The power delivered to the transformer’s input terminal must match the power delivered to the transformer’s output terminal since a perfect transformer is extremely efficient and does not experience energy losses.
As a result, there are no energy losses in an ideal transformer, & the input & output powers are equal to one another.
However, in reality, because of internal electrical losses, the transformer’s input & output powers will not be equal.
Since it has no moveable elements, it is a static device; therefore, we cannot see mechanical losses, but electrical losses, such as those caused by copper and iron, will happen.
The purpose of this post is to provide an overview of many types of losses that can occur in transformers.
Types of Losses in Transformer
The losses that occur in transformers can take many different forms, including:
- Iron Loss,
- Copper Loss,
- Hysteresis Loss,
- Eddy Current Loss,
- Stray Loss, and
- Dielectric Loss.
The hysteresis losses are caused by variations in magnetization in the transformer’s core, whereas the copper loss is caused by the transformer’s winding resistance.
The different types of transformer losses are detailed below.
1). Iron Losses
Iron losses are created by alternating flux in the transformer’s core, which is generally referred as core loss. Iron loss is further classified as hysteresis & eddy current loss.
2). Hysteresis Loss
The transformer’s core is magnetized alternately, and a hysteresis loop is formed for every cycle of emf.
Power is dissipated in form of heat, known as hysteresis loss, and is represented by the equation below:
Ph=KηB1.6maxfV (watts)
Where
Kη – Proportionality constant that varies with core volume & quality,
f – Supply frequency,
Bmax – Peak flux density.
The iron or core losses can be reduced by constructing the transformer’s core from silicon steel.
3). Eddy Current Loss
When the flux connects to a closed circuit, an emf is induced in circuit, and current flows; the value of the current is determined by the amount of emf around the circuit and the circuit’s resistance.
Because the core is constructed of a conducting material, the EMFs circulate currents throughout the material’s body.
Eddy currents are the collective term given to these types of circulation currents.
They will happen when the conductor is exposed to a changing a magnetic field.
An I2R loss in magnetic material is referred to as an Eddy Current Loss. This loss is caused by these currents, which are not responsible for any major activity.
Eddy current loss is reduced by using thin laminations in the core.
The equation for eddy current loss is:
Pe = KeB2mt2f2V (watts)
Where,
Ke – Eddy current coefficient. Its value depends on type of magnetic material, such as the volume & resistivity of the core material, the thickness of laminations.
Bm -Highest value of flux density in wb/m2.
t – Lamination thickness in meters
f – Magnetic field reversal frequency in Hz
V – Magnetic material volume in m3
4). Copper Loss (or) Ohmic Loss
The losses are occurred by transformer windings’ ohmic resistance. Assume I1 & I2 are the primary & secondary currents. If R1 & R2 are the resistances of the primary & secondary windings, then the copper losses will be I12R1 & I22R2, respectively.
Pc = I12R1 + I22R2
As a result, the total copper losses will be calculated as transformer-losses.
These losses fluctuated with the load and are hence referred to as variable losses.
Copper losses vary with the load current squared.
5). Stray Loss
Stray losses arise as a result of the presence of a leaky field. These losses are insignificant in comparison to the iron & copper losses, thus they can be ignored.
6). Dielectric Loss
Dielectric loss occur in the transformer’s insulating material, which is found in the oil (or) solid insulations. When the oil deteriorates, the solid insulation is broken, or the quality of the oil drops, the transformer’s efficiency affected.
According to the preceding description, a transformer has both constant and variable losses. Thus, we can divide transformer losses into two categories: constant losses & variable losses.
Thus, the overall losses in transformer are sum of constant & variable losses,
i.e., Transformer Total losses = Constant Losses + Variable Losses.
