Doble Engineering - Testing Rectifier Transformers - Slides

Testing Rectifier-Transformers y n

pa m o C

ring e e ngin Pierre Leblanc, Alcoa Mt Holly E le b o D Simard, Rio Tinto Alcan ©Hugo

Long Pong, Doble Engineering

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Testing Rectifier-Transformer, March 2012

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Outline  Background and Motivations  Review Test Principles  Case Studies any p m Co Holy  Fuji Rectifier Transformer in g Alcoa-Mt n i r ee in RTA-Alma  ABB Rectifier Transformer n i g En  TTI Rectifier in RTA-Laterrière le Transformer b o D ©  CWC Rectifier Transformer in RTA-Arvida  Conclusion & Lessons Learned

Testing Rectifier-Transformer, March 2012

Rectifier Transformers - Vector Diagram 3-winding transformer

4 Case Studies: # 1

HV ∆

LV ∆∆

Case Study I. Alcoa-Mt Holy

Overall Excitation Ratio

2

Y

∆∆

3

Y

Y∆

4

YY

∆Y

5 6

∆Y ∆

E ∆ ∆ III. leRTA-Laterrière b o ©D IV. RTA-Arvida Y−Y Y−Y

7

Y

II. RTA-Alma



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

any p m Co  

 



Y−Y Y−Y Testing Rectifier-Transformer, March 2012

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Background & Motivation • Challenge: Short time for maintenance testing and disconnect the LV terminals from rectifier is major work. any with • Purposes: How to test a transformer p m Co valid test rectifier connected anderto ngobtain i e results for condition nginassessment of the E ble transformer ©Do insulation

Testing Rectifier-Transformer, March 2012

Field Challenge HV Side: Bushing

LV Side: Bus bars go through the building wall

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any p m Co

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Testing Rectifier-Transformer, March 2012

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Field Challenge • LV side: bus bars in the building come through wall from transformer • Surge capacitors (3-9uF) any p m to be disconnected Co g n i r during tests. inee

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le E b o ©D

LV Terminals

Testing Rectifier-Transformer, March 2012

Test Principle • Same as standard routine tests: – Overall – Bushing – Surge Arrestor – Exciting Current – Doble Ratio

any p m Co

ring e e in nghaving E • With Exception of rectifier connected ble o D © This affects only Overall test. at LV side.

Testing Rectifier-Transformer, March 2012

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Test Principle • Preparation: Isolate, short-circuit and ground both sides

ble ©Do

LV2

ring e e ngin

LV1

HV

ny

pa m o C

E

DC Bus Testing Rectifier-Transformer, March 2012

Test Principle

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eri e n i ng

any p m Co LV2

LV1

HV

• Preparation: Isolate, short-circuit and ground both sides

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DC Bus Testing Rectifier-Transformer, March 2012

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Test Principle • Preparation: Isolate, short-circuit and ground both sides

ble ©Do

LV2

ring e e ngin

LV1

HV

ny

pa m o C

E

DC Bus Testing Rectifier-Transformer, March 2012

Test Principle

any p m Co LV2

LV1

HV

• Preparation: Disconnect all surge capacitors

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DC Bus

Testing Rectifier-Transformer, March 2012

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Test Principle

ble ©Do

ring e e ngin

ny

pa m o C LV2

LV1

HV

• Preparation: Disconnect all surge capacitors

E

DC Bus

Testing Rectifier-Transformer, March 2012

Test Principle

any p m Co LV2

LV1

HV

• Preparation: Disconnect all surge capacitors

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DC Bus

Testing Rectifier-Transformer, March 2012

7

Test Principle

ble ©Do

LV2

ring e e ngin

ny

pa m o C LV1

HV

LV2

LV1

HV

• Two Configurations of Rectifier Circuit

E

Without DC bus interconnection

+

-

With DC bus interconnection in Red line

Testing Rectifier-Transformer, March 2012

Test Principle - Overall Test • Without DC side interconnection: – Tested as three-winding transformer all the time

