Thursday, December 10, 2009

INSULATION

1.      SEMI CONDUCTING LAYER

This item specially for medium voltage and high voltage cables which are include:

a.          Semi Conducting Separator Tape
b.         Semi Conducting compound for Conductor Screen or Inner Semi Conducting Layer
c.          Semi Conducting compound for Insulation Screen or Outer Semi Conducting Layer


Low voltage cables need not semi conducting layer for insulation part as a general purpose except for special requirement from customer.


Table
2.1
Rev.
0
… up to 1000 volt
Voksel have almost never been used separator tape, except in special case or requirement as below;
Cable name : CU/XLPE/CWS/PVC 3x25 mm² (Midland Cable)
Material      : Polyester tape 0.025 mm for separator tape.
1001 up to 33000 volt
Size          : 35 up to 400 mm²
Material    : HFDA-0586BK55 (UCC), LE0592 (Borealis), Pramkor1001 (Korea)
Method     : Extruding (Triple processing for CCV Line I and Tandem processing for CCV Line II)
Thickness : Nom 0.7 mm, Min 0.5 mm, Max 1.2 mm (Minimum value used for internal definition if no customer request)






Graph of maximum thickness of inner semi conducting layer (conductor screen) for medium voltage cable,

 


Table
2.2 (Inner Semi Conducting Material Characteristics)
Rev.
Material certificate and catalogue
Items
HFDA-0586BK55
UCC-USA
LE0592
Borealis - Sweden
Pramkor 1001
Rak San – Korea
Physical foam
Granules
Granules
Pelet
Density
1.138~1.139 g/cm3
1.139~1.143 g/cm3
1.10~1.15 g/cm3
Tensile strength before aging
15.3~16.2 psi
21.6 N/mm²
Min. 12.5 N/mm²
Elongation after aging
182~196 %
200 %
Min. 150 %
Retention of tensile strength after aging
N/A
< 20 % (135°Cx240h)
Min. 85 % (121°Cx168h)
Retention of elongation after aging
N/A
N/A
Min. 80 %
DC volume resistivity
7~13 W.cm
6~7 W.cm
Max. 5.0 W.cm
Heat deformation
0 %
0 %
Max. 25 %
Brittleness temperature
-55 °C
N/A
Max. –10°C,
No crack
Moisture content
N/A
100~106 ppm
Max. 3000 ppm
Elastograph value
N/A
1.24~1.26 Nm
N/A
Rheometer MDR 182C 0.5 arc
10.79~11.30 in-lb
52~72 dNm
N/A







2.      INSULATION


Table
2.3 (General description for insulation)
Rev.
0
Material
Applied voltage (kV)
Temperature (°C)
Standard reference
Usage
PVC
Up to 1
70
SPLN
LV
1 to 3
70
IEC
MV
PE
Up to 400
80
JIS
LV
1 to 3
80 or 90
IEC
LV and MV
XLPE
Up to 500
90
SPLN
LV and MV
Up to 36
90
IEC
LV and MV


Table
2.4 (Max conductor temperature for different types of insulation compound)
Rev.
0
Ref.
IEC 60502
Insulating compound
Max conductor temperature (°C)
Normal operation
Short circuit (5 second duration)
PVC/B
70
160
Conductor cross section £ 300 mm²

70
140
Conductor cross section > 300 mm²
XLPE
90
250





Table
2.5 (PVC specification)
Rev.
0
Ref.
SPLN 41-2:91
Material Code
Usage
U0/U
Max temperature conductor normal condition (°C)
Without aging
Min tensile strength (N/mm²)
Min elongation (%)
INSULATION
YJ/A
Fixed installation
£ 1.8/3 kV
70
12.5
150
YJ/B
Fixed installation
> 1.8/3 kV
70
12.5
125
YJ/C
Fixed installation for inner-double
£ 450/750 V
70
12.5
125
YJ/D
Flexible cable
£ 450/750 V
70
10.0
150
YJ/E
Heat resistance for inner wires
£ 450/750 V
105
12.5
125
SHEATHING
YM/1
Fixed installation

80
12.5
150
YM/2
Fixed installation

90
12.5
150
YM/4
Fixed installation for inner-double

70
12.5
125
YM/5
Flexible cable

70
10.0
150





Table
2.6 (PE specification)
Rev.
0
Ref.
SPLN 41-11:92
Material Code
Usage
U0/U
Max temperature conductor normal condition (°C)
Without aging
Min tensile strength (N/mm²)
Min elongation (%)
INSULATION
2YJ
Fixed installation

