Separation of Core Losses in Transformer

Separation of Core Losses Calculation in a Transformer

The core loss of a transformer depends upon the frequency and the maximum flux density when the volume and the thickness of the core laminations are given. 

The core loss is made up of two parts

(i) Hysteresis loss 

Hysteresis loss in transformer is denoted as,

W_h = K_hƒ (B_m) ^1.6 watts

Hysteresis loss in a transformer occurs due to magnetization saturation in the core of the transformer.

Magnetic materials in the core will eventually become magnetically saturated when they are placed in a strong magnetic field, such as the magnetic field generated by an AC current.

(ii) Eddy current loss 

When an alternating magnetic field is applied to a magnetic material an emf is induced in the material itself according to Faraday’s Law of Electromagnetic induction. Since the magnetic material is a conducting material, these EMFs circulates currents within the body of the material. 

These circulating currents are called Eddy Currents. They will occur when the conductor experiences a changing magnetic field.

Eddy current loss in transformer is denoted as,

W_e = K_eƒ ²  K_f²ƒ B_m² watts

Where, 

K_h = Hysteresis constant.

K_e = Eddy current constant.

K_f= form constant.

Copper loss can simply be denoted as,

I_L²R₂′ + Stray loss

Where,

 I_L = I₂= load of the transformer, and R₂′ is the resistance of the transformer referred to as secondary.

If we carry out two experiments using two different frequencies but the same maximum flux density, we should be able to find the constants K_h and K_e and hence calculate hysteresis and eddy current losses separately.

You may know the details about the electrical transformer from the following articles:

 

1. Working Principle of Transformer;
2. Transformer Construction;
3. Core-type Transformers;
4. Shell-type Transformers;
5. Elementary Theory of an Ideal Transformer;
6. E.M.F. Equation of Transformer;
7. Voltage Transformation Ratio;
8. Transformer with losses but no Magnetic Leakage;
9. Transformer on No-load;
10. Transformer on Load;
11. Transformer with Winding Resistance but no Magnetic Leakage;
12. Equivalent Resistance;
13. Magnetic Leakage;
14. Transformer with Resistance and Leakage Reactance;
15. Simplified Diagram;
16. Total Approximate Voltage Drop in Transformer;
17. Exact Voltage Drop;
18. Equivalent Circuit Transformer Tests;
19. Open-circuit or No-load Test;
20. Separation of Core Losses;
21. Short-Circuit or Impedance Test;
22. Why Transformer Rating in KVA?;
23. Regulation of a Transformer;
24. Percentage Resistance, Reactance, and Impedance;
25. Kapp Regulation Diagram;
26. Sumpner or Back-to-back-Test;
    
27. The efficiency of a Transformer;
28. Condition for Maximum Efficiency;
29. Variation of Efficiency with Power Factor;
30. All-day Efficiency;
31. Auto-transformer;
32. Conversion of 2-Winding Transformer into Auto-transformer;
33. Parallel Operation of Single-phase Transformers;
34. Questions and Answers on Transformers;
35. Three-phase Transformers;
36. Three-phase Transformer Connections;
37. Star/Star or Y/Y Connection;
38. Delta-Delta or ∆/∆ Connection;
39. Wye/Delta or Y/ Connection;
40. Delta/Wye or ∆/Y Connection;
41. Open-Delta or V-V Connection;
42. Power Supplied by V-V Bank;
43. Scott Connection or T-T Connection;
44. Three-phase to Two-Phase Conversion and vice-versa;
45. Parallel Operation of 3-phase Transformers;
46. Instrument Transformers;
47. Current Transformers;
48. Potential or Voltage Transformers.