• With DC side interconnection: – Tested as two-winding transformer; both LV any p windings are shorted together m o gC n – Tested as three-winding transformer in factory, i r e e n i commissioning orEdiagnostic ng

ble

©Do

Testing Rectifier-Transformer, March 2012

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LV2 LV2

LV1

E

HV

ble ©Do

HV

any p m Co LV1 winding: gTesting n i r ee (0.5kV, Lines 5, 6 & 7) n i g n

LV2

LV1

HV

Test connection as 3-winding: without DC bus interconnection

LV1

Test Principle - Overall Test

Testing HV winding: (Lines 1, 2 & 3) Testing LV2 winding: (0.5kV, Lines 9, 10 & 11)

Testing Rectifier-Transformer, March 2012

Test Principle - Overall Test

+

le- E b o ©D

Testing HV winding: (Lines 1, 2 & 3)

LV2

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eri e n i ng

any p m Co LV1

HV

LV2

LV1

HV

Test connection as 2-winding: with DC bus interconnection

+

-

Testing LV windings: (0.5kV, Lines 5, 6 & 7)

Testing Rectifier-Transformer, March 2012

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Case Study There are 4 case studies in the papers: 1. Fuji rectifier transformer (1979) at Alcoa plant in Mt-Holy, SC y aatnRTA p 2. ABB rectifier transformer (2010) m Co plant in Alma, QC ering e ngin 3. TTI rectifier transformer (1988) at RTA E le b o plant in Laterrière, QC ©D 4. CWC rectifier transformer (1941) at RTA plant in Arvida, QC

Testing Rectifier-Transformer, March 2012

1. Case Study-Fuji rectifier transformer at Alcoa Transformer Description:

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©Do

With DC interconnection in red line

Testing Rectifier-Transformer, March 2012

LV2

g

D/ D D eerin in EnFAg

any p m Co LV1

Fuji 1979 34.28 MVA 35.2/0.638; 0.638

HV

Manufacturer Year Capacity (MVA) Voltage (kV) HV/LV1; LV2 Configuration Class

+

-

10

1. Case Study-Fuji rectifier transformer at Alcoa

LV1

LV2

ble ©Do

ee n i g En

ny

pa m o C

HV

• Tested as 2-winding: – Without rectifier (factory), – With rectifier & surge capacitor – With rectifier & no surge capacitor • Tested as 3-winding as experimentation. ring

+

-

Testing Rectifier-Transformer, March 2012

1. Case Study-Fuji rectifier transformer at Alcoa Overall Test results as 2-winding Insulation

Without rectifier (Factory) %PF

CH+CHL

%PF

17,200

0.35

CH

8,450

0.53

CHL

8,750

0.28

CL+CHL

0.25

Cap (pF)

With Rectifier & With Surge Cap

0.23

CL CH+CL

0.18

0.36

17,155

ring e e 8,779 ngin

15,000 0.35 le E b o D © 6,250 0.35

CHL

Cap (pF) 8,376

With Rectifier & Rectifier Without Surge Cap Insulation %PF

Cap (pF)

ny a17,159 p m o 8,371 C0.53

Cap (pF)

0.33

0.13

8,786

5,971,794

1.94

23,385 8,385

5,962,622

2.93

14,609 8,359

8,774

0.13

8,784

15300

Testing Rectifier-Transformer, March 2012

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1. Case Study-Fuji rectifier transformer at Alcoa Overall Test results as 2-winding Insulation

Without rectifier (Factory) %PF

CH+CHL

0.25

CH CHL CL+CHL

0.23

Cap (pF)

0.36

8,450

0.53

17,155

With Rectifier & Rectifier Without Surge Cap Insulation

y Cap an(pF) p m o 17,159 C0.33 %PF

Cap (pF)