70
10.0
300
2YJ/HD
Fixed installation high density

80
12.5
350
SHEATHING
2 YM/3
Fixed installation

80
10.0
300
2YM/4
Fixed installation

90
12.5
300



Table
2.7 (XLPE specification)
Rev.
0
Ref.
SPLN 41-9:86
Material Code
Usage
U0/U
Max temperature conductor normal condition (°C)
Without aging
Min tensile strength (N/mm²)
Min elongation (%)
INSULATION
2X
Fixed installation
1 to 30 kV
90
12.5
200






Table
2.8 (Insulation & Sheathing material purpose)
Rev.
0
MATERIAL CODE
SUPPLIER
PURPOSE
PVC for Insulation
ND 301 AAIS FLX
PT Nugratama
Flexible cable
ND IS 70 C
PT Nugratama
Insulation 70°C
SUPER IS AV
PT Nugratama
Insulation 90°C
IL 90
PT Setia Pratama Lestari
Insulation 90°C
IL YJ/A BK
PT Setia Pratama Lestari
Insulation 90°C
PVC for Sheathing
ND SL 90 C
PT Nugratama
LV sheathing 90°C
ND SL 70 C FRC LS
PT Nugratama
LV sheathing 70°C (flame retardant)
ND SL 90 AT
PT Nugratama
LV sheathing 90°C (anti termite)
ND SL 90 OIL
PT Nugratama
LV sheathing 90°C (oil resistance)
ND SL 70 C
PT Nugratama
MV sheathing 70°C
ND SL 90 YM 5
PT Nugratama
MV sheathing 90°C
PVC for Filler
F 8888
PT Nugratama
Filler
XLPE Insulation for Low Voltage
XLPE Maslink Compound
Satya Wirya
Natural
XLPE Bojong LV 1000
PT Bojong Westplas
Natural
XLPE SL 1230NT/MB
LG Chem (Korea)

DFDW-5451 NT SI-LINK
UCC (USA)

IFDB-5480 NT SI-LINK
UCC (USA)

XLPE 9802
PT Setia Pratama Lestari

XLPE Insulation for Medium Voltage
XLPE HFDJ-4201
NUC

XLPE NUCV-9517
NUC
XLPE electrical tracking
HFDA-0217 BK
UCC (France)

HFDG-4201 NT
UCC (France)

HFDE-4201 NT
Penta Niaga

XL 4201 RBE
Borealis









INSULATION THICKNESS


Table
2.9 (PVC insulation thickness for Low Voltage)
Rev.
0
Ref.
IEC 60502-1:97
SPLN
Cross section area (mm²)
Thickness (mm)
Nom thickness (mm)
Min
Nom
Max
0.6/1 (1.2) kV
1.8/3 (3.6) kV
1.5 & 2.5
0.62
0.8
0.98
0.7
-
4 & 6
0.80
1.0
1.20
0.7
-
10 & 16
0.80
1.0
1.20
0.7
2.0
25 & 35
0.98
1.2
1.42
0.9
2.0
50
1.16
1.4
1.64
1.0
2.0
70
1.16
1.4
1.64
1.1
2.0
95
1.34
1.6
1.86
1.1
2.0
120
1.34
1.6
1.86
1.2
2.0
150
1.52
1.8
2.08
1.4
2.0
185
1.70
2.0
2.30
1.6
2.0
240
1.88
2.2
2.52
1.7
2.0
300
2.06
2.4
2.74
1.8
2.0
400
2.24
2.6
2.96
2.0
2.0
500
2.42
2.8
3.18
2.2
2.2
630
2.42
2.8
3.18
2.4
2.4
800
2.42
2.8
3.18
2.6
2.6
1000
2.60
3.0
3.40
2.8
2.8










Table
2.10 (XLPE insulation thickness for medium voltage)
Rev.
0
Ref.
IEC 60502-2 & SPLN 43-5
Rated voltage
(kV)
Size
(mm²)
Nom thickness
(mm)
6/10 (12)
16 to 1000
3.4
8.7/15 (17.5)
25 to 1000
4.5
12/20 (24)
35 to 1000
5.5
18/30 (36)
50 to 1000
8.0
Ref.
SPLN 43-5
1.8/3 (3.6
10 to 400
2.0
500
2.2
630
2.4
800
2.6
1000
2.8
Ref.
IEC 60502-2 & SPLN 43-5
3.6/6 (7.2)
10 to 185
2.5
240
2.6
300
2.8
400
3.0
500 to 1000
3.2










How to design the insulation thickness in general method (special case for high voltage)

