Question

What is the factor affecting hysteresis loss?

Answer 1

Hysteresis loss is the energy lost due to the lag between changes in the magnetization of a material when it is exposed to a changing magnetic field. This loss happens in magnetic materials, like the core of transformers or motors, and results in heat generation. There are several factors that affect hysteresis loss:

### 1. **Magnetic Material Type**
   Different materials have different magnetic properties. The hysteresis loss is higher in materials with a larger **hysteresis loop**, which means the material has a higher coercivity and remanent magnetization. Soft magnetic materials (like silicon steel) have a narrow loop, leading to lower hysteresis loss compared to hard magnetic materials (like permanent magnets), which have wider loops.

### 2. **Magnetic Field Strength (Flux Density)**
   The strength of the magnetic field applied (also called **magnetic flux density** or B) influences the area of the hysteresis loop. A higher flux density results in a larger loop, which in turn increases the hysteresis loss. So, as the magnetic field intensity increases, the loss increases.

### 3. **Frequency of the Magnetic Field**
   The rate at which the magnetic field changes (its **frequency**) also affects the hysteresis loss. At higher frequencies, the material doesn't have enough time to fully magnetize and demagnetize, which increases energy loss. This is why transformers and motors operating at high frequencies experience more hysteresis loss.

### 4. **Temperature**
   As temperature increases, the properties of the material change. In general, as temperature rises, the coercivity of the material tends to decrease, meaning the material becomes easier to magnetize and demagnetize. However, at higher temperatures, some materials experience a higher loss due to increased resistance, which further enhances the hysteresis effect.

### 5. **Material Thickness**
   Thicker materials can increase the hysteresis loss, especially if the material is used in cores of transformers or motors. This is because thicker material may require more energy to change the magnetization in the entire volume of the material.

### 6. **Magnetic Field Alignment**
   If the magnetic field is not perfectly aligned with the material’s magnetization, more energy may be required to change the state of the material, leading to increased hysteresis loss. Proper alignment reduces these losses.

### Summary:
To minimize hysteresis loss, it's important to choose materials with low coercivity and narrow hysteresis loops (like soft magnetic materials), use lower flux densities, and design for lower operating frequencies when possible.