Special Issue

Technologies supporting the achievement of Furukawa Electric Group
Medium-term Management Plan 2022 - 2025
Contribution to the achievement of SDGs
by Furukawa Electric Group

Contribution to R&D of Power Cable Systems
by Applying Computer Simulation
Satoru Maruyama*1, Sakurako Tomii *1, Yudai Tomita*1, Yuki Matsumoto*2

In the Power Cable Division, we are focusing on the fields of submarine cables
for renewable energy, direct current (DC) cables, and ultra-high voltage underground cables as the pillars of our efforts toward a decarbonized society and our Medium-termManagement Plan 2022-2025 (2025 Mid-term Plan). The activities in order to increase the efficiency of product developments using scientific calculations are underway. This paper is
described about the results obtained from the evaluation of steel wire armour loss in submarine
cables, the evaluation of DC insulation materials based on quantum chemical calculations, andthe simulation of the internal pressure when a ground fault occurs at cable terminations. It would
be expected that these achievements will not only achieve our company’s goals but will also
contribute to technological developments on the power cable.

ABSTRACT1.

INTRODUCTION

The Power Cable Division has adopted submarine cables
for renewable energy, DC cables, ultra-high voltage
underground cables, etc. as the pillars of our 2025 Midterm Plan, and is promoting related technology developments. In the past, as the design and development of
power cables has focused on empirical methods, inwhich sample evaluations are followed by actual cableevaluations, the development period tended to be lengthened. Moreover, there is also a problem that the manufacturing of prototypes on the production line becomes afactor that inhibits the factory operating rate.
On the other hand, in industrial fields such as automobiles, design using computer aided engineering (CAE) is
commonly performed. This not only reduces the time andthe cost required for actual machine testing, but also
reduces the dangers hidden in actual machine testing,which is considered to be a great advantage in terms ofsafety.
In the field of power cables, as voltages and capacities
are increasing, experiments involving dangerous factors
such as high voltages and large currents are essential forcharacterization. Therefore, it is considered that it is possible to reduce the risk associated with experiments byproceeding with a basic design based on CAE and only
performing final verification at the actual cables. In addi*1*2tion, although alternating current (AC) power transmission
is generally adopted, it is known that the materials themselves which make up the power cable generate losses
due to AC magnetic fields, resulting in power transmission losses. The accurately estimation of these losses byapplying the electromagnetic field is also effective fordesigning efficient transmission capacities.
Moreover, it is necessary to process at the atomic andthe molecular levels which make up matters when considering material development. In the development ofcable insulation materials, by incorporating the conceptof quantum chemistry which has not been used much, it
is possible to explain how insulation performance is efficiently expressed, and attempts are also being made toapply this to logical material design.
As described above, elucidation of physical phenomena through simulations based on CAE and scientific calculations is expected to become even more important for
efficient development. Therefore, we are expanding theirapplications to design and develop to the power cablesystems as well.
This paper presents the evaluation of material properties of DC insulating materials based on quantum chemical calculations, pressure simulation in cable termination
when a ground fault occurs, and the optimization of steel
wire armour losses in submarine cables as examples andshows the consistency between actual application examples and verification test results.

Cable System R&D Department, Power Cable Division
Cable System Engineering Department,
Power Cable Division

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Contribution to R&D of Power Cable Systems by Applying Computer Simulation

