WIRES AND TRANSPOSED CABLES IN TRANSFORMERS
Dr. Stefan Beckmöller
ESSEX Germany GmbH
TRANSFORM Partner
Vita
Dr. Stefan Beckmöller
Studies at University
„Metallurgy with focus metal forming“ at RWTH Aachen
PhD at RWTH Aachen
Professional Carreer
Quality Engineer at Kabelwerke Rheydt
Project Engineer at Lackdraht Union GmbH, Arolsen
Head of R&D Lacroix & Kress GmbH, Bramsche
Head of R&D Essex Germany GmbH, Arolsen
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Continuous Transposed Cables
Energy Efficient Transformers
CTC
Continuous Transposed Cable
Source: Siemens AG
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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A brief history
1912
Ludwig Roebel invents single insulated and
transposed strands to replace the large
cross-section conductors that were currently
in use within generator designs
Since 1940
Transformer designs using the idea of
Ludwig Roebel
new challenges relating to efficiency, profitability and
environmental compatibility
CTC requirements
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Why do we use CTC?
high flexibility
length
compensation
reduced electrical
losses
improved cooling
Fast and efficient
winding of the active
part of the
power transformer
due to transposition.
Reduced impact of
magnetic field by
increased surface due
to single isolated strips
and transposition.
(skin + proximity effect)
S
I
A1
E
B
A2
e2
S
Dr. Stefan Beckmöller, Essex Germany GmbH
e1
i
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Requirement to wires in Transformer
Conductivity
Conductor
Mechanic strength
Varnish-insulation
Chemical strength
Cable-insulation
Electric strength
Lifetime
Windability
Dr. Stefan Beckmöller, Essex Germany GmbH
Construction
Process
06.06.2013
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CTC construction
Properties influenced by
Conductor
Insulation
Insulation
Bond
Coat
Bond Coat
Construction
Construction
Process
Process
Reel-type
Cost pressure
CTC – build up
Reel-type
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor
Varnish-insulation
Cable-insulation
Construction
Process
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor: Material
Rod
Soft
Copper
Hard
Conductor
Copper alloys
Aluminium
Dr. Stefan Beckmöller, Essex Germany GmbH
Hard
Cu-ETP1
Cu-OF1
E.g. CPR1, CPR2, CPR3
CuAg 0,03
CuAg 0,10
+ low cost
- low conductivity and stiffness
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Conductor: Material
Copper
Aluminium
red-orange
metallic
Bi-Metall
0,01 %
7,75 %
---
8,92 g/m³
2,70 g/m³
3,63 g/m³
1083 ºC
658 ºC
658 ºC
Linear heat expansion
17,0 x 10-6 1/K
23,5 x 10-6 1/K
Young-modulus
13,0 x 104 MPa
7,1 x 104 MPa
Thermal conductivity
385 W/mK
230 W/mK
240 W/mK
Electric conductivity
> 58,58 m/(Ω mm²)
> 35,67 m/(Ω mm²)
> 37,35 m/(Ωmm²)*
5,741 € / kg
1,416 € / kg
metall+forming
↑ welding
↑ forming
low oxidation rate
↓ welding
high oxidation rate
↓ bending
↓ plastic flow
Aspect
% of geosphere
Density
Melting point
Price (15.04.2013)
General remarks
Dr. Stefan Beckmöller, Essex Germany GmbH
CCA*
(15 %)
↑ welding
↓ recycling
↓ bending
* ↑ = copper @ 5 MHz
06.06.2013
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Conductor: Material
Electric Conductivity
Conductivity
60
electric conductivity [m/Omm²]
Cd
Ag, Zn
55
Sn
50
AL
Mn




Copper
pure Copper
Silver
Aluminium
> 58,58
≈ 60
≈ 62
≈ 36
Impurities reduces conductivity
45
Silver has less impact to conductivity
Co
40
Fe
35
P
30
0 ,0 0
0 ,0 2
0 ,0 4
0 ,0 6
0 ,0 8
0 ,10
Hardening reduces conductivity
Cu-ETP1 and Cu-OFE 99,99 %
copper content
0 ,12
m ixture in m ass-%
source: DKI
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor: Material
Mechanical strength
creep behavior of materials after
1.000 h
OF-Cu Ag
material begins to anneal with
temperature
impurity silver enhances
mechanical behavior without
dramatic impact to the
conductivity
Typical alloy CuAg0,03 and
CuAg0,10
OF-Cu
source: DKI
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor: Material
Copper Rod Production
Metallurgy
Electrolyse
Continuous Rod Casting
Up-Cast Verfahren
Source: Aurubis
Dr. Stefan Beckmöller, Essex Germany GmbH
Source: Aurubis
06.06.2013
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Conductor: Material
Rectangular Wire Production
Pre-material
Dr. Stefan Beckmöller, Essex Germany GmbH
Drawing
Rolling
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Conductor: Material
