INSPECTION PROCEDURE FOR UNIT TRANSFORMER.pdf

7/28/2019 INSPECTION PROCEDURE FOR UNIT TRANSFORMER.pdf

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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 FOR REVIEW REFLECT COMMENT M.S.SEO T.W.KIM T.M.KWON

C 19th

MAR 12 FOR REVIEW

Revised Lightning

Impulse Test acceptance

criteria

M.S.SEO T.W.KIM T.M.KWON

B 12th,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

OWNERS ENGINEER

MAIN CONTRACTOR

SUB CONTRACTOR


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RABIGH POWERPLANT No.2

Inspection Procedure for Unit TransformerDoc.No Z-RPP2-WE-001308

Page 2 of 13 Rev 0

Table of Content

1. Unit Transformer Test Procedure 3~ 10(Ref. Hyundai Inspection and Test Procedure II Page 6 ~ Page 13)

2. SEC recommendation method 11~12

3. Addenda for type and routine test 13


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No. INSPECTION & TEST ITEMS DESCRIPTION PASS / ACCEPTANCE CRITERIA

7 Insulation power factor and capacitance 1. Capacitance C1 and tan delta of condenser bushings in

measurement of capacitor bushing(Ro) 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

8 No-load loss & current measurement(Ro) 1. The test shall be made at 70%, 90%,100%,110% & 120% of * No-load loss & excitation current

Before and after dielectric tests rated voltage and rated frequency.(60Hz) Tap pos. : rated tap No-load loss Excit. Current(%)

2. The test voltage shall be applied to a LV winding with 70%

the other winding left open circuited. 100%

3. The loss will be measured by three wattmeter method. 110%

4. After the completion of the dielectric test the excitation 120%losses shall be measured at 100% rated voltage. * Tolerance of excitation current : +30%

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 voltageand excitation losses measurements repeated.

(Measurement of harmonic contents)(S) 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.

9 Sound level measurement(S) 1. The transformer shall be energized at rated voltage * Sound Pressure level

and frequency with no load. 76 dB(A) at ONAN base,0.3meter 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 shallbe measured at factory.

4. The background noise level before and after test shall be

measured.

Inspection Procedure for Unit Transformer

- -

RABIGH POWER PLANT No.2

79KW 0.24%

120KW 2.40%

120KW 2.40%


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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

12. Impulse tests(Ro) 1. The test will be made according to IEC:60076-3, clause 13,14 * To be withstood

(Just after temp. rise test, hot condition) if not specified in this procedure.

Lightning impulse test 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

Dielectric test sequence Neutral : R.FW - FW - FW - FWWhere R.FW is the reduced full wave, FW is full wave,

lightning impulse--> neutral lightning --> R.CW is reduced chopped wave, CW is chopped wave.

separate source AC -->ACSD--> 5. Standard voltage wave form(Front/Tail time)

ACLD--> capacitance&tan delta Full wave : 1.230% / 5020%

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 : 250kV2) LV1 and LV2 winding : 125kV

3) LV Neutral : 125kV




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13 Separate-source AC voltage withstand 1. Test voltage at rated frequency must be adjusted using * To be withstood

test(Ro) 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 to earth : 95kV2) LV1 winding and neutral to earth : 50kV

3) LV2 winding and neutral to earth : 50kV

14 Induced overvoltage withstand test(Ro) 1. The transformer shall be excited with high frequency power * To be withstood

source to prevent from saturation of magnetizing flux.

2. Test frequency : 180Hz or 240Hz

3. Test duration : 60Sec

4. Test voltage : 50KV at HV (Two times of Um)

15 Zero-sequence impedance 1. The test shall be made at rated frequency between

measurement(S) 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 220380V 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 * Not to be abnormal condition

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




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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.

18 Oil leakage and pressure test(Ro) 1. Completely assembled transformer shall be subjected to * No leakage is allowed.

(In-process stage test before FAT) a pressure corresponding to twice the normal head of oil or

the normal oil column + 0.5kg/cm2 whichever is higher, for * Tank permanent Deformation : 1mm

12hrs. There shall be no leak or sweating by visual.

2. The transformer tank, conservator, coolers shall be subjected

to a pressure.

19 Control panel & Auxiliary equipment 1. Sequence test shall be performed according to approved * The inspection results shall be satisfied

check(Ro) drawings. with approved specification and 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). Routine tests with IEC 60044-1 and test

temperature indicators, fans and others shall be subjected to report shall be submitted.

an operational test to assure the proper coordinated functioning. 1. Polarity test

2. Insulation resistance

20 Bushing C.T test(Ro) 1. Ratio and polarity test of BCT shall be carried out 3. Powerfrequency test

before installation on transformer. 4. Inter-turn overvoltage test

2. Ratio error shall be measured between primary 5. current error and phase displacement

and secondary winding with BCT test system. 6. secondary winding resistance3. Polarity test shall be made by inductive kick




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No. INSPECTION & TEST ITEMS DESCRIPTION PASS / ACCEPTANCE CRITERIA7. Short circuit tests

X1-X2-X3 shorted together ; H1-H2, H2-H3, H3-H1

Y1-Y2-Y3 shorted together ;

H1-H2, H2-H3, H3-H1, X1-X0, X2-X0, X3-X0

26 Measurement of single phase low 1.Short circuit impedance per phase basis, between each pair

voltage impedance, 60Hz(Ro) of winding from the HV as well as LV, LV1 & LV2 side.