When a DC voltage is applied, a dielectric phenomenon
peculiar to DC occurs in which electric charge accumulates (accumulation of space charge) inside the solid insulating materials used in cables and joints. Therefore, thedevelopment of materials which do not accumulate spacecharges has been being required. As a method for evaluating the accumulation of space charge, a method ofexperimentally measuring and evaluating is generally
used. However, preparing evaluation sample materials
and measuring all of them in the material development
process poses the problem of cost and time.
On the other hand, the use of quantum chemical calculations is known as a method for predicting the movement of electric charges from the chemical structure ofmaterials and evaluating their space charge characteristics 1). This method enables the desk study of the spacecharge characteristics before measurement. This section
introduces an example of an approach using quantum
chemical calculations to evaluate the space charge characteristics of the main insulating material developed for
applying to DC cable system.
A method for determining space charge characteristics
from quantum chemical calculations will be explainedusing Figure 1. As an index for evaluating properties, thepresence or absence and the size of the generation of anelectric double layer and a trap level for each material areused and have a very large effect on the space charge
characteristics.
Figure 1 shows an example of the energy potentials of
the calculation model. From the energy potentials, thehighest occupied molecular orbit (hereinafter referred toas HOMO), the lowest unoccupied molecular orbit (hereinafter referred to as LUMO), and the median value of the（a）region (forbidden band) between HOMO and LUMO
- called the Fermi level - were calculated. When a voltage
is applied to an insulating material, the sample (S) is
sandwiched between semiconducting (SC) or metallic (M)materials. The Fermi levels of semiconducting and metallic materials were set as fixed values, respectively, andthe difference with the Fermi level of the sample wascompared (Figure 1 (a): ΔE (SC-S), ΔE (M-S)). The larger
the Fermi level difference, the easier it was for charges tobe injected from the conductive material because a layer
called an electric double layer was generated between
the sample and the semiconducting/metal interface after
the voltage application. In other words, the difficulty informing an electric double layer leads to suppress spacecharge accumulation.
Furthermore, it is important to provide a mechanism
called a trap level to prevent the free movement of charges when charges are injected into the sample. Dependingon the molecular structure, trap levels (Figure 1 (b): Etrap(LUMO), Etrap (HOMO)) are generated where the charge
density is locally concentrated. The deeper the trap level,
the more difficult it is for the charge to transfer. From thequantum chemical calculation results of each material,
the difficulty of the charge injection is determined fromthe Fermi level difference between the sample and the
conductive material, and the difficulty of the charge transfer is determined from the depth of the trap level, thereby
evaluating the space charge characteristics.
Here, the space charge characteristics about the following material were estimated from quantum chemical
calculation results. One is the cross-linked polyethylene(XLPE) with a chemical structure of suppressing thecharge accumulation which was developed for DC cableuse (Hereafter, called DC-XLPE). The other is the ethylene
propylene diene rubber (EPDM) used for the main insulation of the intermediate joint for DC cable system.

（b）

Sample (S)Sample (S)Trap level

ΔE(SC-S)
Etrap(LUMO)

Figure 1

HOMO

ΔE (M-S)

ΔE(M-S)

Double electric layer

Etrap(HOMO)

Metallic material(M)

Fermi level

Metallic material(M)

ΔE(SC-S）

Semiconductive
material(SC)

Energy / eV

LUMO

Semiconductive
material(SC)

2.

CHEMICAL CALCULATIONS OF DC
INSULATING MATERIALS

Energy / eV2.

Trap level

Characterization of space charge: (a) before voltage application (b) after voltage application.

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Contribution to R&D of Power Cable Systems by Applying Computer Simulation

（a）

（b）

5

5

ΔE (SCEPDM)

Etrap (LUMO)
LUMO

Fermi level-10

Semiconductive
Material (SC)-5

Figure 2

Etrap(HOMO)
HOMO

HOMO
Etrap(HOMO)

Trap site-0.6 -0.4-0.2

0es the charge accumulation was working effectively. In
the case of the EPDM shown in Figure 3 (b), traps as
deep as in the DC-XLPE were not generated, but a positive charge trap structure was partially formed. It is considered that a diene structure having a double bond has agood effect on the space charge characteristics.
Quantum chemical calculations were used to evaluate
the space charge characteristics of the insulating materials for cables and joints used in DC cable systems, and it
was confirmed that they have good space charge characteristics. Pre-qualification (PQ) tests for DC 525 kV classcable system including cable, joints and other accessories using insulating materials described in this section
have been performed, and they have been certified bythird-party organizations2), 3).
Accordingly, it was confirmed that the insulating material developed were suitable for DC use.
As mentioned above, it is expected that these techniques by promoting for evaluations which combine
quantum chemical calculations and space charge measurements would be contributed to accelerating thedevelopment speed in the future insulating material
development process.

