ACCELERATED ELECTRICAL AND MECHANICAL

AGEING TESTS OF HIGH TEMPERATURE LOW

SAG (HTLS) CONDUCTORS

Dominik Stengel, Richard Bardl (BAM)

Christian Kühnel, Steffen Großmann (TU Dresden)

Wilhelm Kiewitt (50Hertz)

27-April-2017

The idea

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 2

Expansion of transmission system

Uprating of transmission lines

HTLS conductors

Higher capacity due to higher rated temperature

- Lower sag (thermal expansion)

- Temperature resistant materials

Limited long-term experience!

Expansion of transmission system

Uprating of transmission lines

HTLS conductors

Higher capacity due to higher rated temperature

- Lower sag (thermal expansion)

- Temperature resistant materials

Material degradation? (RTS,electrical resistance, creep…)

Selected conductors

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 3

conductor Core material Outer layers Structure

ACSR Steel Hard drawn aluminum

ACCC,

ACPR

Polymer matrix

composite

Annealed or thermal aluminum

ACCR Metal matrix

composite

Thermal aluminum

GZTACSR

„Gap“

Steel Thermal aluminum

Also tested: ACSS, ZTACIR, TACSR

Conductor ageing

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 4

Reality(50 years)

Laboratory(6 months)

Everyday stress, Tensile forcewind loads

Thermal and electrical Maximum rated and loads emergency temperature

Corrosion (temperature, not studiedenvironment)

Tensile force

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 5

Applied tensile force = Static load + Cyclic load

Static load (Everyday stress)

- Calculated for an ideal single span of 413 m and 15.5 m sag

ca. 15 % RTS (depending on the conductor‘s specific

weight)

From wind velocity to tensile force

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 6

Wind velocitiesin 50 years

According to EN 1991-1-4

(10 m height, wind zone 2,

rural terrain)

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uen

cy i

n 5

0 y

ears

10 15 20 25

0.2

0.4

0.6

0.8

1

ann

ual

pro

bab

ilit

y,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

vb i

n m

/s10 15 20 25

10

20

30

40

50

vb in m/s

freq

uen

cy i

n 5

0 y

ears

10 15 20 25

0.2

0.4

0.6

0.8

1

ann

ual

pro

bab

ilit

y,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

vb i

n m

/s

From wind velocity to tensile force

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 7

5 classes ofwind speeds

Wind velocities

in 50 years

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uen

cy i

n 5

0 y

ears

10 15 20 25

0.2

0.4

0.6

0.8

1

annual

pro

bab

ilit

y,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

vb i

n m

/s

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uenc

y in

50

year

s

10 15 20 25

0.2

0.4

0.6

0.8

1

annu

al p

roba

bili

ty,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

v b in

m/s

From wind velocity to tensile force

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 8

Turbulent wind fieldbased on provisions

5 classes ofwind speeds

Wind velocities

in 50 years

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uen

cy i

n 5

0 y

ears

10 15 20 25

0.2

0.4

0.6

0.8

1

annual

pro

bab

ilit

y,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

vb i

n m

/s

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uenc

y in

50

year

s

10 15 20 25

0.2

0.4

0.6

0.8

1

annu

al p

roba

bili

ty,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

v b in

m/s

Generation of a 10

minutes wind field

From wind velocity to tensile force

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 9

Tensile force on conductor based on

FE simulation

Validated FE-model for

existing overhead line in

Northern Germany

Turbulent wind field based on

provisions

5 classes ofwind speeds

Wind velocities

in 50 years

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uen

cy i

n 5

0 y

ears

10 15 20 25

0.2

0.4

0.6

0.8

1

annual

pro

bab

ilit

y,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

vb i

n m

/s

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uenc

y in

50

year

s

10 15 20 25

0.2

0.4

0.6

0.8

1

annu

al p

roba

bili

ty,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

v b in

m/s

From wind velocity to tensile force

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 10

Turbulent wind field based on

provisions

Tensile force on conductor based on FE simulation

5 classes ofwind speeds

Wind velocities

in 50 years

- Equivalent harmonic

forces with defined

mean, amplitude and

number of cycles using

rainflow count

- Reduction to 3 cyclic

loads and amplitudes

using Palmgren-Miner

Defined cyclictensile force

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uen

cy i

n 5

0 y

ears

10 15 20 25

0.2

0.4

0.6

0.8

1

annual

pro

bab

ilit

y,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

vb i

n m

/s

10 15 20 25

10

20

30

40

50

vb in m/s

freq

uenc

y in

50

year

s

10 15 20 25

0.2

0.4

0.6

0.8

1

annu

al p

roba

bili

ty,

p

0 500 100010

15

20

25

cumulative frequency for 50 years

v b in

m/s

Cyclic loading for ACSS (RTS = 156 kN)

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 11

Minimum load [kN] Maximum load [kN] Number of cycles

Static loading 24 24 Constant

Wind load 1 24 33 141,780

Wind load 2 29 37 3300

Wind load 3 33 41 30

x 150 days at 200 °C

Testing rack for artificial ageing

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 12

- Test of 4 different conductor types simultaneously in two parallel lines

- Conductor length of approximately 20m

Testing rack in Ragow (Germany)

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 13

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 14

Creep

Single wire

stress strain

Conductor stress strain

Self-damping

Ductility test on wires

Grease test

Electrical resistance

(TU Dresden)

Electrical and mechanical accessories

tests

Conductor tests

Test result: Tensile strength of aluminum

- Ageing 4000 h at 210 °C, 400 h at 240 °C

- ZTAL (AT3, aluminum-zirconium-alloy)

- Tensile strength decreased of 29 % after

ageing

18-May-17 Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors Workshop 15

Sample Standard New AT3 Aged AT3

1 2.37 kN 2.58 kN 1.75 kN

2 2.37 kN 2.49 kN 1.73 kN

3 2.37 kN 2.36 kN 1.78 kN

Accelerated Electrical and Mechanical Ageing Tests of HTLS Conductors 16

Summary

– Scientific development of an artificial ageing regime

– Successful implementation in a test stand

– Ageing of 8 different conductor technologies

– Extensive mechanical and electrical test program prior and after

ageing

– First test results show interesting ageing effects

– Overall results expected at the end of 2017