1.        AC voltage method
2.        Impulse voltage method


1.        AC VOLTAGE METHOD

 



             

E              : normal voltage (kV)
L1            : temperature coefficient     (1.1)
                              10% breakdown voltage drop of temperature rise by current (90°C for XLPE)
L2            : aging coefficient                (4.0)       
                              400% voltage drop after some years using of cable
L3             : safety coefficient               (1.1) 
ELAC        : min average electric field strength breakdown voltage (kV/mm)
                                 

  See at table 025

Table
2.11
Rev.
0
Ref.
SWCC
ITEM
kV
66
77
154
275
E/Ö3
kV
39.9
39.9
46.5
46.5
93.0
166

kV
195
195
225
225
455
805
ELAC
kV/mm
35
35
30
30
20
30
tAC
kV
5.5
5.5
11.3
7.5
22.8
26.9
BIL
kV
350
350
400
400
750
1050

kV
535
535
610
610
1140
1600
Eimp
kV/mm
50
70
50
60
50
60
timp
mm
10.7
7.6
12.2
10.1
22.8
26.7

mm
11
9
13
11
23
27


In case of 30 kV, max applied voltage in actual with current condition as followed;






2.        IMPULSE VOLTAGE METHOD






BIL          : breakdown impulse level in actual cable circuit
k1             : temperature coefficient     (1.25)
k2             : aging coefficient                (1.1)
k3             : safety coefficient               (1.1)
Eimp         : min electric field strength breakdown voltage for impulse (kV/mm)












Table
2.12
Rev.
0
Rated voltage
Particles
Amber
Up to 33 kV
< 100 mm
< 170 mm
34 to 275 kV
< 100 mm
< 100 mm





For 66 kV XLPE cables and above (example 66.77 kV)

Table
2.13
Rev.
0
1
Void
< 70 mm
2
Black
< 100 mm
3
Amber
< 250 mm
4
Metal
< 100 mm
5
Protuberance
< 250 mm


1.        VOID

As seen an air hole in insulation space.
If the void diameter more than 70mm, water tree cases are possibility to occur.





2.        BLACK

PE material remainder on screw surface and stay for a long time period, then become to a carbon have conductivity itself, it called Black.





3.        AMBER

Change colour of insulation (turn yellow not on all of insulation surface), the phenomena same as Black cases, but Amber not remain in a long time period on screw. It could be occurred in over time processing without any stop.


4.        METAL
The metal have conductivity issued to be most critical material for XLPE. For one case metal come into XLPE when the mesh broken by increasing pressure.






5.        PROTUBERANCE
Some insulation materials usually have a protuberance (or stick out) by some causes, moisture, semi conducting material, or shape of conductor.





Drying (for more than 66 kV XLPE cables)

In cross-linked processing, some portion in cable could be leaved behind chemicals additives beside XLPE. For an example, H2O formed in cross-linked reaction can be leaved behind in the cables with other layers (such as tape, sheath or etc.). For plain cables (insulated conductor) H2O can be natural vaporized in air.
In fact, water tree cases could be occurred by the phenomena.
For less than 33 kV, insulation need more drying process, depend on the thickness. Thicker insulation will need more drying process.


3.       OUTER SEMI CONDUCTING LAYER

Construction for up to 33 kV for generally, semi conducting tape applied over the extruding layer.
028




















Table
029 Characteristic of Semi Conductive Tape
Rev.
0
Construction
Code name
Characteristic of tape
Description
Unit
Ave. value
Min value
Max value
No of measurement
LANTOR
3C1131
Thickness
mm
0.28
0.27
0.28
5
Mass per unit area
g/m²
110
107
114
5
Elongation at TS
%
12
9
12
5
Volume resistivity
kW.cm
108
86
154
5
Tensile strength
N/cm
63
54
69
5
Swelling speed
mm/min
4.8
3
6
18
Swelling height
mm
6.8
6.1
7.7
18
GECA TAPES
GT 2051


Average value
Normal value
Weight
g/m²
132
120 ± 12
Thickness
mm
0.46
0.44 ± 0.07
Tensile strength
N/50mm
236.8
210 – 50
Elongation
%
15.5
19 ± 5
Swelling height
mm/3.00”
15.5
> 7
Surface resistance
W/
774
< 150












SEMI CONDUCTING TAPE


1.        Dimension           
 

D      : diameter over semi conductive tape (mm)
d       : diameter under semi conductive tape (mm)
t        : semi conductive tape thickness (mm)


2.        Weight                
 


w1            : material weight for single core (kg/km)
l1            : percentage overlap
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