3.

（b）

Trap site

0.2

0.4

0.6

0.8

Energy / eV
Figure 3

Fermi level

Energy potential of the DC-XLPE and the EPDM: (a) DC-XLPE (b) EPDM.

（a）

-0.8

Deep traps at both
LUMO and HOMO levels-10

Figure 2 shows the energy potentials of the DC-XLPE
and the EPDM. As shown in Figure 2 (a), the Fermi level
difference between the DC-XLPE and the semiconducting
material was very small, so an electric double layer was
not generated and the charge injection was difficult tooccur. Furthermore, there are few space charges accumulation because it had a structure of suppressing acharge transfer due to a generation of deep trap level inthe LUMO level.
Next, as shown in the Figure 2 (b), it is found that
EPDM is the material which the charge injection was easy
to occur because the Fermi level difference between the
EPDM and the semiconducting material is large, and alarge number of electric double layers were formed.
However, since relatively deep trap levels were generated
at both the LUMO level and the HOMO level, the chargetransfer was suppressed, which is considered to have apositive effect on the space charge characteristics.
Figure 3 shows the results of visualizing the charge
density by mapping the charge density ratio in three
dimensions. The DC-XLPE shown in Figure 3 (a) is characterized by a trap structure with a large negative charge.
Deep traps were also confirmed from the energy potential, and it is considered that the structure that suppress--1-5

Doubleelectric layer
Semiconductive
Material (SC)ΔE (SCDCXLPE)

0Energy / eV

Energy / eV

Deep trap
at LUMO level

No double
electric layer

0

Etrap (LUMO)
LUMO

3D electrostatic potential of the DC-XLPE and the
EPDM: (a) DC-XLPE (b) EPDM.

3

1

NUMERICAL ANALYSIS OF THE CABLETERMINATION AT GROUND FAULT(ESTIMATION OF THE MAXIMUMPRESSURE)

As the capacity of power cables increases, there are concerns about increased damage in the event of an accident due to insulation breakdown, etc., and about thelengthening duration of the restoration work. In such a situation, as the terminations of power cables are designed
to be filled with insulating oil, damage to peripheral
equipment due to the damage of hollow insulators andenvironmental pollution damages due to the oil leakage
can be expected if a ground fault occurs inside the termiFurukawa Electric Review, No. 54 2023

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Contribution to R&D of Power Cable Systems by Applying Computer Simulation

Test sample (composite hollow insulator)

Explosive cartridge

Figure 4

The test results are shown in Figure 5. The solid line is
the pressure transition of the sample without a rupture
disk, and the dashed line is the one with a rupture disk. In
the sample without a rupture disk, the maximum pressure
increased to 12.0 MPa, but no damage was observed in
the hollow insulator and the sealing part, and the sealing
performance was maintained. On the other hand, in thesample with a rupture disk, the rupture disk operated at
the same time as the pressure increased and released thefilled water. As a result, the maximum pressure was 9.0
MPa, the pressure rise after 15ms was very small, and thepressure release effect was confirmed after 15 ms. In
addition, no damage was observed inside the sample andin the sealing part even in the sample with a rupture disk.
15

