- Trending Categories
- Data Structure
- Networking
- RDBMS
- Operating System
- Java
- iOS
- HTML
- CSS
- Android
- Python
- C Programming
- C++
- C#
- MongoDB
- MySQL
- Javascript
- PHP

- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who

The power losses which occur in a transformer are of two types −

- Core or Iron Losses (
*P*)_{i} - Copper Losses or I
^{2}R Losses (*P*)_{cu}

The losses in a transformer appears in the form of heat which increases the temperature and reduces the efficiency.

The *iron losses* occur in the core of the transformer due to the alternating flux. These losses consist of hysteresis loss (*P _{h}*) and eddy current loss (

$$\mathrm{P_{i}=P_{h}+P_{e}}$$

The hysteresis and eddy-current losses are given by,

$$\mathrm{Hysteresis\:loss,\: P_{h} \:= \:k_{h}f_{max}^{1.6} \:1.6 V \:Watt}$$

$$\mathrm{Eddy\:current \:loss, \:P_{e} \:= \:K_{e}f^2B_{max}^{2}t^2 V \:Watt}$$

Where,

**k**_{h}= hysteresis coefficient,**k**_{e}= eddy current coefficient,**f**= supply frequency,**B**_{max}= maximum flux density,**t**= thickness of each lamination, and**V**= volume of core.

The exponent 1.6 of the maximum flux density is known as *Steinmetz coefficient*. Now, the iron losses can also be written as,

$$\mathrm{P_{i}\:=\:k_{h}f_{max}^{1.6} \:1.6 V \:+\:K_{e}f^2B_{max}^{2}t^2 V}$$

As we can see, both the hysteresis and eddy current losses are the function of maximum flux density in core, supply frequency and volume of the core material which is constant. Since, the transformer is connected to a source of constant frequency so that both f and B_{max} are constant. Therefore, *the iron or core losses are practically constant for a transformer at all loads*. The iron losses of a transformer can be determined by *open-circuit test*.

In order to reduce the hysteresis loss, the core should be made up of high silicon content steel whereas to minimise the eddy current loss, the core is built-up by using thin laminations.

The *copper losses* take place in the primary and secondary windings due to resistances of windings and can be determined by *short circuit test*.

The total copper loss (P_{cu}) in a transformer is given by,

$$\mathrm{P_{cu}\:=\: Primary \:winding \:cu \:loss \:+ \:Secondary \:wind\:ng\: cu\: loss}$$

$$\mathrm{⇒\:P_{cu}\:=\:I_{1}^{2}R_{1}\:+\:I_{2}^{2}R_{2}}$$

Since,

$$\mathrm{N_{1}I_{1}\:=\:N_{2}I_{2}}$$

$$\mathrm{⇒\:I_{1}\:=\:\frac{N_{2}}{N_{1}}I_{2}}$$

$$\mathrm{\therefore\:P_{cu}\:=\:(\frac{N_{2}}{N_{1}})^2I_{2}^{2}R_{1}\:+\:I_{2}^{2}R_{2}\:=\:I_2^2((\frac{N_{2}}{N_{1}})^2R_{1}+R_{2})\:=\:I_{2}^{2}R_{02}}$$

Also,

$$\mathrm{P_{cu}\:=\:I_{1}^{2}R_{1}\:+\:I_{2}^{2}R_{2}\:=\:I_{1}^{2}R_{1}+(\frac{N_{1}}{N_{2}})^2I_{1}^{2}R_{1}\:=\:I_{1}^{2}R_{01}}$$

Therefore,

$$\mathrm{P_{cu}\:=\:I_{2}^{2}R_{02}\:=\:I_{1}^{2}R_{01}}$$

**Stray Loss –**A practical transformer has leakage reactance, which produces eddy currents in the conductors, transformer tank and in other metallic parts which causes the losses in the transformer. These losses are called*stray losses*.**Dielectric Loss –**The dielectric losses occur in the insulating material (transformer oil or solid insulation) of the transformer. The dielectric loss is significant only in high voltage transformers.

- Related Questions & Answers
- Losses in DC Machine – Iron Loss, Copper Loss and Mechanical Losses
- Losses and Efficiency of an Alternator
- Power Flow Diagram and Losses of Induction Motor
- Electric Machine Losses and Efficiency with Examples
- Output of an Autotransformer and Saving of Copper in Transformer
- Construction of a Transformer – Core Type and Shell Type
- EMF Equation of Transformer – Turns & Transformation Ratio of Transformer
- Delta-Star Connection of Transformer – Three-Phase Transformer Connection
- How to appropriately plot the losses values acquired by (loss_curve_) from MLPClassifier? (Matplotlib)
- Transformer Inrush Current – Calculation and Theory
- Approximate Voltage Drop in a Transformer and Voltage regulation of a Transformer
- Single Phase Transformer – Construction and Working Principle
- Comparison of Fiber Optics and Copper Wire
- Wattmeter – Types and Working Principle
- MOSFET – Types and Working Principle

Advertisements