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1
T E S T I N G A N D M A I N T E N A N C E O F P O W E R
T R A N S F O R M E RPresented by
Othman Al DarrajiDepartment of Electrical
EngineeringTAA. UniversityAnkara , Turkey
otomn_kh@yahoo.com
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
SupervisionProf. Dr. Ibrahim
MahariqDepartment of Electrical
EngineeringTAA. UniversityAnkara , Turkey
ibmahariq@gmail.com
Turkey – Ankara 10 - 5 - 2016
University of Turkish Aeronautical Association Faculty of engineering EEE department
Presented byOmar Saadi Alshear
Department of Electrical Engineering
TAA. UniversityAnkara , Turkey
omarsaad529@gmail.com
2T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
3
Transformer is a static device which transforms A.C electrical power from one voltage to anotherVoltage keeping The frequency same by Electromagnetic induction.
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
WHAT IS TRANSFORMER?
4T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
IRON CORE
WHAT IS TRANSFORMER?
5T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
6
1- NAME PLATE FOR TRANSFORMER
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
S.N: 925 554
1 = 5 0 K V A2 = 1 0 0 K V A3 = 2 0 0 K V A4 = 3 0 0 K V A5 = 5 0 0 K V A6 = 8 0 0 K V A7 = 1 0 0 0 K V A8 = 1 5 0 0 K V A
TEST REQUIREMENTS
7T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
2-TESTING DEVICES
TEST REQUIREMENTS
8
3- SAFETY EQUIPMENT
4 - MECHANICAL EQUIPMENT
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
TEST REQUIREMENTS
9T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
10T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
TESTING OF TRANSFORMER
Types of testing
1- Routine tests
2- Type tests
3- Special tests
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1-ROUTINE TESTS
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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 TestA-Measurement of insulation resistance.
B- Dissipation power factor / insulation power factor (tan∂)
C- OIL TEST
TESTING OF TRANSFORMER
12
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.
2- TYPE TESTS
TESTING OF TRANSFORMER
13
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.
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
3-SPECIAL TESTS
TESTING OF TRANSFORMER
14T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
15T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Transformer Breakdowns
16T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Sources of faults in transformer
17T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
18T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Apply Tests Routine on Power Transformer
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYnd11
1-ROUTINE TESTS
19
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
6- Equipment used : Transformer Turns Ratiometer ( T T R)
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)
1-1-Measurement of voltage ratio
20T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11Rated ratio (Ynd11)H.V-L.V=( 132 / √3 ) / 11.5=6.6227 FOR TAP (9)
Tap pos. TAP Voltage(kv)
(A-N) / (a-c)(Measured
value)
(B-N) / (b-a)(Measured
value)
(C-N) / (c-b)(Measured
value)
Rated Ratio(Rated value )
1 145.2 / 11.5
91011
132.0 (132 ⁄ √3) ⁄ 11.5 = 6.627
17 118.8
1-1-Measurement of voltage ratio
21T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
TEST:
TR.
1-1-Measurement of voltage ratio
a
N
VECT. GROUP: Ynd11 FOR H.V – L.V
b
c CBA
L.V
H.V
M.V
Ratio meter
ac
b
n
a
TR.
N
22
The no-load deviation of the turn ratios should be ≤ % 0,5
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
APPLLY THIS LAW
1-1-Measurement of voltage ratio
23
.
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
The use of modern equipment
1-1-Measurement of voltage ratio
TTR (Transformer Turns Ratio)
24
This test is very important for an engineer to figure out directional connectivity for transformers.
(( Dy11 ,Yd11, Dy1,Yd1))
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1-2-Vector Group Verification
25T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Dy11
Yd11
26T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Yd1
Dy1
27T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Steps to implement the test
1-2-Vector Group Verification
STEP 2S.C
STEP 3Take V
B-b , B-c ,C-b , C-c
STEP 1Connect H.V
28T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Dy11
Yd11
Dy1
Yd1
Dd0
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
Yy0
29T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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.
1-3-Measurement of winding resistance
D.C RESISTANCE
30T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Tap pos. A-Nohm
B-Nohm
C-Nohm
Resistance 3-ph
Oil Temp Rest. At 75C˚
1
9 0.4108 0.4104 0.4192 1.2305 19C˚ 1.5023
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Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11 FOR H.V, USES TAP POS. 1-9-17FOR M.V , USES TAP POS. 1 - 3 - 5FOR L.V , USES TAP POS. 1
1-3-Measurement of winding resistance
31T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11WHEATSTON BRIDGE
a
N
WIND. REST. FOR H.V
b
c CBA
L.V
H.V
M.V
WHEATSTON BRIDGE
a
cb
na
TR.
