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Difference Between Iron Loss and Copper Loss

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An Introduction: What is Iron Loss?

The quantity of weight lost over a specific time period is known as "Iron Loss". It is also known as "Weighing Loss". Iron tends to lose weight over time because of the nature of its magnetic force, which makes it easier for a magnet to draw it than other kinds of metal.

The types of iron materials utilised in the machine are often the main cause of iron loss. For instance, iron materials with chromium tend to lose weight more quickly than iron without chromium. Different techniques, such as differential weighing and differential weighing with flow rate control, can be used to measure iron loss. The number that comes after "Weighing" designates its classification.

Two factors contribute to the iron losses in the transformer's iron core.

  • Hysteresis loss

  • Eddy current Loss

Last updated date: 22nd Sep 2023
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What in a Transformer is Hysteresis Loss?

When the primary winding of the transformer receives alternating voltage, the core undergoes a process of magnetization and demagnetization. The magnetic core loses heat as a result of its cyclic reversal. Hysteresis loss is the term for the heat loss occurring in the core as a result of repetitive magnetization demagnetization.

Factors affecting hysteresis loss include

  • Flux Density

  • The Volume of Core Material

Formula for Hysteresis loss can be shown as follows:

$P_{h}= \eta B_{m}^{1.6}fV$

Where, Ph=Hysteresis loss

\eta=Steinmetz hysteresis coefficient

Bm=Maximum flux density

What does a Transformer's Eddy Current Loss Mean?

The magnetic core is traversed by the flux generated by the primary winding, which connects to the secondary winding. A portion of the flux interacts with the core and causes various levels of voltage there. Current flows between two sites in the core when there is a voltage differential between those two points. It is called the eddy current. Energy lost in the core is limited by the resistance of the core material.


Formula for Eddy current loss is as follows:

$P_{e}= K_{e}B_{m}^{2}f^{2}t^{2}V$

Where, Pe= Eddy current loss(watt)

              Ke= Eddy current constant

              Bm= Maximum flux density

              f= frequency of supply

              t= thickness of lamination(m)

              V= volume of the material (m3)

Iron loss thus becomes the total of hysteresis loss(Ph) and eddy current loss(Pe).

What is Copper Loss: An in Depth Analysis

Copper Loss is the amount of volume lost over a specific time frame. Either fixed weighing or electronic weighing can be used to quantify volume. The copper loss would be zero in a perfect world, but most people are aware that there are numerous reasons why this is never the case. There are numerous ways to quantify it, depending on the requirements.  How frequently you open the valve over the course of a given amount of time is one of the primary factors in copper loss. Your losses will increase as you open it more. Frequent opening and closing of valves causes them to wear out and degrade in quality more quickly than valves that are opened less frequently. 

Copper Loss in the primary winding of the transformer is given as follows:


Where, Pcup= Copper loss in transformer primary winding

I1= Current in transformer primary winding

R1= Resistance of transformer primary winding

Copper loss in the secondary winding of the transformer is given as follows:


Where, Pcus= Copper loss in transformer secondary winding

I2= current in transformer secondary winding

R2= resistance of secondary winding

Total copper losses in a transformer is the sum total of copper losses in primary winding(Pcup )and secondary winding(Pcus).

Characteristics of Iron Loss and Copper Loss: 

Ohmic resistance of the transformer windings is the cause of copper loss. The relationship between Copper loss and square of current, which depends on the load, is obvious. As a result, the load affects the copper loss in the transformer. The alternating magnetic flux that passes through the transformer's magnetic core causes iron loss. Because of this, the iron loss is also known as core loss. Although iron loss and copper loss are two distinct entities, understanding the distinctions between them is essential to understanding the bigger picture. 

Many people who are unaware of the distinction frequently mistake copper loss for iron loss. It's necessary to be aware of this difference and keep track of it occasionally since it's essential to comprehend it in order to comprehend how your system functions. When they don't know how to measure it, a lot of individuals become perplexed. While copper loss is often assessed by volume, iron loss is typically measured by weight. They are significantly different in terms of how they are measured even though they are both parts of a machine.

Iron Loss and Copper Loss Difference:



Iron loss

Copper loss

Material loss

Generally, it is the loss of iron(Fe) material in the transformer.

Apart from copper loss, there can also be a loss of liquid material too inside the transformer.

Measurement criteria

It is measured through weight.

It is measured by volume.

Time period of the loss

It is in general a permanent loss.

It is only a temporary loss.

Subtypes of losses 

Iron losses can be further divided into two types of losses i.e., hysteresis loss and eddy current loss.

Copper loss has two components i.e., loss in primary winding and loss in secondary winding.

Other names

Iron loss is also called core loss.

Copper loss is also called Ohmic Loss.


Knowing how iron loss and copper loss are monitored and used in your machine is crucial since there is a significant difference between the two. It's necessary to be aware of this difference and keep track of it occasionally since it's essential to comprehend it in order to comprehend how your system functions. Moreover, by leaving liquids within the machine for an extended period of time, you may check for iron loss.

FAQs on Difference Between Iron Loss and Copper Loss

1. What is iron loss and copper loss?

The quantity of weight lost over a specific time period is known as Iron Loss. Flux density changes in the transformer core are the reason for the iron loss.  Mechanical energy is first converted from electrical energy. Magnetic energy travels through the magnetic core. Energy is lost during the core's demagnetization and magnetization. Copper Loss is the amount of volume lost over a specific time frame. The transformer winding is the source of the copper loss. A transformer's primary and secondary windings have a specific resistance. The wire diameter and number of turns affect the winding resistance. The current flowing in the primary and secondary windings is what causes the heat loss in the winding. The heat loss in the coil is known as copper loss.

2. What are the factors affecting eddy current losses in the transformer?

Eddy current losses are a consequence of Farady's law, which states that "Any change in the environment of a coil of wire will cause a voltage to be induced in the coil, regardless of how the magnetic change is produced." Consequently, a voltage, or EMF, is created in the coils when a motor core rotates in a magnetic field. Eddy currents, which are circulating currents that are caused by this produced EMF, flow as a result. Eddy current loss is the name for the power loss brought on by these currents. Factors affecting eddy current losses are attributed to maximum flux density in the core, supply frequency, thickness of the lamination, volume of the core material and resistivity of the core.

3. What are the ways of reducing hysteresis loss inside the transformer?

Some ways through which hysteresis loss can be mitigated inside a transformer include selection of the specific core material which has less magnetic flux density and operating the transformer at a rated voltage and frequency. Also using alloys like mumetal or silicon steel for core material can greatly reduce hysteresis loss.