Without a rupture disk
With a rupture disk

Pressure / MPa

nations. Therefore, there is a growing demand for a pressure relief mechanism at the termination to reduce damages in the event of an accident. Although a ground fault
test is required for the performance verification in order toinstall the pressure relief mechanism, there is the problem
of significant high cost because of safety and environmental measures in its test. Therefore, it is necessary to
reproduce ground fault tests by numerical analysis andreduce the number of tests for design reviews. In here,
focusing on the pressure generated when a ground fault
occurs, we performed a ground fault equivalent test inorder to establish an internal pressure estimation technology, set parameters based on the obtained results, andcalculated changes in the internal pressure.
First, in order to understand the relationship between
the ground fault energy and the generated pressure whena ground fault occurs, a ground fault equivalent test was
performed using a scaled-down model to confirm thedurability of the hollow insulator and verify the peak pressure.
In the ground fault equivalent test, explosives wereused to generate pressure in order to simplify the relationship between the input energy and the generated pressure. The sample is a polymer composite hollow insulator
used in a 66 kV class termination. As a pressure source,four cartridges containing explosives were connected tothe bottom of the hollow insulator, the explosives wereburned inside each, and the combustion gas was applied
to the inside of the hollow insulator (Figure 4). The
amount of explosive charged was calculated from the firstpeak value of the energy of the ground fault current whena ground fault occurred. Each cartridge was charged with
1.5 g of black powder and 5.0 g of smokeless powder
and the four cartridges were ignited simultaneously. In
this test, for safety reasons, the inside was filled withwater instead of insulating oil. The internal pressure wasmeasured with a pressure sensor connected to the upper
part of the hollow insulator. Furthermore, in order to confirm the pressure transition and a maximum pressure
value with the pressure relief mechanism, the samples
with/without a rupture disk connected to the upper sealing plate were prepared. Here, a rupture disk used was
the valve to burst at 0.6 MPa.

10

5

0

0

Figure 5510Time / ms

15

20

Measurement results of the internal pressure in thehollow insulator in the ground fault equivalence test.

This ground fault equivalent test was reproduced bynumerical analysis using the finite element method. Since
the ground fault phenomenon causes the pressure tochange rapidly in a short time, it is necessary to solve thestate equation which takes into account the impact of theshock wave. LS-DYNA was used as an analysis solver,
and in this analysis, the pressure of the fluid inside thehollow insulator (p) was obtained using the MieGrüneisen state equation given by equation (1) 4).

ρ0 c 02 µ [1 + (1 − Γ ) µ]
[1 − ( s − 1) µ]02p=+ Γ0 E
(1)2Here, ρ 0 is the density, c 0 is the speed of sound, μ is thevolume compressibility, s is the coefficient of the relational expression between the shock wave velocity and thematerial particle velocity, and Γ0 is the Grüneisen constant. The values in Table 1 were set for each. In addition,
E is the internal energy density of the material, and in thesimulation analysis, the start time was the instant when
the high-pressure gas flew into the hollow insulator, andthe initial energy density was set so that the initial pressure inside the cartridge was 8.85 MPa, as shown in
Table 1.

Sample for the ground fault equivalent test.

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Contribution to R&D of Power Cable Systems by Applying Computer Simulation

Parameters for the simulation.
SymbolValue

ρ₀1.00 × 10

kg/m3
m/s

nation with a ground fault current of 30 kA for 0.25 seconds. The displacement of the central cable and thestress cone and the displacement of the hollow insulator
surface were neglected. As analysis models, models withand without rupture disks were created. In the model withrupture disks, four rupture disks with the same area as in
the ground fault equivalent test were set, and they were
set to release the silicone oil inside when the pressure
reached 0.6 MPa in each of the rupture disk position.

Unit
3

c₀

1450

μ

1.00 × 10-9

s

1.79

Γ₀

1.65

E

22.1 × 106

J/m3

The analysis result is shown in Figure 6. The solid line is
the result without a rupture disk, and the dashed line is
the result with a rupture disk. In the model without a rupture disk, the maximum pressure was 12.3 MPa, whichalmost matched the peak pressure in the equivalent test,
and the second and subsequent pressure peaks occurredat almost the same timing. On the other hand, comparing
between an equivalent test result and an analysis resultwith rapture disks, the former was indicated a peak pressure value of 9.0 MPa and the latter was 10.2 MPa. And
the occurrence time on their pressure value is earlier in
the analysis result. The cause of this difference is considered that the inflow timing of the pressurized gas from thefour cartridges did not match up in the ground fault
equivalent test.

Pressure / MPa

15

Silicone oil
7.5 m
Ø600

Table 1

Ground fault point(gas application point)

Cable with stress cone(no displacement)

Figure 7

Schematic figure of the simulation model at ground
fault in the 500 kV hollow insulator.