Conform Technology
Advantage
Disadvantage
• Direct production from rod to square
size
• No annealing necessary
• Clean surface of the pressed material
(no fat, flaks, …)
• Set up times low
• Flexible in dimension and shape
• No emulsion necessary
• “Slow” production process
• Sensitive to cleanness off pre-material
• Soft material sensitive to scratches and
oxidation
• Increased copper scrap
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor
Varnish-insulation
Cable-insulation
Construction
Process
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Varnish insulation: Material
Polyvinylacetal
Excellent adhesion, flexibility and oil resistance
Polyesterimid +
Polyamidimid
Increased heat resistance
Comparable with impregnation varnishes
strand
EpoxyBond coat
Specials
Dr. Stefan Beckmöller, Essex Germany GmbH
Standard
Concentric
Improved
Partial
PET- foil, Aramid- paper,
Prepreg, glass yarn, …
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Varnish insulation: Material
Electric Insulation
today 90 % PVA - class 120
break down voltage > 50 V/µm
reduced contact failure
insulation resistance > 500 M km
Insulation types
Introduction of isolation types
240°C
better workability
higher temperature class
higher abrasion withstand
higher bond strength
120°C
Dr. Stefan Beckmöller, Essex Germany GmbH
Polyimid
1958
Polyamidimid
1964
Polyesterimid
1962
Polyester
1955
Polyurethane
1950
Polyvinylacetal 1938
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Varnish Insulation: possible solutions
Polyvinylacetal
Polyurethan
T. Poly. (imid)
Polyamidimid
Polyimid
+
Polyamidimid
Temperature-index
Temperature-index
Temperature-index
Temperature-index
Temperature-index
120 ºC
180 ºC
200 ºC
220 ºC
240 ºC
Heat shock
Heat shock
Heat shock
Heat shock
Heat shock
155 ºC
200 ºC
220 ºC
240 ºC
260 ºC
Resoftening temp.
Resoftening temp.
Resoftening temp.
Resoftening temp.
Resoftening temp.
> 215 ºC
> 250 ºC
> 340 ºC
> 400 ºC
> 500 ºC
soldering
Soldering
soldering
soldering
soldering
no
yes
no
no
no
Chem. Resistance
Chem. Resistance
Chem. Resistance
Chem. Resistance
Chem. Resistance
very good
good
good
very good
very good
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Varnish insulation: Material
Mechanical strength
(bond coat)
Bond Coat (Epoxy)
increased strength at working
condition (5 x stiffness @ 120 °C)
6000
bonded
Force [N]
5000
compatibility with transformer oil
4000
3000
2000
hardening during drying process
(start @ 90 °C depending on type
in hot air or vapour phase)
1000
0,0
Stiffness factor
shelf life min. 6 month depending
bond type and climate
1,0
1,5
2,0
2,5
3,0
3,5
4,0
30
25
simple usage
0,5
Bending [m m ]
different application possible:
all around radial bond
not bonded
0
26,6
24,8
20
15
12,5
10
7,8
5
6,4
0
20°C
60°C
80°C
105°C
120°C
Temperatur
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Varnish insulation: Application
Product
~ 26 m
Process
Isolation increase:
~ 0,10 mm
10 layers with 0,005 mm
thickness
Bdv > 2 kV
Source MAG
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor
Varnish-insulation
Cable-insulation
Construction
Process
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Cable insulation: Material
smooth
But to but wrapping
Cellulose
Micro crepe
Aramid
High thermal resistance, high mechanic strength,
Resistance against oil,
Without wrapping
Protection
paper *
Perforated*
Aramid
Cordex *
PET Filament
Diamond*
Aramid
Specials
Glass yarn, …
Continuous
Transposed Cable
* Essex Patente
Dr. Stefan Beckmöller, Essex Germany GmbH
staggering
Without inter column separator
Gap
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Cable insulation: Material
Electric Insulation
advantage:
- thick insulation
- dielectric strength
in oil
different types:
- Cellulose
- Aramid
disadvantage:
- cooling behavior
- thermal aging
Paper types for electric insulation
Papertype
Remarks
Kraft- Paper
5A2-1H1, paper with high purity
Kraft- Paper, calendared
5A4-1M2, high density and break down voltage
Thermo stabilized
5A2-1M1, increased thermal resistance
Thermo stabilized,
calendared
5A4-1M2, high density and break down voltage,
increased thermal resistance
Thermo stabilized,
calendared, crepe
Paper with high mechanical strength, used for outer
layers
Epoxy coated,
Thermo stabilized
Bondable outer layers
Aramid
High thermal resistance, used for traction transformers
Epoxy coated Aramid
Bondable outer layers for traction transformers
