1. TESTING AND MAINTENANCE OF POWER TRANSFORMER
University of Turkish Aeronautical Association
Faculty of engineering EEE department
TESTING AND MAINTENANCE OF POWER TRANSFORMER
Supervision
Prof. Dr. Ibrahim Mahariq
Department of Electrical Engineering
TAA. University
Ankara , Turkey
Presented by
Othman Al Darraji
Department of Electrical Engineering
TAA. University
Ankara , Turkey
Presented by
Omar Saadi Alshear
Department of Electrical Engineering
TAA. University
Ankara , Turkey
Turkey – Ankara
TESTING AND MAINTENANCE OF POWER TRANSFORMER

2. DEFINITION OF THE TRANSFORMER
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

3. WHAT IS TRANSFORMER?
Transformer is a static device which transforms A.C electrical power from one voltage to another
Voltage keeping
The frequency same by
Electromagnetic induction.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

4. WHAT IS TRANSFORMER? IRON CORE
TESTING AND MAINTENANCE OF POWER TRANSFORMER

5. DEFINITION OF THE TRANSFORMER
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

6. TEST REQUIREMENTS 1- NAME PLATE FOR TRANSFORMER S.N: 925 554 1=50KVA
TESTING AND MAINTENANCE OF POWER TRANSFORMER

7. 2-TESTING DEVICES TEST REQUIREMENTS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

8. 4 - MECHANICAL EQUIPMENT
TEST REQUIREMENTS
3- SAFETY EQUIPMENT
4 - MECHANICAL EQUIPMENT
TESTING AND MAINTENANCE OF POWER TRANSFORMER

9. DEFINITION OF THE TRANSFORMER
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

10. TESTING OF TRANSFORMER
Types of testing
1- Routine tests
2- Type tests
3- Special tests
TESTING AND MAINTENANCE OF POWER TRANSFORMER

11. TESTING OF TRANSFORMER
1-ROUTINE TESTS
1.1- Measurement of voltage ratio
1.2-Vector group verification
1.3-Measurement of winding resistance
1.4-Impedance voltage test(z)
1.5-Dielectrics Test
A-Measurement of insulation resistance.
B- Dissipation power factor / insulation power factor (tan∂)
C- OIL TEST
TESTING AND MAINTENANCE OF POWER TRANSFORMER

12. THESE TESTS ARE CARRIED OUT ON ONE TRANSFORMER OF THE LOT.
TESTING OF TRANSFORMER
2- TYPE TESTS
THESE TESTS ARE CARRIED OUT ON ONE TRANSFORMER OF THE LOT.
2.1- All routine tests.
2.2- Additionally following tests are included in type tests.
A- Lightening impulse test.
B- Temperature rise test.

13. TESTING OF TRANSFORMER
3-SPECIAL TESTS
3.1- Measurement of zero Phase sequence.
3.2- Measurement of acoustic noise level.
3.3- Measurement of harmonics of the no load current.
3.4- Magnetic balance test.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

14. DEFINITION OF THE TRANSFORMER
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

15. Transformer Breakdowns
TESTING AND MAINTENANCE OF POWER TRANSFORMER

16. Sources of faults in transformer
TESTING AND MAINTENANCE OF POWER TRANSFORMER

17. TESTING AND MAINTENANCE OF POWER TRANSFORMER

18. Apply Tests Routine on Power Transformer
1-ROUTINE TESTS
Apply Tests Routine on Power Transformer
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYnd11
TESTING AND MAINTENANCE OF POWER TRANSFORMER

19. 1-1-Measurement of voltage ratio
1- This test measures the voltage ratio as per the customer’s requirement.
2- V1/V2 = N1/N2
3-The voltage ratio is equal to the turns ratio in a transformer. Using this principle, the turns ratio is measured with the help of a turns ratio meter. If it is correct , then the voltage ratio is assumed to be correct.
4- apply the rated ratio for all tab (1-17).
5-apply the rated ratio for (132 kv,33kv 11kv)
6- Equipment used : Transformer Turns Ratiometer ( T T R)
TESTING AND MAINTENANCE OF POWER TRANSFORMER

20. 1-1-Measurement of voltage ratio
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
Rated ratio (Ynd11)H.V-L.V=( 132 / √3 ) / 11.5= FOR TAP (9)
Tap pos.
TAP Voltage
(kv)
(A-N) / (a-c)
(Measured value)
(B-N) / (b-a)
(C-N) / (c-b)
Rated Ratio
(Rated value ) 1
145.2 / 11.5 9 10 11
132.0
(132 ⁄ √3) ⁄ 11.5 = 6.627 17
118.8
TESTING AND MAINTENANCE OF POWER TRANSFORMER

21. TEST: 1-1-Measurement of voltage ratio
VECT. GROUP: Ynd11 FOR H.V – L.V b c C B A
L.V
H.V
M.V
Ratio meter n
TR.
TR.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

