Transformer Losses | Core loss | Copper loss

what are Transformer Losses?

The transformer is a fixed type device. Therefore, there is no wastage due to friction. Transformer loss refers to all that can be seen in no-load and full-load conditions.

types of losses in transformer

Here are two main types of transformer loss

 Core loss

 Copper loss


Core loss in a transformer (Core loss)

Core loss or iron loss is the sum of eddy current loss and hysteresis loss. That is, core loss`P_c=P_h+P_c`

The core loss is fixed for any transformer. The core loss remains the same in any condition from no-load to full-load of the transformer.

Because the core loss for the transformer is roughly proportional to the square of the mutual flux. That is, core loss `\phi_m^2` (Roughly).

A is established between the mutual flux core and its value is not related to the load. The mutual flux depends on the amount of supply voltage applied to the primary.

when the applied voltage decreases and increases, the mutual flux decreases, and increases. If there is no change in the applied voltage, there is no change in the mutual flux.

As a result, core loss remains the same and does not depend on load reduction and increase.

On the other hand, as the load decreases and increases, the load current becomes less and more, and accordingly, copper loss becomes less and more.

Core loss Two types: -

Eddy current loss

Hysteresis loss

Hysteresis and Eddy current losses

Eddy current loss in transformer

When the current flowing through the coil of an electromagnet changes. Then the magnetic field around it also changes This variable flux cuts the wire of the coil, creating voltage in the coil This flux also cuts the same core As a result,

a current is also rotated in this core, called eddy current The core resistance is interrupted when the eddy current flows through the core material. The waste that causes it is called eddy current loss.

Eddy current loss formula


`K_e`= The number of constant. It depends on the size of the core used, the thickness of the lamination, and the resistivity of the steel (core)

f= Frequency

t= The lamination is thick

Setting the value of flux density to Bm in Equation 1

`\Rightarrow P_C=K_ef^2t^2(\frac{E^2}{f^2})=K_2t^2E^2`

Ways to reduce Eddy ​​current loss

This loss can be reduced by using a thin core of bright resistive magnetic material.

Hysteresis Loss

The variable current changes direction every half cycle As a result, the magnetic flux changes periodically to the maximum positive meaning once and the maximum negative value again.

This periodic change of positive mean and negative mean causes the core magnets to change direction again and again.

Power is expended as a result of so much collision. This expended energy appears as heat, this is called hysteresis loss.

Hysteresis loss formula

`\Rightarrow P_h=K_hfB_m1.6W`--------(1)

`K_h`= The number of constant. It depends on the size and quality of the core used

`B_m`=The maximum flux density of the core

f= Frequency

We know,
`\phi_m=B_m\times A=\frac{E\times10^8}{4.44fN}`
`B_m=(\frac{10^8}{4.44NA})\frac Ef`
 A = Area of the core

The N and A constants of the transformer
`B_m=K\frac Ef` `\lbrack K=\frac{10^8}{4.44NA}\rbrack`

Let's put this into equation 1,

`\Rightarrow P_h=K_hfk(\frac{E^{1.6}}{f^{1.6}})=K_1(\frac{E^{1.6}}{f^{1.6}})`-----------(2)

Ways to reduce hysteresis loss: -
This loss can be reduced by using a high-quality magnetic steel core.

Effects of hysteresis loss: -
The higher the hysteresis loss, the more heat will be generated As a result power loss will increase and insulation will be more damaged.

Copper loss in transformer(Copper loss)

The loss due to the ohmic resistance of the primary and secondary windings of the transformer is called copper loss.

Copper loss is related to the load. As the load increases, its loss increases. A loss is determined by `I^2R`. Copper loss is proportional to the square of the current.

Copper loss formula

That is,

`P_C\sim I^2`

`P_C\sim KVA^2`

The amount of copper loss is found from the short circuit test. In the case of the transformer, copper is lost at winding. In that case total copper loss = `{I^2}_PR_P+{I^2}_SR_S`
If the load is less or more than the rated KVA of the transformer, the copper loss decreases or increases very fast.

For example - a transformer rated KVA will have 100W, copper loss at ½ load, ¾ load and double load at copper loss respectively.

Copper loss Two types: -

Copper loss in the primary winding 

Copper loss in the secondary winding

FAQ In Transformer Losses

Q1.What is Eddy Current Loss?

Ans: The dissipation caused by the core resistance when the current flows through the core is called, Eddy current loss.

Q2.How to reduce the hysteresis loss of the transformer?

Ans: Uses high-quality magnetic seat cores.

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