Exact Voltage Drop of a Transformer

How to Calculate the Exact Voltage Drop of a Transformer?

Transformer voltage drop is important to know because it is one of the factors that affect the performance of an electrical system where it is installed. 

There are two most common methods to calculate the transformer voltage drop-

1. Approximate Method;
2. Exact Method.

The Approximate Method of Transformer Voltage drop calculation in detail is explained in another article.

Let's explain the Exact Method of Transformer voltage drop calculation below:

where:

E_VD – Voltage drop, line-to-neutral, volts

Es – Source voltage, line-to-neutral, volts

I – Line (Load) current, amperes

R – Circuit (branch, feeder) resistance, ohms

X – Circuit (branch, feeder) reactance, ohms

cosθ – Power factor of load, decimal

sinθ – Reactive factor of load, decimal

Transformer voltage drop:

Exact method If the receiving end voltage, load current, and power factor (PF) are known.

E_R is the receiving end voltage.

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.