Preventing & Identifying Failures of Dead Break Elbows Wind - - PowerPoint PPT Presentation

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Preventing & Identifying Failures of Dead Break Elbows Wind - - PowerPoint PPT Presentation

Aug 12, 2023 530 likes •992 views

Preventing & Identifying Failures of Dead Break Elbows Wind Farm Applications 1 Introduction Brian Peyres, Senior High Voltage Reliability Engineer, EDP Renewables. Level 2 Thermographer with 20 Years in the generating and utility

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SLIDE 1

Preventing & Identifying Failures

  • f Dead Break Elbows

Wind Farm Applications

1

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SLIDE 2

Introduction

2

  • Brian Peyres,

Senior High Voltage Reliability Engineer, EDP Renewables.

  • Level 2 Thermographer with 20 Years in

the generating and utility industry.

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SLIDE 3

Introduction

3

  • Dead break elbows are commonly used by

utilities and wind energy generators.

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SLIDE 4

Introduction

4

  • Dead break style connections are a

reliable connection if installed and maintained correctly.

  • This presentation will highlight nearly 6

years of work investigating failures and developing preventative maintenance plans to eliminate termination failures.

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SLIDE 5

Wind Farm Collection Systems

5

  • 10-17 turbines with a generating capacity

up to 28 MW per circuit are typical.

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SLIDE 6

Wind Farm Collection Systems

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  • Up to 165 high voltage terminations per

circuit.

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SLIDE 7

Wind Farm Collection Systems

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  • Average of 1300 high voltage terminations

per 200MW wind farm.

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SLIDE 8

Faults

8

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SLIDE 9

Faults

9

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SLIDE 10

Faults

10

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SLIDE 11

Faults

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SLIDE 12

Faults

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SLIDE 13

Faults

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SLIDE 14

Faults

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SLIDE 15

Faults

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  • At our peek we were losing on average

2% of our assets due to termination failures.

  • This means roughly 35 circuit failures per

year.

  • Considering generation losses, damaged

equipment and labor each circuit failure could result in nearly $ 80,000 in total losses.

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SLIDE 16

Maintenance

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  • In early 2010 we began an aggressive

Infra-Red inspection approach.

  • The results of the IR scans were quite

alarming.

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SLIDE 17

The finds over the years

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SLIDE 18

The finds over the years

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Damaged Stud and surface pitting

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SLIDE 19

The finds over the years

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SLIDE 20

The finds over the years

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SLIDE 21

The finds over the years

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SLIDE 22

The finds over the years

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Screwdriver used during construction to twist and form cable termination into position.

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SLIDE 23

The finds over the years

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Cross threaded stud resulting in metal shavings and poor connection.

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SLIDE 24

The finds over the years

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End cap could be removed by hand when this unit was repaired.

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SLIDE 25

The finds over the years

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SLIDE 26

The finds over the years

26

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SLIDE 27

The finds over the years

27

Notice the anomaly at the back of the T body? Loose connection was found internal to the transformer under oil.

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SLIDE 28

Why?

28

  • 1. Connection not properly tightened.
  • a. Ensure termination is free of defects and

mating surfaces are parallel to each other.

  • b. Tighten the end plug as much as possible by

hand.

  • c. Tighten to 55 ft-lbs.
  • d. Check fitting by moving T-body front to back.
  • e. Torque again to 55 ft-lbs.
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SLIDE 29

Why?

29

  • 2. Contamination
  • a. Watch for metal shavings, caused by

the termination resting on the stud as it is placed into position.

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SLIDE 30

Why?

30

Metal shavings resulting in poor contact and damaged threads.

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SLIDE 31

Why?

31

  • 3. Environmental Stresses
  • a. Water collecting in the lower end of the

vault can freeze and add weight to the cable.

  • b. Thermal cycling is common on wind

farm equipment. This continuous thermal movement could have effects

  • n termination reliability.
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SLIDE 32

Why?

32

Support bar and cable clamps added to help mitigate movement and support weight.

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SLIDE 33

Why?

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  • 4. Studs !

Watch out for imitations !

Studs supplied by transformer manufacturer.

Not uniform, various lengths and poorly machined.

Studs supplied by T-Body manufacturer.

Uniform in shape, same length.

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SLIDE 34

Why?

34

Shown here is a stud from the T-Body manufacturer

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SLIDE 35

Why?

35

A B C D E

Overall Flange Threads Origin "E" Diameter "A" Length "B" Length Depth "C" Bottom "D" Top T-Body Manf. 15.25 61 14.3 1.25 23.5 23.5 T-Body Manf. 15.25 61 14.3 1.25 23.5 23.5 T-Body Manf. 15.25 61 14.3 1.25 23.5 23.5 T-Body Manf. 15.25 61 14.3 1.25 23.5 23.5 Tranformer Manf. 15.5 63 10.25 1 26 26.75 Tranformer Manf. 15.25 63.5 10.5 1.25 26.5 26 Tranformer Manf. 16 65 10.25 1 28 26.75 Tranformer Manf. 15.25 63 10 1 26 27 Tranformer Manf. 15.25 66 9.75 1.5 29 26.5 Tranformer Manf. 15.5 63 8 1.25 29 26 Tranformer Manf. 15.5 63 9.5 1.5 27.5 26 Tranformer Manf. 16 62.5 10.5 0.9 25 27 Tranformer Manf. 16 63 10 1.5 27 26

Not a single stud supplied by the transformer manufacturer were machined to the same dimensions as the T-Body manufacturer.

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SLIDE 36

Why?

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End of the stud at a wider diameter than the inner. Damaged or poorly machined studs will not fully seat, this will result in a false positive torque.

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SLIDE 37

What it should look like

37

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SLIDE 38

What it should look like

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This area must be free

  • f debris, secure and

tight.

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SLIDE 39

Experiment Time!

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15 minutes into 100amp test. Bare connector 44.2°C Shielded boot 26.9°C ΔT 17.3°C

This area must be free

  • f debris and secure

and tight.

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SLIDE 40

Experiment Time!

40

This area must be free

  • f debris and secure

and tight.

45 minutes into 100amp test. Bare connector 69.6°C Shielded boot 35.7°C ΔT 33.9°C

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SLIDE 41

Experiment Time!

41

This area must be free

  • f debris and secure

and tight.

75 minutes into 100amp test. Bare connector 72.3°C Shielded boot 40.9°C ΔT 38.4°C

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SLIDE 42

Experiment Time!

42

This area must be free

  • f debris and secure

and tight.

75 minutes into 100amp test. Bare connector 72.3°C Shielded boot 40.9°C ΔT 38.4°C Good rule of thumb, add a multiple of 1.8 to what you read outside to estimate what your generating inside.

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SLIDE 43

Why?

43

  • False positive torque or poor

craftsmanship =

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SLIDE 44

Questions?

44