Iron loss is caused by the eddy current loss and hysteresis loss generated by the transformer's iron core when the magnetic flux changes. Copper losses are resistive losses due to the current passing through the coils of the transformer.
The loss value of a transformer is usually specified in technical specifications or standards, such as the IEC 60076 standard. Manufacturers will determine the loss value of the transformer based on these regulations when designing and manufacturing the transformer.
Transformer losses mainly include two categories: iron loss (also called no-load loss) and copper loss (also called load loss). These losses directly affect the efficiency and performance of the transformer. Below I will describe in detail the causes and calculation methods of these two losses.
1. Iron loss
Iron loss is generated in the iron core of the transformer and mainly includes two parts: hysteresis loss and eddy current loss.
Hysteresis loss: When the iron core material is magnetized and demagnetized in an alternating magnetic field, energy loss occurs. This loss is called hysteresis loss. Hysteresis loss is related to the hysteresis loop area of the material, the frequency of the magnetic field and the maximum value of the magnetic flux density.
Eddy current loss: The alternating magnetic field in the iron core will generate eddy currents in the iron core material. These eddy currents generate heat energy under the resistance of the iron core material, thus causing losses. Eddy current losses are proportional to the resistivity of the material, the thickness of the core, the frequency of the magnetic field and the square of the magnetic flux density.
2. Copper loss
Copper losses are generated in the windings of transformers, mainly due to heat losses caused by resistance in the windings.
Load Loss: When current passes through the transformer winding, the resistance of the winding causes energy loss, which increases in proportion to the square of the load current. Therefore, when the transformer load increases, the copper losses also increase.
Loss reduction
In order to reduce these losses, manufacturers have taken various measures:
- Use silicon steel sheets with high magnetic permeability and low hysteresis loss to reduce iron loss.
- Adopt subdivided iron core structure to reduce eddy current losses.
- Use highly conductive materials and optimized winding design to reduce copper losses
Standards and Regulations
The loss value of the transformer usually needs to comply with the regulations of the International Electrotechnical Commission (IEC) or other relevant standards bodies. For example, the IEC 60076 series of standards details methods for transformer design, testing and loss assessment.
Through these measures and calculations, transformer manufacturers can design high-efficiency transformers that meet the needs of both industry and civilian applications.