22. The no-load deviation of the turn ratios should be ≤ % 0,5
1-1-Measurement of voltage ratio
APPLLY THIS LAW
The no-load deviation of the turn ratios should be ≤ % 0,5
TESTING AND MAINTENANCE OF POWER TRANSFORMER

23. The use of modern equipment
1-1-Measurement of voltage ratio
The use of modern equipment .
TTR (Transformer Turns Ratio)
TESTING AND MAINTENANCE OF POWER TRANSFORMER

24. 1-2-Vector Group Verification
This test is very important for an engineer to figure out directional connectivity for transformers.
(( Dy11 ,Yd11, Dy1,Yd1))
TESTING AND MAINTENANCE OF POWER TRANSFORMER

25. Dy11
Yd11
TESTING AND MAINTENANCE OF POWER TRANSFORMER

26. Dy1
Yd1
TESTING AND MAINTENANCE OF POWER TRANSFORMER

27. 1-2-Vector Group Verification
Steps to implement the test
STEP 1
Connect H.V
STEP 2
S.C
STEP 3
Take V
B-b , B-c ,C-b , C-c
TESTING AND MAINTENANCE OF POWER TRANSFORMER

28. 1-2-Vector Group Verification
C-b > C-c ≈ B-b ≈ B-c
B-c > B-b ≈ C-c ≈ C-b
B-c ≈ C-b>B-b ≈ C-c
Dy11
Dy1
Dd0
Yd11
Yd1
Yy0
TESTING AND MAINTENANCE OF POWER TRANSFORMER

29. 1-3-Measurement of winding resistance
D.C RESISTANCE
This test measures the resistance of the H.V , M.V& L.V winding. The values of resistance should be balance for all three phases and should match the designed values.
Equipment used : Digital resistance meter.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

30. 1-3-Measurement of winding resistance
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
FOR H.V, USES TAP POS
FOR M.V , USES TAP POS
FOR L.V , USES TAP POS. 1
Tap pos.
A-N
ohm
B-N
C-N
Resistance 3-ph
Oil Temp
Rest. At 75C˚ 1 9
0.4108
0.4104
0.4192
1.2305
19C˚
1.5023 17
TESTING AND MAINTENANCE OF POWER TRANSFORMER

31. 1-3-Measurement of winding resistance
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
WHEATSTON BRIDGE a N
WIND. REST. FOR H.V b c C B A
L.V
H.V
M.V
WHEATSTON BRIDGE n
TR.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

32. RESISTANCE WINDINGS AT 75 C˚
Where :
T: CONSTANT == for copper
T1: 75C˚
T2: The temperature at which the measurement (19C ˚).
Rt1: Resistance value at the temperature (75C ˚).
Rt2: Resistance value at measured temperature
Rt1= ohm
TESTING AND MAINTENANCE OF POWER TRANSFORMER

33. A V V V 1-3-Measurement of winding resistance
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
VOLTMETER – AMMETER
Apply ohm law
H.V N B C
D.C
12V V A N B
M.V C A V
L.V C B
TESTING AND MAINTENANCE OF POWER TRANSFORMER

34. 1-3-Measurement of winding resistance
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
WINDING REST. H.V
The use of modern equipment a N b c C B A
L.V
H.V
M.V n
TR. 2 1
The use of modern equipment
TESTING AND MAINTENANCE OF POWER TRANSFORMER

35. 1-3-Measurement of winding resistance
What is the benefit of?
1- It is to compare the design calculations in terms of volumes conductors used
2- Resistance winding test used in calculating copper losses
TESTING AND MAINTENANCE OF POWER TRANSFORMER

36. S.C ON L.V 1-4-IMPEDANCE VOLTAGE TEST(Z) A A A
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
VOLTMETER - AMMETER
S.C ON L.V A A A
TESTING AND MAINTENANCE OF POWER TRANSFORMER

37. IMPEDANCE VOLTAGE TEST(Z)
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
IMPEDANCE VOLTAGE (Z) :( H.V—L.V) (1,9,17) TAP POS.
IMPEDANCE VOLTAGE (Z) :( H.V—M.V) (1,9,17) TAP POS.
Tap pos.
A-B
B-C
C-A A B C 1
420V
422V
429V
3.5AMP
3.3AMP
3.4AMP 9 17
TESTING AND MAINTENANCE OF POWER TRANSFORMER

38. Why do we apply the equation below?
IMPEDANCE VOLTAGE TEST(Z)
Why do we apply the equation below?
FOR EXAMPLE:
Rated voltage =145.2kv , Rated current =250.5
Applied voltage Measured current
AB= A=3.5
BC= B=3.3
CA= C=3.4
Apply the law :
Z=+ -7.5% FOR TWO WINDINGS
Z=+ - 10%FOR THREE WINDINGS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