N
1-3-Measurement of winding resistance
32T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Where :T: CONSTANT ==234.5. for copperT1: 75C˚T2: The temperature at which the measurement (19C ˚).Rt1: Resistance value at the temperature (75C ˚).Rt2: Resistance value at measured temperature
Rt1=1.502326 ohm
RESISTANCE WINDINGS AT 75 C˚
33T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11VOLTMETER – AMMETERApply ohm law D.C
12V
A
A
A
C
B
C
B
BC
N
N
AH.V
M.V
L.V
1-3-Measurement of winding resistance
V
V
V
34T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11WINDING REST. H.V
The use of modern equipment
a
N
bc CBA
L.V
H.V
M.Va
cb
na
TR.
N
2
1
1-3-Measurement of winding resistance
The use of modern equipment
35T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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
1-3-Measurement of winding resistance
36T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
S.C ON
L.VA A
A
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11VOLTMETER - AMMETER
1-4-IMPEDANCE VOLTAGE TEST(Z)
37T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Tap pos. A-B B-C C-A A B C
1 420V 422V 429V 3.5AMP 3.3AMP 3.4AMP
9
17
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11IMPEDANCE VOLTAGE (Z) :( H.V—L.V) (1,9,17) TAP POS.IMPEDANCE VOLTAGE (Z) :( H.V—M.V) (1,9,17) TAP POS.
IMPEDANCE VOLTAGE TEST(Z)
38T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Why do we apply the equation below?
Z=+ -7.5% FOR TWO WINDINGSZ=+ - 10%FOR THREE WINDINGS
FOR EXAMPLE:Rated voltage =145.2kv , Rated current =250.5Applied voltage Measured current AB=420 A=3.5 BC=422 B=3.3 CA=429 C=3.4 Apply the law :
IMPEDANCE VOLTAGE TEST(Z)
39
What is the benefit of?
1- In the case of connecting a power transformer in parallel with the otherTest 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 levelFOR EXAMPLE:Rated voltage =145.2kv , Rated current =250.5
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
IMPEDANCE VOLTAGE TEST(Z)
40
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
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1-5-Dielectrics Test
41T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Types of dielectric tests
1- Measurement of insulation resistance
2- Dissipation power factor / insulation power factor (tan∂)
3- Test oil
1-5-Dielectrics Test
42T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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.
1-5-1- Measurement of insulation resistance.
43T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
Type: 132/33 /11.5KV ,63 MVAVECT. GROUP: YnYn0d11insulation resistance :( H.V—L.V)
a
N
b
c CBAL.V 11.5kv
H.V 132kv
M.V33kv
a
cb
na
TR.
N
1-5-1- Measurement of insulation resistance.
44T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1-5-1- Measurement of insulation resistance.
45T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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.
1-5-2-Dissipation power factor
132 kv
33 kv
11.5 kv
46T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1- In capacitor ideal has no losses. The electric current precedes voltage an angle of (90˚).
1-5-2-Dissipation power factor
47T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
2- In practical, all capacitors find where the loss in insulation
1-5-2-Dissipation power factor
48T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1-5-2-Dissipation power factor
49T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1-5-2-Dissipation power factor
50T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
TESTING
REPEAT THIS TEST: M-HLE: MEDIUM – HIGH , LOW , EARTHL-HME : LOW – HIGH , MEDIUM , EARTHH-M / H-L / M-L /
a
N
b
c CBAL.V 11.5kv
H.V 132kv
M.V33kv
a
cb
na
TR.
N
Tan
1-5-2-Dissipation power factor
e
51T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1-5-2-Dissipation power factor
To find good values
52T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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 mm3- Recommended value : 60KV 4- Equipment used : OIL BDV TEST SET.
1-5-3- OIL TEST
53T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
DISCUSSION
DEFINITION OF THE TRANSFORMER
TEST REQUIRMENTS
TESTING OF TRANSFORMER
ROUTINE TESTS
REGULAR MAINTENANCE FOR POWER TRANSFORMERS
54T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
1- Periodic checking of any loose connections of the terminations of HV & LV side.
Regular maintenance for power transformers
55T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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.
Regular maintenance for power transformers
56T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
5- Regular inspection of OIL & WINDING TEMPERATURE METER readings.
6- Cleanliness in the Substation yard with all nets, vines, shrubs removed.
Regular maintenance for power transformers
57
Thank you for your attention!
Questions?
TESTING AND MAINTENANCE OF POWER TRANSFORMER
University of Turkish Aeronautical Association
Faculty of engineering EEE department
T E S T I N G A N D M A I N T E N A N C E O F P O W E R T R A N S F O R M E R
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