Transformer- Pressboard
P 2.1, inter column separator
Glass woven fabric
Winding used for resin cast transformers
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Cable insulation: Material
Electric Insulation
for low voltage
winding with
CTC with improved cooling (low voltage winding)
perforated
Paperless CTC
diamond
Cordex
increased heat
transfer
increased filling
factor
reduced cooling
higher efficiency
in power transformers
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Cable insulation: Process
Paper wrapping process
application of inner layers
Typical paper set up for CTC
2 outer layers, 50 % staggering
inner layers but to but, ~ 30 % shifted
outer layer
inner layer
CTC
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Conductor
Varnish-insulation
Cable-insulation
Construction
Process
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Cable insulation: Construction
I
pitch
Transposing factor
d
SR
fR
n
SR
b
d = Winding diameter
n = number of strands
b = width of conductor
c = crank length
Dr. Stefan Beckmöller, Essex Germany GmbH
Radial Size HR =
(odd numbers)
Radial Size HR =
(even numbers)
n 1
a E
2
n 2
a E
2
Axial Size BA = 2 b
Intercolumn Paper I =
(min. 8 mm)
E
Z
Z
I Z
n 1
b E
2
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Cable insulation: Construction
Dimension range of strands in CTC
Limits of Transposed Cable
Transposition head
3,10
12,50
thickness [mm]
3,50
3,15
3,00
2,50
3,5 … 39 mm²
2,00
mm
< 79
Axial size
mm
< 26
Crank length
mm
15 - 50
Geometry
1,50
1,00
1,00
0,50
0,00
1,00
Radial size
3,00
5,00
7,00
9,00
11,00 13,00
Transposing factor
>5
ratio width/thickness
<8
width [mm]
Other dimension on request possible
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Cable insulation: Construction
Limits of Transposed Cable
Limits of Transposed Cable
the radial size is depended from
ratio pitch / crank length
CTC with a high ratio width /
height incline to tilt
Small transposing factors
increases the radial size
HR
c
the crank length increases with the
width of the strand
b
Dr. Stefan Beckmöller, Essex Germany GmbH
SR/c
06.06.2013
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Conductor
Varnish-insulation
Cable-insulation
Construction
Process
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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CTC Production Process
Pay off
Transposing
head
Dr. Stefan Beckmöller, Essex Germany GmbH
Paper Wrapping
Caterpillar
Winder
06.06.2013
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CTC Production Process
Work principle
Stack pusher
Production
Counter holder*
Strand pusher
Rotation
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Test and specification
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Tests and specification
specification
Copper
DIN 1977
Aluminium
DIN EN 573-3
Rectangular magnet wire – general requirements
IEC 60317-0-2
Magnet wire – specific requirements
IEC 60317-..
Magnet wire – test method
IEC 60851-..
Magnet wire – temperature index
IEC 60172
Cellulosic paper
IEC 60554
Aramid - Paper
IEC 60819
Pressboard
IEC 60641
Drums and spools
Dr. Stefan Beckmöller, Essex Germany GmbH
DIN 46391/1, IEC 60264
06.06.2013
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Product test
Shorts in CTC
Bonding
Elongation
Spring Back
Sizes
CTC
Snap test
Yield strength
Abrasion
tan delta
Adhesion
Break Down
Voltage
Staggering;
bulging
Heat Shock
Oil Compatibility
El. Resistance
Softening
Temperature
Test depending to magnet wire
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Summary
Continuous Transposed Cable look simple but are a “high tech”
product
Continuous Transposed Cable are a customized product
A lot of things are possible with a close work together of the CTC
producer and the transformer producer
If the others belief, you're at the end,
now you really have to start.
Konrad Adenauer
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Superior Essex
23 plants in 9 countries
in
America, Europe and Asia
Cable for telecomunication
Round and flat enameled wires out of
copper and aluminium
Covered products
Continuous Transposed Cables
Isolation varnishes
Copper – Rod
Member of the LS-Cable Group
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
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Thank you very much
for your attention
Dr. Stefan Beckmöller, Essex Germany GmbH
06.06.2013
Page 39