INSPECTION PROCEDURE FOR STATION TRANSFORMER.pdf

0

21,NOV,’12

FOR CONSTRUCTION

FOR CONSTRUCTION

S.Y.KIM

T.W.KIM

T.M.KWON

E

06,NOV,’12

FOR REVIEW

REFLECT COMMENT

S.Y.KIM

T.W.KIM

T.M.KWON

D

14 ,May,’12

th

FOR REVIEW

REFLECT COMMENT

M.S.SEO

T.W.KIM

T.M.KWON

C

19 MAR 12

th

FOR REVIEW

Impulse Test acceptance

M.S.SEO

T.W.KIM

T.M.KWON

Revised Lightning criteria th

B

12 ,JAN,’12

FOR REVIEW

REFLECT COMMENT

M.S.SEO

T.W.KIM

T.M.KWON

REV.

DATE

STATUS

DESCRIPTION

PREPARED BY

CHECKED BY

APPROVED BY

Owner

RABIGH POWER PLANT NO.2 PROJECT UNITS # 01, 02, 03 & 04 Contract # 31021001/00 OWNER’S ENGINEER

MAIN CONTRACTOR

SUB CONTRACTOR

DOCUMENT TITLE

Inspection Procedure for Station Transformer (Reference document : HHI-ITP-11-104 page 6 ~ 16)

NAME

DATE

PREPARED BY

S.Y.KIM

21, NOV,’12

CHECKED BY

T.W.KIM

21, NOV,’12

APPROVED BY

T.M.KWON

21, NOV,’12

DOCUMENT NO.

Approval/Certification Information

31021001/00-Z-RPP2-WE001307

Doc No.: PB-10195 Rev.: v1

No. of Pages 16

DOCUMENT STATUS:

□ FOR INFORMATION □ FOR APPROVAL □ FOR REVIEW ■ FOR CONSTRUCTION □ AS BUILT

Rev. No. 0

RABIGH POWER PLANT No.2 Inspection Procedure for Station Transformer

Doc.No Page

Z-RPP2-WE-001307 2 of 16

Rev

Table of Content

1. Station Transformer Test Procedure

3 ~ 13

(Ref. Hyundai Inspection and Test Procedure II Page 6 ~ Page 16)

2. SEC recommendation method

14~ 15

3. Addenda for type and routine test

16

0

RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No. 1.

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INSPECTION & TEST ITEMS Visual inspection(Ro)

DESCRIPTION 1. Construction, painting & welding condition will be inspected visually. 2. Dimension will be measured in accordance with the approved specification.

PASS / ACCEPTANCE CRITERIA * The inspection results shall be satisfied with approved specification and drawings.

2.

Winding resistance measurement(Ro)

1. The winding resistance will be measured by the DC voltage drop method with resistance measuring system. 2. This test shall be made on all windings and all tap positions. 3. Test results shall be corrected to 75℃ values. 4. This test shall be repeated at the end of tests. 5. DC current : Max. 100A

3.

Ratio check(Ro)

1. The voltage ratio shall be measured by means of transformer turns ratio(TTR) test set and on single phase, phase by phase. 2. The applied voltage to HV winding will be about 120(V). 3. The test shall be made on all windings and all tap positions.

* Ratio error shall be within ±0.5% at all tappings.

4.

Phase relationship check(Ro)

1. The phase relationship shall be checked at rated voltage tap connection. 2. Three phase 220(V) will be applied to HV winding and the voltage shall be measured between terminals. 3. Vector diagram will be drawn and confirmed.

* Phase relationship YNyn0yn0(d1)

5.

Insulation resistance measurement(Ro) (Including core insulation test)

1. The test shall be made between HV and LV1 winding, HV and LV2 winding, LV1and LV2 winding, HV winding and earth, LV1winding and earth, LV2 winding and earth with 5000(V) megger tester. 2. The test shall be made on 15Sec,1min. and 10 minutes. 3. Core to earth, clamp to earth, core+clamp to earth for one minute with 3500V megger.

* PI : Min. 1.3

6.

Insulation power factor and capacitance measurement(Ro) (Before and after dielectic tests)

1. The test shall be made each winding to ground and between the windings with Doble tester. 2. IEEE C57.12.90 table 4 method II is prefered. 3. Test voltage shall be from 2kV to 12kV in steps of 2kV.

