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 ibmahariq@gmail.com Presented by Othman Al Darraji Department of Electrical Engineering TAA. University Ankara , Turkey otomn_kh@yahoo.com Presented by Omar Saadi Alshear Department of Electrical Engineering TAA. University Ankara , Turkey omarsaad529@gmail.com Turkey – Ankara 10 - 5 - 2016 TESTING AND MAINTENANCE OF POWER TRANSFORMER

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

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

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

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

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

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

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

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

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

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

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.

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

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

Transformer Breakdowns TESTING AND MAINTENANCE OF POWER TRANSFORMER

Sources of faults in transformer TESTING AND MAINTENANCE OF POWER TRANSFORMER

TESTING AND MAINTENANCE OF POWER TRANSFORMER

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

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

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=6.6227 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

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

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

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

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

Dy11 Yd11 TESTING AND MAINTENANCE OF POWER TRANSFORMER

Dy1 Yd1 TESTING AND MAINTENANCE OF POWER TRANSFORMER

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

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

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

1-3-Measurement of winding resistance Type: 132/33 /11.5KV ,63 MVA VECT. GROUP: YnYn0d11 FOR H.V, USES TAP POS. 1-9-17 FOR M.V , USES TAP POS. 1-3 -5 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

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

RESISTANCE WINDINGS AT 75 C˚ Where : T: CONSTANT ==234.5. 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=1.502326 ohm TESTING AND MAINTENANCE OF POWER TRANSFORMER

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

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

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

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

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

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=420 A=3.5 BC=422 B=3.3 CA=429 C=3.4 Apply the law : Z=+ -7.5% FOR TWO WINDINGS Z=+ - 10%FOR THREE WINDINGS TESTING AND MAINTENANCE OF POWER TRANSFORMER

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

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

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

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

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

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

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

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

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

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

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

1-5-2-Dissipation power factor b 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

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

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

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

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

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

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

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