0.53

8,371

8,779

0.13

8,786

5,971,794

1.94

23,385 8,385

0.35

5,962,622

2.93

14,609 8,359

0.18

8,774

E 8,750 le 0.28 b o ©D15,000 0.35 15300

Cap (pF)

ring e e 8,376 ngin

0.35

CHL CH+CL

%PF

17,200

6,250

CL

With Rectifier & With Surge Cap

0.13

8,784

See only capacitor

Testing Rectifier-Transformer, March 2012

1. Case Study-Fuji rectifier transformer at Alcoa Overall Test results as 2-winding Insulation

Without rectifier (Factory) %PF

CH+CHL

%PF

17,200

0.35

CH

8,450

0.53

CHL

8,750

0.28

CL+CHL

0.25

Cap (pF)

With Rectifier & With Surge Cap

0.23

CL CH+CL

0.18

0.36

17,155

ring e e 8,779 ngin

15,000 0.35 le E b o D © 6,250 0.35

CHL

Cap (pF) 8,376

With Rectifier & Rectifier Without Surge Cap Insulation %PF

Cap (pF)

ny a17,159 p m o 8,371 C0.53

Cap (pF)

0.33

0.13

8,786

5,971,794

1.94

23,385 8,385

5,962,622

2.93

14,609 8,359

8,774

0.13

8,784

15300

See only LV winding (oil) < capacitor Rectifier (dry type) Testing Rectifier-Transformer, March 2012 Expect a higher CL %PF, because more dry type Insulation

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1. Case Study-Fuji rectifier transformer at Alcoa

pa m o C

ring + e e n i ng LV side = ? (Diode may conduct)

LV2

Testing Rectifier-Transformer, March 2012

LV2

-

LV1

E

HV

LV1

HV

+

LV2

ny

HV should be ok.

ble ©Do

LV1

HV

Can it be overall tested as 3-winding?

+

-

1. Case Study-Fuji rectifier transformer at Alcoa Can it be overall tested as 3-winding? Test results: kV %PF Cap (pF) Correlate to 2-winding test Insulation CH + CHL1 10 0.90 12,797 ≈ CH+CHL-CHL2 CH 10 0.72 8,380 ≈ CH in 2-winding CHL1 10 0.53 4,417 ≈ CHL/2 = (8,786 / 2) ny a p CL1 + CL12 0.049 2.78 12,274,610 Rectifier om conducting C g CL1 0.049 4.86 7,405 erin ≈ CL/2 = (14,609 / 2) e n i g CL12 0.049 2.06 Rectifier conducting En12,268,740 e l b o CL2 + CHL2 0.049 11,597 ≈ CL+CHL-CL1-CHL1 ©D 3.51 CL2 0.049 4.81 7,207 ≈ CL/2 = (14,609 / 2) CHL2 0.049 1.02 4,378 ≈ CHL/2 = (8,786 / 2) Test results correlate well to 2-winding test. Rectifier is Testing Rectifier-Transformer, March 2012 conducting at 50V, so test should be done as 2-winding.

13

1. Case Study-Fuji rectifier transformer at Alcoa Observations: • At the factory, the transformer should be tested as 3winding transformer • Surge capacitor need to be disconnected to n avoid y a p masking problem m Co g as n i • This transformer should be tested two-winding r e e n i when connected to this Engrectifier e l b • Other TestsD(bushing, surge and Exciting current) are © inothe same as standard test. performed

Testing Rectifier-Transformer, March 2012

Case Study- Rio Tinto Alcan (RTA) Three rectifier transformers were planned to be tested: 2. ABB Transformer, in Alma plant 3. TTI Transformer in Laterrière plant any p m o 4. CWC Transformer in n Arvida g C plant

ri

ee ngin

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Testing Rectifier-Transformer, March 2012

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2. Case Study- RTA in Alma Test was not done, but we observe the following •

HV Bushings are in enclosure duct separated from H0 H1 H2 H3

ring e e in

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an p m o

C

H0

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H0 bushing will not be shorted to the phase bushings for overall test.