* P.F : max. 0.5% at 20 ℃

RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No. 7

8

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INSPECTION & TEST ITEMS Insulation power factor and capacitance measurement of capacitor bushing(Ro)

DESCRIPTION 1. Capacitance C1 and tan delta of condenser bushings in voltage range of 0 to 12kV in step of 2kV shall be measured on each capacitor bushings. 2. The bushings with tan delta > 0.4% at < 30℃ shall be rejected. 3. Capacitance C2 and tan delta shall be measured at 0.5 & 1.0 Kv. 4. The tests on bushings shall be performed separately from transformer. C1: 10kV, C2: 0.5kV

No-load loss & current measurement (Ro) This test shall be performed before and after dielectric test

1. The test shall be made at 70%, 90%,100%,110% & 120% of rated voltage and rated frequency.(60Hz) Tap pos. : rated tap 2. The test voltage shall be applied to a LV winding with the other winding left open circuited. 3. The loss will be measured by three wattmeter method. 4. After the completion of the dielectric test the excitation losses shall be measured at 100% rated voltage. The excitation voltage shall then be increased to 110% rated voltage and the transformer left excited for 1 hour. The voltage shall then be reduced to 100% of rated voltage and excitation losses measurements repeated. 5. Measurement of harmonics of no-load current at 100%, 110% and 120% rated voltage. 6. 1,2,3,5,7,9,11th and 13th harmonic content shall be measured using harmonic analyzer and expressed as percentage of 60Hz component.

* No-load loss & excitation current No-load loss Excit. Current(A) 70% 90KW 4.1 at LV 100% 14.8 at LV 128KW 110% 190KW 120% * Tolerance of excitation current : +30%

1. The transformer shall be energized at rated voltage and frequency with no load. 2. The microphone shall be located at 1mt interval and spaced 0.3m(ONAN base) from datum level. 3. The frequency spectra of the audible sound pressure shall be measured at factory. 4. The background noise level before and after test shall be measured.

* Sound Pressure level 76 dB(A) at ONAN base,0.3meter

(Measurement of harmonic contents)(S)

9

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Sound level measurement(S)

PASS / ACCEPTANCE CRITERIA

RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No. 10

11

INSPECTION & TEST ITEMS Impedance voltage & load-loss measurement(Ro)

Temperature rise test(T) (Before dielectric tests)

DESCRIPTION 1. The test shall be made at rated frequency and current by short circuit method. 2. The test shall be made on the principal, highest and lowest voltage tap positions at 1.0Pu, 1.1Pu and 1.3Pu load current base on Max. rating( HV-LV1, HV-LV2). But the test of LV1-LV2 will be carried out at low capacity and the rusults will be corrected to 1.0PU and 1.3PU. The test to be performed at all other taps at 0.5Pu.( HV-LV1 & HV-LV2 ) 3. The load loss and impedance voltage will be measured on Max. rating base and corrected to the other ratings. 4. Symmetric loading(load balance) should be checked at extreme taps and principal tap base on Max. rating, and the results to be included at final test report. 5. The measured load loss and impedance voltage shall be corrected to the reference temperature of 75℃. 1. The test shall be made at the maximum loss tap with the rated frequency by short circuit method. 2. At first, to determine the top oil and the average oil temperature rise, the test losses shall be supplied as follow; Test losses ( Total loss ) = Load loss + No Load loss 3. After saturation, input shall be then reduced to rated current and this current is maintained for 1 hour. 4. After shut down the electric power, the temperature of winding is determined by the resistance method. Resistance measurement shall be made first on the highest temperature winding, then other windings. 5. The sequence of test shall be as follows (HV-LV1+LV2) ; a) 100% ONAN and 100% ONAN cooling without spare 110% ONAN and 100% ONAN cooling with spare cooler. b) 130% ONAN and 100% ONAN cooling without spare cooler for 4hours preceeding load of 1.0pu continues. 6. Thermograpic infra-red scanning of transformer tank walls,

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PASS / ACCEPTANCE CRITERIA * % imped. and load loss at 75℃, principal tap Load loss % Imp.(80MVA) 250KW HV-LV1, 80MVA HV-LV1:18.0% 250KW HV-LV2, 80MVA HV-LV2:18.0% 500KW HV-(LV1+LV2), 160MVA HV-(LV1+LV2) of %imp. (160MVA, 75℃) : 20% Tol of %imp. : +7.5% * refer to data sheet for other %imp values.

* Oil temperature rise : 40℃ * Winding temperature rise : 45℃ * Hot spot temperature rise : 48℃ At end of overload, The following hot spot temp. shall not be exceed. Base on Max. ambient temp. of 50℃. * Top oil temp. : 115℃ * Winding hot spot temp./metalic parts : lightning impulse--> neutral lightning --> separate source AC -->ACSD--> ACLD--> capacitance&tan delta