Table 2

Parameters for the simulation of the 500 kV
termination.
Symbol

Value

Unit

ρ₀

9.85 × 102

kg/m3

c₀

985

m/s

μ

9.85 × 10

Without a rupture disks0With a rupture disk

Γ₀

1.65

-8

10

5

0

0

Figure 6510Time / ms

15

20

Simulation results of the interenal pressure in thehollow insulator.

It was confirmed that the analysis result qualitatively
agreed with the test result by providing appropriate initialconditions when compared under the condition without arupture disk. Therefore, the pressure estimation by
numerical analysis is expected to become an effective
mean when examining safety measures, etc. for ground
fault tests if the accuracy of the analysis is improved.
Using this analysis method, the pressure during the
ground fault test of a 500 kV-class termination was estimated. As shown in Figure 7, a model was created inwhich silicone oil was filled inside a hollow insulator witha length of 7.5 m and a diameter of 600 mm, and the MieGrüneisen state equation was calculated with the parameters in Table 2. It was assumed that the ground fault
occurred directly under the stress cone inside the termi-

Figure 8 shows the analysis result. The solid line is theanalysis result without the rupture disk, and the dashedline is the one with rupture disks. In this analysis, since
the ground fault gas continued to be supplied from theground fault point, the pressure continued to rise under
the condition without rupture disks to be estimated toreach 18 MPa or more at 0.25 seconds. On the other
hand, under the condition with rupture disks, the pressure
rise and the pressure reduction effect due to the releaseof the filling oil were balanced, and finally converged at
6.2 MPa. Considering the result of the above-mentioned
ground fault equivalent test, the possibility of damage tothe hollow insulator was low in the model with rupture
disks, and the damage reduction effect of rupture disks is
expected.
This analysis method is helpful for ground fault design
on cable termination for high voltage and large capacity.

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Contribution to R&D of Power Cable Systems by Applying Computer Simulation

Pressure / MPa

20

Without rupture disksWith rupture disks

15

10

5

0

0

0.05

0.1

0.15

0.2

0.25

Time / sFigure 8

4.

Simulation results of the internal pressure at ground
fault in the 500 kV hollow insulator.

ANALYSIS OF STEEL WIRE ARMOUR
LOSS IN SUBMARINE CABLE

Submarine power cables, which are used for offshore
wind power generation, are also becoming higher in voltage and larger in capacity. Figure 9 shows a photographof representative structure for three-core submarine
power cables. A feature of submarine power cables isthat they are provided with an armour layer on the outermost layer for the purposes of distributing installation tension to the seabed and preventing damage, and galvanized steel wires are usually used. This causes the following problems.
Copper Conductor
FOC

XLPE Insulation
Lead Sheath
Galvanized
Steel Wire Armour

Figure 9

An example of a three-core submarine cable.

Power transmission is achieved by the current flowing
through the conductor. At that time, the heat loss is generated inside the cable in operation, and an accurate estimation of these losses are very important in designing thesize of an actual power cable. The reason is follows. In
the actual cable size design, the conductor size is determined by constraining the maximum temperature (generally 90°C) of the cable conductor part in considering heatgeneration by ohmic loss in conductor and armour anddielectric loss, and heat dissipation in cable materials.
Here, if the loss was over estimated, it leads to designinga larger size than necessary. In particular, submarine
power cables use galvanized steel wires as the armour

