1. Transformer Agus Purwadi, Qamaruzzaman & Nana Heryana
Laboratorium Penelitian Konversi Energi Elektrik
Institut Teknologi Bandung

2. Transformer Definition
A transformer is a device that convert ac electric energy at one voltage level at another voltage level.

3. Transformer are important to modern life1.
Why
Thomas A. Edison (1882)
Power Distribution System : New York-USA ; 120 Vdc
Problems : Losses & Voltage Drop = inefficient
Example :
Inefficient

4. High Voltage
Efficient

5. Transformer are important to modern power systemLV HV
High Voltage
Low voltage
Inefficient
Efficient

6. Real Application on Power System
20 kV/380 V
380 V/20 kV

7. Teknik Tenaga Elektrik
Transformer
Frequency
Power Frequency , 50/60 Hz
Radio frequency, > 30 kHz
Teknik Tenaga Elektrik
Power Transformer
Instrument Transformer

8. 2. Type and Construction Of Transformer

9. 3. The Ideal Transformer
Turn ratio a

10. The Ideal Transformer
Turn ratio a

11. In term of phasor quantities
The Ideal Transformer
In term of phasor quantities

12. Power in ideal Transformer
Power input
Power input
ideal
Turn ratio equation

13. Power in ideal Transformer
Active power
reactive power
Apparent power

14. Evaluasi
Untuk memahami konsep trafo ideal berikan ke mahasiswa, contoh sederhana misalnya :
Cara mendapatkan tegangan sekunder y volt jika tegangan primernya x volt.
Arus sekunder b ampere pada tegangan y volt, cari arus primer a ampere pada tegangan X volt.
Ambil nilai x dan y yang bedanya sangat besar
Soal pada sistem 1 fasa dulu saja.

15. Impedance Transformer
ratio of the phasor voltage across it ti the phasor current

16. Impedance Transformerif

17. Theory of operation of real single-phase transformers
The basis transformer operation can be derived from Faraday’s law
Flux linkage

18. EMF equation of a transformer
Faraday law of electromagnetic induction
RMS Value

19. Transformer Losses Copper (I2R) losses Eddy current losses
Hysteresis losses
Leakage flux

20. The equivalent circuit of a transformer
the model of a real transformer

21. The equivalent circuit of a transformer

22. Phasor diagram corresponding – referred to primary

23. The equivalent circuit of a transformer

24. Test on transformers
Open-Circuit Test
Result : VOC IOC POC

25. Open-Circuit Test Result
Conductance of the core-loss resistor
Susceptance of the magnetizing inductor
Admittance
Magnitude admittance

26. Open-Circuit Test Result
Power Factor
Power Factor angle
Admittance

27. Test on transformers
Short-Circuit Test
Result : VSC ,ISC ,POC

28. Short-Circuit Test Result
Series impedance
Power Factor of the current
Lagging - Current angle (-),Impedance angle (+)
Therefore,

29. Short-Circuit Test Result
Series impedance
Admittance

30. Open-circuit test (on primary) Shots-circuit test (on primary)
2.2
The equivalent circuit impedances of a 20 kVA, 8000 / 240 V, 60 Hz transformer are to be determined. The open circuit test were performed on the primary side of the transformer, and the following data were taken :
Open-circuit test (on primary)
Shots-circuit test (on primary)
VOC = V
IOC = 0,214 A
POC = 400 W
VOC = V
IOC = 2,5 A
POC = 240 W

31. Solution

32. The per-unit system of measurement
In single-phase system :

33. Voltage Regulation & Efficiency

34. Step-down autotransformer

35. Power rating -autotransformer
SIO =Input and Output apparent powers
SW = apparent power in the transformer windings
Example
For example, a 5000 kVA autotransformer connecting a 110 kV system to a 138 kV system would have an NC/NSE turn of ratio of 110 : 28. Such an autotransformer would actually have windings rated at :

36. Three-phase transformer
A three-phase transformer bank composed of independent transformer
A three-phase transformer wound on a single three-legged core

37. Three-phase transformer connections
Wye-wye (Yy)
Wye-delta (Yd)
Delta-wye (Dy)
Delta-delta (Dd)

38. Wye-wye (Yy) Connection

39. Wye-delta (Yd) Connection

40. Delta-wye (Dy) Connection

41. Delta-delta (Dd) Connection

42. Test
A 50 kVA / 208 V, Dy distribution transformer has a resistance of 1 percent and reactance of 7 percent per unit.
What is the transformer’s phase impedance referred to the high-voltage side?
Calculate this transformer’s voltage regulation at full load and 0,8 PF lagging, using the calculated high-side impedance.
Calculate this transformer’s voltage regulation under the same conditions, using the per-unit system.

43. Instrument transformers
Potential transformer (PT)
Current transformers (CT)