39. IMPEDANCE VOLTAGE TEST(Z)
What is the benefit of?
1- In the case of connecting a power transformer in parallel with the other
Test engineer must calculate the value of impedance. A impedance value should be close.
2- When measuring three windings currents, they are roughly equal. In the case of a damage in one winding .the current size. it will be bigger than two windings remaining. This gives an indication of the presence of a defect in winding.
3- Read the short circuit level
FOR EXAMPLE:
Rated voltage =145.2kv , Rated current =250.5
TESTING AND MAINTENANCE OF POWER TRANSFORMER

40. 1-5-Dielectrics Test
The dielectrics are separation between the parts of the electrical system, and it may be solid or gaseous or liquid or free space , and there is no insulating material full electrical insulation , there is a certain electric current passes through it , in spite of the low value of the electric current .You should know the value of this electric current.
The dielectric value less over a period of time. Because of their exposure to different pressures
TESTING AND MAINTENANCE OF POWER TRANSFORMER

41. 1-5-Dielectrics Test Types of dielectric tests
1- Measurement of insulation resistance
2- Dissipation power factor / insulation power factor (tan∂)
3- Test oil
TESTING AND MAINTENANCE OF POWER TRANSFORMER

42. 1-5-1- Measurement of insulation resistance.
1- Measures the insulation resistance of HV & LV windings with respect to earth (body) and between LV & HV winding.
2- Voltage used: 1000 V to 5000 V
3- Recommended Values are ( M)Ohms for HV & 500 Mohms for LV.
4- Equipment used: MEGGER IS USED.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

43. 1-5-1- Measurement of insulation resistance.
Type: 132/33 /11.5KV ,63 MVA
VECT. GROUP: YnYn0d11
insulation resistance :( H.V—L.V) a N b c C B A
L.V 11.5kv
H.V 132kv
M.V33kv n
TR.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

44. 1-5-1- Measurement of insulation resistance.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

45. 1-5-2-Dissipation power factor
this test done on the electrical transformer to see the quality of isolators used in the TRANSFORMER WINDINGS . and isolators operate among themselves capacitors as in the illustration.
132 kv
33 kv
11.5 kv
TESTING AND MAINTENANCE OF POWER TRANSFORMER

46. 1-5-2-Dissipation power factor
1- In capacitor ideal has no losses. The electric current precedes voltage an angle of (90˚).
TESTING AND MAINTENANCE OF POWER TRANSFORMER

47. 1-5-2-Dissipation power factor
2- In practical, all capacitors find where the loss in insulation
TESTING AND MAINTENANCE OF POWER TRANSFORMER

48. 1-5-2-Dissipation power factor
TESTING AND MAINTENANCE OF POWER TRANSFORMER

49. 1-5-2-Dissipation power factor
TESTING AND MAINTENANCE OF POWER TRANSFORMER

50. 1-5-2-Dissipation power factorb c C B A
L.V 11.5kv
H.V 132kv
M.V33kv n
TR.
Tan
TESTING e
REPEAT THIS TEST:
M-HLE: MEDIUM – HIGH , LOW , EARTH
L-HME : LOW – HIGH , MEDIUM , EARTH
H-M / H-L / M-L /
TESTING AND MAINTENANCE OF POWER TRANSFORMER

51. 1-5-2-Dissipation power factor
To find good values
TESTING AND MAINTENANCE OF POWER TRANSFORMER

52. 1-5-3- OIL TEST 1- Oil breakdown voltage is checked as per IS-335.
100 mm L X 70 mm B X 80 mm Ht. glass pot.
500ml Oil sample.
2- Spherical electrodes with gap of 2.5 mm
3- Recommended value : 60KV
4- Equipment used : OIL BDV TEST SET.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

53. DEFINITION OF THE TRANSFORMER
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
TESTING AND MAINTENANCE OF POWER TRANSFORMER

54. Regular maintenance for power transformers
1- Periodic checking of any loose connections of the terminations of HV & LV side.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

55. Regular maintenance for power transformers
2-Breather examination. Dehydration of Silica gel if necessary.
3-Explosion vent diaphragm examination.
4-Conservator to be cleaned from inside after every three years.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

56. Regular maintenance for power transformers
5- Regular inspection of OIL & WINDING TEMPERATURE METER readings.
6- Cleanliness in the Substation yard with all nets, vines, shrubs removed.
TESTING AND MAINTENANCE OF POWER TRANSFORMER

57. TESTING AND MAINTENANCE OF POWER TRANSFORMER
University of Turkish Aeronautical Association
Faculty of engineering EEE department
TESTING AND MAINTENANCE OF POWER TRANSFORMER
Thank you for your attention!
Questions?
TESTING AND MAINTENANCE OF POWER TRANSFORMER