layer material, as mentioned above. Since steel wire is amagnetic material, it is induced by the electromagnetic
field created by conductor currents, generating eddy currents and circuit currents, resulting in heat loss (calledarmour loss). The armour loss is generally calculatedusing the equation of the International ElectrotechnicalCommission (IEC) standard 5), but it has been qualitatively
suggested that the larger the conductor and the larger thecurrent, the more the armour loss is overestimated 6). In
other words, armour losses are possible to estimate moreaccurately, it will be possible to design a smaller size conductor than the conventional cable. With this in mind,
accurately estimation for armour losses is being studiedin our company 7) and the details are described below.
Finite element analysis (FEM analysis) was applied toevaluate the armour losses. Although it is possible tomeasure the current loss generated in the steel wirearmour layer using an actual submarine cable, it takes
time to prepare for the measurement and to evaluate themeasurement. In contrast, analysis has the advantage ofbeing able to evaluate losses and taking account of
assigning all design parameters, and to derive results in ashort period of time. The basic structure of the three-coresubmarine power cable which is the subject of this study
consists of a power core, in which the conductor throughwhich the current flows for power transmission is covered
with an insulating layer, a lead sheath, and outer sheath.
The three cores are twisted in the longitudinal direction,and the circumference is covered with the steel wirearmour layer in the longitudinal direction. In addition, thephases of the AC currents flowing through the conductorof each of the three cores are shifted by 120 degrees,making the electromagnetic mechanism inside the cable
extremely complex. Since the armour loss that is theobject of this study is the loss that occurs as an electromagnetic element in this cable, it was considered that
evaluation with finite element analysis would be useful.
For the FEM analysis, it was modeled as shown in
Figure 10 since the only metal portions (copper conductor, lead sheath, steel wire armour layer) of the actual
cable structure are affected by the electromagnetic field.
Figure 10 shows also an example of the loss density distribution obtained when calculating with this model.
Conductor
Insulating layer
Lead sheath
Steel wire armor

kW / m3
10
9
8
7
6
5
4
3
2
1
0

Figure 10 An example of loss density distribution in 3D FEM.

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Contribution to R&D of Power Cable Systems by Applying Computer Simulation

1

100
90

λ2_FEM

0.8

80

×100

λ2_IEC

0.7

70

λ2

0.6

60

0.5

50

λ2_IEC

0.4

40

0.3

30
λ2_FEM

0.2

20

0.1

10

0

0

0

500

1,000

1,500

2,000

λ2_FEM /λ2_IEC ×100 / %0.9

And since armor losses are generated by magnetic
fields, we considered that the influence of other metalmaterials should also be considered, and investigated thedependence of armour losses on lead sheath thickness
by FEM analysis as well. Figure 13 shows the results. In
this study, the conductor size was fixed at 1,400 mm2,
and only the lead sheath thickness was changed (275 kV
3x1,400 mm2 submarine cable, outer diameter of φ280mm approx.). In the figure, λ 2_IEC is a value based on the
IEC equation, and since it focuses only on the armour layers, it is a constant value regardless of the lead thickness.
On the other hand, λ 2_FEM showed a smaller value than
λ 2_IEC, and there was a tendency for the value to decreaseas the lead thickness increased. The reason for this result
is considered to be the change in the electromagnetic
field inside the cable and in the armour layers due to thechange in the thickness of the lead sheath. In otherwords, the losses of armour layers are independent fromthe lead sheath thickness in the IEC equation, but it isindicated that the lead sheath layer influenced to armour
losses by using FEM analysis.
100

0.7
0.6

λ2_IEC

0.5

Conductor size / mm2
λ2

λ2_FEM
λ2_IEC

0.4

Figure 11 Comparison of the armour loss rate λ2 between FEM
analysis and IEC equation.

90
80

×100

70
60

λ2_FEM

50

0.3

40
30

0.2

However, the larger the conductor size, the larger thedifference in the calculated λ 2 value. Figure 12 shows theresult of allowable current calculation using λ 2_IEC andλ 2_FEM for cases with a conductor size of 1,000 mm2 or
more. As shown in the figure, even in cases where a conductor size of 2,000 mm2 is required when using λ 2_IEC, aconductor size of approximately 1,700 mm 2 can be
designed using λ 2_FEM. That is, if the evaluation of λ 2_IEC isexcessive, it can be said that a more compact cable
design becomes feasible.

Conductor current / A

900

850
Calculation using
λ2_FEM
800

750

1,000

Calculation using
λ2_IEC
1,200

1,400

1,600

0

1,800

2,000

Figure 12 Difference of conductor designs depending on λ2_IEC
and λ 2_FEM.

10
0

1
2
3
Lead sheath thickness / mm

40

Figure 13 Dependence of λ 2 on the lead sheath thickness.