Testing Rectifier-Transformer, March 2012

2. Case Study- RTA in Alma Test were not done, but we observe the following Rectifier has DC interconnection, so this transformer should be tested as 2winding when connected to rectifier LV1

any p m Co LV2

ng

eri e n i ng

HV

•

le E b o ©D

+

-

Testing Rectifier-Transformer, March 2012

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3. Case Study- RTA in Laterrière Pot line substation single line

ny

ble ©Do

ring e e ngin

pa m o C

E

Testing Rectifier-Transformer, March 2012

3. Case Study- RTA in Laterrière Transformer Description: Manufacturer

TTI

Year

1988

Capacity (MVA)

91.73

ny Voltage (kV) HV1, HV2 / 69/0.924;pa 0.924 m o LV1, LV2 gC n i r Configuration DY/DD inee Class

ng

le E b o D

©

ONAN/ODAF

Testing Rectifier-Transformer, March 2012

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3. Case Study- RTA in Laterrière S3

Transformer Description:

S2

S1

∆ (LV1)

a

∆ (LV2) omp

H3 H2 H1

ble ©Do

h12

gC nR1 i r e R2 e n i g n

E

R2

h13 R1

H1 H2 H3

R3

S2

h22 S1

R3 h11

Y ny∆

h23

h21

S3

Testing Rectifier-Transformer, March 2012

3. Case Study- RTA in Laterrière Transformer connected to Rectifier: No DC Interconnection between rectifiers -> 3-winding system Surge Capacitors Disconnected

S3

S2

∆ (LV1)

H1

Y ∆

R2

ng

eri e n i ng

leR3 E b o ©D

∆ (LV2) R1

S1

H2

any p m Co

H3

Surge Capacitors Disconnected

Testing Rectifier-Transformer, March 2012

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3. Case Study- RTA in Laterrière Overall Test results as 3-winding Without rectifier With rectifier Rectifier (10/20/2011) (10/31/2011) Insulation kV Insulation %PF Cap (pF) %PF Cap (pF) any CH + CHL1 10 0.28 34,384 0.33 34,607 p m o CH 10 0.27 33,895 in0.28 g C 34,200 r e CHL1 10 0.26 ngine 477 0.33 401 E le CL1 + CL12 0.5 ob0.24 22,736 0.36 28,591 5,855 D © CL1 0.5 0.23 22,587 0.32 28,438 5,851 CL12 0.5 0.12 150 0.08 152 CL2 + CHL2 0.5 0.23 23,020 0.36 28,756 5,736 CL2 0.5 0.23 22,622 0.38 28,271 5,649 March 397 2012 CHL2 Testing Rectifier-Transformer, 0.5 0.3 0.27 484 86

3. Case Study- RTA in Laterrière Excitation Test results H1 – H3 Test kV

mA Watts

H2 – H1 X

mA

H3 – H2

Watts X

mA Watts

X

224 1254 L 182 1065 L 175 1032 H L anLy p m Exciting current pattern is HLL, due to combined Co the zigzag segments, Delta and Y windings: ering

L

8

e ngin E le Results DobTotal

H3 H2 H1

©

Phase

Delta

Wey

H1-H3

H+h

H+h+H+l

3H+2h+l

Highest

H2-H1

L+h

L+h+ H+h

H+2L+3h

Lower

H3-H2

H+l

H+l+L+h

2H+L+h+2l

Lowest

Testing Rectifier-Transformer, March 2012

h12

h11

h22

h13

h21

h23

18

3. Case Study- RTA in Laterrière Two Methods of Doble Ratio Tests: 1. Standard Test: HV to LV phase as normal ratio 2. Modified Test: Short-circuit one leg of LV winding to eliminate the HV zigzag effect. For example ofyPhase A

n

H3 H2 H1

ng4

le E b o ©D R2

h12

R3

h11

h13

Test Ratio ring e e Line in

h21

R1

h22

pa m o C

HV TTR-Cap + Cable LV Lead

H1-H3/ S2 H1 R1-R3

5

H2-H1/ S1 R2-R1 h23

H2

6

H3-H2/ R3-R2

H3

Ground

R1

H3, R2, R3

R2

H1, R1, R3

R3

H2, R1, R2

S3

Expectation: Both methods won’t obtain NP ratio, but Testing Rectifier-Transformer, March 2012 Method 2 provide consistent ratios among phases.

