of the material.
   

1. Hysteresis losses are proportional to the frequency, the magnetic flux density, and the volume of the material.