As described above, the results of FEM analysis haverevealed that the armour losses coefficient based on theconventionally applied IEC equation may have been overestimated, and that the thickness of the metal sheath also
has an effect to armour losses. By taking into these factors account, more accurate armour loss evaluation will
be possible, which is expected to lead to cost reductions
through optimal cable design.
The validity of the analysis results obtained here wereconfirmed by armour loss measurements using an actual
three-core submarine cable, we will report details at alater date.

5.

Conductor size / mm2

20

0.1

λ2_FEM /λ2_IEC ×100 / %Using this model, the armour losses were evaluatedwhen changing the conductor size, which is an important
cable design parameter. And armour losses are
expressed as λ 2 (armour loss rate: the ratio of armour
losses to conductor loss) in the IEC standard, therefore it
is also evaluated using λ 2 in this study. Figure 11 shows
the change in λ 2 depending on the conductor size
obtained by the analysis. Here, the value obtained by theIEC equation is indicated as λ 2_IEC, and the value obtainedby analysis as λ 2_FEM. λ 2_FEM /λ 2_IEC is also indicated as theirratio. As shown in the figure, λ 2_FEM has a smaller value
than λ 2_IEC in any conductor sizes, and the ratio was about
60-70%, which was almost constant regardless of the
conductor size.

CONCLUSION

Examples of the application of scientific calculations to
the design and development of power cable systems
were introduced.
At present, the computer ability has become very high,
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Contribution to R&D of Power Cable Systems by Applying Computer Simulationand it is possible to perform highly accurate electromagnetic field analysis and advanced simulations that were
not possible a decade ago. It contributes to the development of cable systems in a wide range of fields from thematerial development at the molecular level to the analysis of explosive phenomena. In this way, by incorporating
scientific calculations into the development of power
cable systems, which has conventionally been performedon an experimental basis, it would be understood thathave made product development more efficient.
Although not described in this paper, there are dedicated simulation software (for example, OrcaFlex) for
dynamic analysis on marine systems in the marine field,
and in Europe, they are generally adopted as tools formarine system design and are becoming standard. It is
the reason why difficult to construct an experimental
model due to the complexity of ocean phenomena, letalone actual-scale verification in the ocean. In offshore
wind power research in Japan, marine system simulation
software has begun to be applied to behavior analysis
of cables connected to wind turbines and cable laying
analysis.
Finally, in order to correctly understand the essence ofissues, experiments with actual products will not disappear. However as industrial products become larger andmore complex, product development using CAE or simulation technology will be essential. By combining themand promoting efficient product developments, we willachieve our 2025 mid-term plan, and also contribute tosociety by reducing costs and shortening the development period as well through technological development in
the relevant field.

REFERENCES
1) T.Takada, T. Tohmine, Y. Tanaka, and J. Li: Space Charge
Accumulation in Double-Layer Dielectric Systems – Measurement
Methods and Quantum Chemical Calculations, IEEE EIMagazine, Vol. 35, No. 5 (2019), 36-46.
2) N. Shigemori, M. Yagi, and T. Tabuchi: Development of 350 kV
and 525 kV HVDC extruded cable system, Jicable’19, (2019),
A9-5.
3) Home page of Furukawa Electric > News release> Long-term load
testing of DC 525kV class cable system completed. (Date of reference: December 14th, 2022)
		https://www.furukawa.co.jp/release/2021/ene_20210430.html(in Japanese)
4) Mark L.Wilkins: Computer simulation of dynamic phenomena,
Springer, 2009.
5) IEC 60287-1-1, 2006, Electric cables-Calculation of the current rating-Part 1-1: Current rating equations (100% load factor) and calculation of losses-General.
6) J.J. Bremnes: “Power loss and inductance of steel armoured
multi-core cables: comparison of IEC values with “2,5D” FEA
results and measurements”, Cigre 2010, 2020, B1-116.
7) Y. Matsumoto, et al., “3D FEM analysis of armour loss in threecore submarine cables”, Jicable’19, (2019), C8-1.

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