3. Case Study- RTA in Laterrière Doble Ratio Test results

Winding

NP Ratio Method

H-L1 (S) Y-D

42.96

H-L2 (R) D-D

74.40

1

H1-H3/ X1-X3 85.72

H2-H1/ H3-H2/ X2-X1 X3-X2 104.74

56.61g rin e 1 73.25ine 77.10 ng 81.36 2 le E81.36 Dob 2

56.55

Notes Max %Cv

y

Inconsistent

0.11%

Consistent

80.48 pan

om C56.67

Inconsistent

72.20 81.43

0.05%

Consistent

©

Method 2 provide consistent ratio among phases as expected.  Can be used for condition assessment Testing Rectifier-Transformer, March 2012

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4. Case Study- RTA in Arvida Transformer Description: H1

H2

N1

H2 N1

A2

A3

H3

A4

A1

N2

ny mpa A5

A6 A5 A4 A3 A2 A1 B1 B2 B3 B4 B5 B6

H1

ring e e ngin

Co

H3

le E b o Manufacturer ©D

A6

B3

B2 N2

B1

B4

B5

B6

CWC

Year

1941

Capacity (MVA)

7.5

Voltage (kV) HV / LV1, LV2 Configuration

13.2/0.624; 0.624 D / Y-Y Y-Y

Testing Rectifier-Transformer, ClassMarch 2012

ONAN/ONAF

4. Case Study- RTA in Arvida Test Results • Only Overall test on HV winding, unable to disconnect the surge capacitor ny Historical Data mpa Routine Test Co (2007) (2011) g n i r Insulation Test kV e e gin Cap (pF) %PF Cap (pF) n%PF E oble D © CH + CHL 10 0.81 9,940 0.99 9,986 CH

10

1.14

2,030

1.64

2,038

CHL(UST)

10

0.55

7,910

0.77

7,941

Testing Rectifier-Transformer, March 2012

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4. Case Study- RTA in Arvida Test Results • Excitation tests provide normal pattern (2H, 1L), because no zigzag any p m o H1 - H2 H2 - H3 H3 - H1 gC n i r e e Test gin kV mA Watts e X EnmA Watts X mA Watts bl o D © 6384. 3

816.23

L

5048.1

L

999.79

H

5

L

1068.8

6354

X

L

H

Testing Rectifier-Transformer, March 2012

The 4 Case Studies - RTA Conclusion and Observations: • At the factory, the transformer should be tested as 3winding transformer • Surge capacitor need to be disconnected • H0 will be left out for case 2 (Alma) as experimentation • Transformer should be tested as two-winding anywhen p m o connected to this rectifier with DC interconnection gC n i r • Transformer should be tested ee as three-winding when inwith g connected to this rectifier no DC interconnection n E e l • Zigzag winding Dobaffect the pattern of exciting current © • Zigzag winding affect the turns ratio in single-phase source test. • Use the ratio Method 2 for condition assessment. Testing Rectifier-Transformer, March 2012

21

Testing Rectifier-Transformers

Any questions?

ny

pa m o C

ring e e Pierre Leblanc, n Alcoa gin Mt Holly E Hugo Simard, ble Rio Tinto Alcan ©Do

Long Pong, Doble Engineering

Testing Rectifier-Transformer, March 2012

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eri e n i ng

any p m Co

le E b o ©D

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