**Eddy Current Loss** and **Hysteresis Loss** are two types of core losses in electrical machines such as transformers, motors, and generators. Both of these losses occur in the core material, which is typically made of ferromagnetic substances. Here's a detailed explanation of what these losses are proportional to:
### 1. **Eddy Current Loss:**
Eddy currents are circulating currents induced in the core of the machine due to the alternating magnetic field. These currents cause resistive heating in the core, resulting in energy loss.
Eddy current loss (\(P_e\)) is proportional to:
\[
P_e \propto B^2 f^2 t^2
\]
where:
- \(B\) = Maximum flux density in the core (Tesla)
- \(f\) = Frequency of the alternating magnetic field (Hertz)
- \(t\) = Thickness of the core material (meters)
**Key Proportional Factors:**
- **Square of the Magnetic Flux Density (\(B^2\))**: Higher magnetic flux density causes stronger induced currents.
- **Square of the Frequency (\(f^2\))**: The faster the magnetic field alternates, the greater the eddy currents.
- **Square of the Thickness (\(t^2\))**: Thicker core laminations increase the eddy current loops, increasing the loss.
### 2. **Hysteresis Loss:**
Hysteresis loss is due to the lagging of magnetic domains in the core material as the magnetic field changes direction. This results in energy dissipation in the form of heat.
Hysteresis loss (\(P_h\)) is proportional to:
\[
P_h \propto B^n f
\]
where:
- \(B\) = Maximum flux density (Tesla)
- \(f\) = Frequency of the alternating magnetic field (Hertz)
- \(n\) = Steinmetz constant (typically between 1.5 and 2.5), which depends on the core material properties.
**Key Proportional Factors:**
- **\(B^n\) (Flux Density to the power of \(n\))**: As the magnetic flux density increases, hysteresis loss rises.
- **Frequency (\(f\))**: Higher frequency means more cycles of magnetization and demagnetization per second, increasing the energy lost.
### Summary:
- **Eddy Current Loss** is proportional to \(B^2 f^2 t^2\), meaning it depends heavily on flux density, frequency, and core thickness.
- **Hysteresis Loss** is proportional to \(B^n f\), where the flux density and frequency are the main factors, with \(n\) varying depending on the material used.
Reducing these losses typically involves using laminated cores (to minimize eddy currents) and materials with lower hysteresis properties (such as silicon steel).