DESCRIPTION bushing turrets and covers shall be performed during over-load temperature rise test. 7. Following data shall be recorded/calculated; a) bushing stud temperatures at the end of over-load heat run. b) average oil time constant c) winding time constant 1. The test will be made according to IEC:60076-3, clause 13,14 if not specified in this procedure. 2. Polarity of test voltage : Positive 3. The test shall be carried out with OLTC on SW. POS. 1, 11 and 21 with each of the three phases being tested for LI. During neutral test, tap position should be minimum volt. 4. Test sequence HV, LV1, LV2 winding : R.FW-FW-R.CW-CW-CW-FW-FW Neutral : R.FW - FW - FW - FW Where R.FW is the reduced full wave, FW is full wave, R.CW is reduced chopped wave, CW is chopped wave. 5. Standard voltage wave form(Front/Tail time) Full wave : 1.2㎲±30% / 50㎲±20% Chopped wave : 2㎲ ∼ 6㎲ Neutral : front time up to 13㎲ 6. Impulse current traces, with a sweep time of 10 to 25us shall be recorded. 7. The required crest voltage for LI shall be increased if the actual front time exceeds 2.0us or the actual time to 50% crest value is less than 40us according to correction factor table in the SEC spec. 8. Recording shall be of minimum three independent channels for LI. 9. Test voltage(LI) 1) HV winding : 1425kV 2) LV1 and LV2 winding : 250kV 3) HV Neutral : 650kV

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PASS / ACCEPTANCE CRITERIA

* To be withstood

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RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No. 12.2

INSPECTION & TEST ITEMS Swiching impulse tests(Ro)

Doc :WE-001307

DESCRIPTION 1. The test will be made according to IEC:60076-3, clause 15 if not specified in this procedure. 2. Polarity of test voltage : Positive 3. The test shall be carried out with OLTC on SW. POS. 1, 11 and 21 with each of the three phases being tested for SI. 4. Test sequence. HV winding : R.FW - FW - FW - FW Where R.FW is the reduced full wave, FW is full wave. 5. Before a test, an overall check of the test circuit and measurement system shall be performed at a voltage lower than the reduced voltage level. 6. Test voltage(SIL) HV winding : 1050kV

PASS / ACCEPTANCE CRITERIA * To be withstood * According to SEC-GP-001-R2, cl 23.12.2

13

Separate-source AC voltage withstand test(Ro)

1. Test voltage at rated frequency must be adjusted using peak volt meter. 2. The single phase AC voltage shall be applied to each winding with other winding and tank solidly grounded. 3. Test frequency and duration : 60 Hz / 60sec 4. Test voltage 1) HV winding and neutral to earth : 275kV 2) LV1 winding to earth : 95kV 3) LV2 winding to earth : 95kV

* To be withstood

14

Induced overvoltage withstand test(Ro)

1. Before commencing test, calibration of votage potential dividers at two standard voltages levels shall be done. 2. The transformer shall be excited with high frequency power source to prevent from saturation of magnetizing flux. 3. Test frequency : 180Hz 4. Induced overvoltage withstand test shall be performed on each HV line to ground with other lines grounded as per IEC6076-3 Clause 12.4 5. Equipment for PD : 3channel for HV bushings On each HV line to earth with other lines grounded as follow; 1) Test connection

* To be withstood

14.1 a) Phase to earth test (ACSD)

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RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No.

INSPECTION & TEST ITEMS

DESCRIPTION

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PASS / ACCEPTANCE CRITERIA

HV Winding (U1) 420kV U1= 630kV 210kV

2) Test voltage(at HV) ; U1 = 630KV (Phase to ground ) U2 = 1.5Um/√3 = 364KV (Phase to ground ) U3 = 1.1Um/√3 = 267KV (Phase to ground ) (Um ; 420kV, Test tap : #1 ) 3) Test duration(ACSD) E(%) U1

* Partial discharge level shall not exceed 100(pC) at test voltage(U2).

60Sec

U2 U3

5 min 5min

5 min

5min

Time

The voltage shall be switched on at a level not high than one-third of U2, raised to U3, held there for a duration of 5min, raised to U2, held there for a duration of 5min, raised to U1, held there for a duration of 60sec, immediately reduced again

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RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No.

INSPECTION & TEST ITEMS

Doc :WE-001307

DESCRIPTION

Rev.0

PASS / ACCEPTANCE CRITERIA

without interruption to U2, held there for a duration of 5min, and reduced to U3, held there for 5min. And reduced 14.2

Phase to earth test (ACLD test)

a value below one-third of U2 before switch-off. On each HV line to earth with other lines grounded as follow; 1) Test connection

U1=485kV

4) Test duration(ACLD); E(%) U1

* Partial discharge level shall not exceed 100(pC) at test voltage(U2).

60sec

`

U2 U3

5 min 5min

ACLD :60 min

5min

Time

The voltage shall be switched on at a level not high than one-third of U2, raised to U3, held there for a duration of 5min, raised to U2, held there for a duration of 5min, raised to U1, held there for a duration of 60sec, immediately reduced again without interruption to U2, held there for a duration of 60min, and reduced to U3, held there for 5min. And reduced a value below one-third of U2 before switch-off.