Measurement shall be performed for all tappings position at

HV - LV1, HV - LV2, HV - LV1+LV2 conditions.2. Test voltage : 380V5000V, 60HZ

27 Measurement of single phase excitation Single phase low voltage 220380V, 60Hz shall be applied

current at low voltage 60Hz(Ro) to each phase of HV, LV terminal by turn and the magnetizing

current is measured at max. volt. tap position.

(after core demagnetizing)

28 Tests on Bushing(Ro) Tests on bushings will be carried out at bushing manufacturer.

The test reports will be submitted for review.

29 Measurement of transient vol tage This test wil l be carried out after core and coil assembly but

transfer characteristic(S) before in-tanking. The type of instruments and combination of

tests, will be submitted for approval.

According to SEC recommended method(refer to the

attached SFRA)

Ro : Routine test Type & special test to be carried out on one unit only of the

T : Type test same type.

S : Special test Routine test to be carried out for all units.




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(Tap No. : 1/11/-, Frequency : 10Hz ~ 2MHz)

No. connection 1 11 1 11

1

2

3

4

5

6

7

8

9

10

1112

13

14

15

16

17

18

19

20

21

22

23

24

SEC MVA Sweep Frequency Response Analysis test table

Phase

1U-1N

open1V-1N

1W-1N



At tachment - SFRA

1U-2U (1N, 2V : Ground)

Inductive

Inter

winding

1V-2V (1N, 2W : Ground)1W-2W (1N, 2U : Ground)

1U-3U (1N, 3V : Ground)

1V-3V (1N, 3W : Ground)

1W-3W (1N, 3U : Ground)

1U-2U

Inter

winding

1V-2V

1W-2W

1U-3U

1V-3V

1W-3W

1U-1N (2U-2V : Short)

Short

1V-1N (2V-2W : Short)

1W-1N (2W-2U : Short)

1U-1N (3U-3V : Short)

1V-1N (3V-3W : Short)

1W-1N (3W-3U : Short)

1U-1N (2U-2V, 3U-3V : Short)

1V-1N (2V-2W, 3V-3W : Short)

1W-1N (2W-2U, 3W-3U : Short)


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This test wi ll be carr ied out at A, B and C ph asewith same method.


Inspection Procedure for Unit TransformerAt tachment -Transient Vol tage Test

MEASUREMENT OF TRANSIENT VOLTAGE TRANSFER CHARACTERIST

2W 2V

CH2

2U

CH5CH6

CH7CH3CH4

2W 2V

C

CH2

2U

CH5

CH6

CH7

CCH3C CH4

Fig. 1 The LV terminals are open

Fig. 2 Each LV terminals si earthed through a CF capacitor

1V

(+ Polarity)

1W

1U

CH1

1V

(+ Polarity)

1W

1U

CH1


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Type Test Temperature rise test(T) (Including over-load test)

Special Test Sound level measurement(S)

Measurement of transient voltage transfer characteristic.(S) - In-process test

Zero-sequence impedance measurement(S)

Vibration test(S)

Routine Test Visual inspection(Ro)

Winding resistance measurement(Ro)

Ratio check(Ro)

Phase relationship check(Ro)

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

Insulation power factor and capacitance measurement of transformer (Ro)

Insulation power factor and capacitance measurement of capacitance bushings (Ro)

No-load loss & current measurement(Ro) (Including harmonics measurement(S))

Impedance voltage and load loss measurement(Ro)

Lightning impulse test(Ro)

Separate-source voltage withstand test(Ro)

Induced overvoltage withstand test(Ro)

Magnetic balance test(Ro)

Test of on-load tap changer(Ro)

Oil leakage and pressure test(Ro) - In-process test

Control panel & Auxiliary equipment check(Ro)

Bushing C.T test(Ro)

Dissolved gas-in-oil analysis(Ro)

Vacuum test(Ro) - In-process test

Mineral insulation oil test(Ro)

SFRA test(Ro)

Measurement of single phase low voltage impedance(Ro)

Measurement of single phase excitation current(Ro)

Tests on bushings(Ro)

Inspection Process Applicable Code


Inspection Procedure for Unit Transformeraddenda for type and routine test

IEC 60076-1(2000) Clause 10.5

IEC 60076-1(2000)

IEC 60076-3(2000) Clause 13.14

IEC 60076-3(2000) Clause 11

IEC 60076-3(2000) Clause 12

IEC 60076-2(2000)

IEC 551(1987)

MFR Standard

IEC 60076-1(2000) Clause 10.7

MFR Standard

Approved drawings

IEC 60076-1(2000) Clause 10.2

IEC 60076-1(2000) Clause 10.3

IEC 60076-1(2000) Clause 10.3

IEEE C57.12.90, 2006 CL 10.11

IEC 60076-1(2000) Clause 10.1.3,i)

IEC 60076-1(2000) Clause 10.1.3,i)

MFR Standard

IEC 137

IEC 44-1(1996)

MFR Standard

IEC 60296 (2003)

MFR Standard

MFR Standard

MFR Standard

IEC 60076-1(2000) Clause 10.8

MFR Standard

Approved drawings

IEC 44-1(1996)

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