[2024] All About Losses in Transformer Explained

    The input and output power of a transformer is not equal because of the losses in a transformer. Losses in a transformer generally appears in the form of heat that increases temperature and reduces efficiency. There are mainly four types of losses in a transformer which are listed below.

• Core or iron or constant loss
• Copper or ohmic or resistive or variable loss
• Dielectric loss
• Stray loss

Core Losses

    Core or iron or constant loss occurs in the magnetic core of the transformer due to two different types of losses which are hysteresis loss and eddy current loss. This loss can be minimized using thin laminated silicon steel material separated by insulating materials.

Hysteresis loss

    Hysteresis loss in a transformer is caused due to continuous magnetization and demagnetization of the iron core. Due to the alternating current, the magnetic domain due to the core material continuously re-align themselves. This re-alignment process consumes energy and generate heat resulting hysteresis loss which is given by the following equation.

Ph = KηfVB1.6max

where, 

• kη is proportionality constant that depends on volume and quality of core material used
• f is the supply frequency
• Bmax is the maximum value of the flux density

Eddy Current Loss

    Eddy current is the loop current induced within the core when core get linked with the alternating magnetic field. This unwanted current generate heat according to the joules law of heating resulting power loss in the transformer known as eddy current loss.

    When magnetic flux get linked with a closed circuit, an EMF is induced that induces loop current. The amount of current induced depends on the induced EMF and circuit resistance and given by following equation.

Pe = KeVt2f2B2m

where,

• Ke is the proportionality constant that depends on nature of the material
• t is the thickness of the lamination
• f is the supply frequency
• Bm is the maximum flux density
• V is the volume of the core

    Eddy current loss can be minimized by constructing the core with thin lamination.

Copper Loss

    Copper or ohmic or resistive or variable loss occurs in the winding due to resistance of the primary and secondary winding of the transformer. This loss is directly proportional to the square of  the current flowing through the winding of the transformer and given by the following equation.

Pc = I21R1 + I22R2

where

• I1 and I2 are current flowing through primary and secondary winding
• R1 and R2 are the resistance of the primary and secondary winding.

    Copper loss vary with the load and hence known as variable loss.

Stray or Flux Loss

    The small portion of the magnetic flux do not linked with the secondary winding of the transformer but get dispersed in the surrounding air resulting the stray loss. These flux are leaked flux do not follow the desired path and may also result in eddy current induction in the conducting part of the transformer mainly iron core. It depends upon the core and winding design.

    Stray loss are generally small but contribute to the overall loss in a transformer. This loss depends on the following factors:-

1. leaked or fringing fluxes
2. High voltage transformer interfaces with environment
3. Air gaps and insulating material

Dielectric Loss

    Dielectric loss arises from the electric field developing near the insulating material and depends upon the nature of the insulating materials. This loss increases due to aged, low quality and wet insulating materials and given by the following equation.

Pd = V2𝜔Ctan(δ)

where,

• 𝜔 is the angular frequency
• C is the capacitance of the capacitor
• tan(δ) is the loss tangent of the dielectric material

Conclusion

    Hope, you have clearly understand about the losses in transformer, different types of the losses in transformer, Core or iron or constant loss, Copper or ohmic or resistive or variable loss, Dielectric loss and Stray loss. Make sure to leave your opinion and suggestion about this post in the comment section below.