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RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No.

INSPECTION & TEST ITEMS

Doc :WE-001307

DESCRIPTION 5) Test voltage(at HV) U1 = 2.0Um/√3 = 485kV(Phase to ground) U2 = 1.8Um/√3 = 437kV(Phase to ground) U3 = 1.1Um/√3 = 267kV(Phase to Ground)

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PASS / ACCEPTANCE CRITERIA

15

Zero-sequence impedance measurement(S)

1. The test shall be made at rated frequency between the line terminals and the neutral. 2. The zero sequence impedance shall be measured on the rated and extrem tap positions. 3. Sketch showing the magnetic core and the disposition of windings shall be enclosed with the report. 4. The measuring current must not be higher than 30% of the nominal current.

16

Magnetic balance test(Ro)

1. Single phase voltage 220…380V 60Hz be applied to each phase of HV or LV1 or LV2 line terminals by turn and voltage induced in the other phases are to be measured.

17

Test of on-load tap changer(Ro)

1. Operation test With the tap changer fully assembled on the transformer, following sequence of operations shall be performed without failure; a) with transformer un-energized, 8 complete cycles of operation at no load, 1 complete cycle of operation. b) with transformer un-energized, and with the auxiliary voltage reduced to 85% of its rated value, 1 complete cycle of operation. c) with transformer energized at rated voltage and frequency at no load, 1 complete cycle of operation. d) with one winding short-circuited and, as far as practicable, rated current in the tapped winding, 10 tap-change operations across the range of two steps on each side from where a coarse or reversing changeover selector operates, or otherwise from the middle tapping. 2. Power frequency withstand test shall be carried out on auxiliary devices with 2000V AC for 1 min.

* Not to be abnormal condition

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RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer No. 18

INSPECTION & TEST ITEMS Oil leakage and pressure test(Ro) (In-process stage test before FAT)

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DESCRIPTION 1. Completely assembled transformer shall be subjected to a pressure corresponding to twice the normal head of oil or the normal oil column + 0.5kg/cm2 whichever is higher, for 12hrs. There shall be no leak or sweating by visual. 2. The transformer tank, conservator, coolers shall be subjected to a pressure.

PASS / ACCEPTANCE CRITERIA * No leakage is allowed. * Tank permanent Deformation : ≤1mm

19

Control panel & Auxiliary equipment check(Ro)

1. Sequence test shall be performed according to approved drawings. 2. The voltage to ground shall be 2500Vrms for equipment rated up to 250Vdc and 1500Vrms for other voltage ratings. Test voltage across open contacts shall be 1500Vrms for contacts rated for tripping and 1000V for contact not rated for tripping.(for 1 minute with all the circuits tied together) 3. Insulation resistance shall be measured with 500(V) megger tester(Include C.T). temperature indicators, fans and others shall be subjected to an operational test to assure the proper coordinated functioning.

* The inspection results shall be satisfied with approved specification and drawings.

20

Bushing C.T test(Ro)

1. Ratio and polarity test of BCT shall be carried out before installation on transformer. 2. Ratio error shall be measured between primary and secondary winding with BCT test system. 3. Polarity test shall be made by inductive kick method with DC voltage source. 4. The magnetization tests of bushing C.T for protective relay shall be taken before assembly in the transformer tank and to be shown. 5. The C.T secondary winding resistance measurements shall be performed on with the bridge method.

Routine tests with IEC 60044-1 and test report shall be submitted. 1. Polarity test 2. Insulation resistance 3. Powerfrequency test 4. Inter-turn overvoltage test 5. current error and phase displacement 6. secondary winding resistance

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RABIGH POWER PLANT No.2

Inspection Procedure for Station Transformer DESCRIPTION Oil samples shall be taken before and after for gas-in-oil analysis as following stages; 1) All tests 2) 1 hr 110% excitation test. 3) Temperature rise test 4) Overload test 5) After 6…12hrs after shut down 6) After complete tests.

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No. 21

INSPECTION & TEST ITEMS Dissolved gas-in-oil analysis(Ro)

PASS / ACCEPTANCE CRITERIA

22

Vacuum test(Ro)(In-process stage before final acceptance test)

Certificate of vacuum test of the tank shall be submitted with final report. (Test duration : 6hrs) (Full vacuum, less than 1 torr for tank, cooler, conservator and tap changer)

* Tank permanent Deformation : ≤1mm

23

Mineral insulation oil test(Ro)

Before and after transformer tests, We will check dielectric strength, moisture content, particle contents(IEC 60970) in transformer oil.

* Review of test reports. Break down volt.(IEC 60156) : 70kV, Water content (IEC 60814) :