High voltage
cables with insulation of cross-linked polyethylene
ADVANTAGES OF PE-X CABLES
FKS's HIGH VOLTAGE CABLES WITH INSULATION OF CROSS-LINKED POLYETHYLENE OFFER MORE
ADVANTAGES THAN CONVENTIONAL PAPER-INSULATED OIL-FILLED CABLES
THE MAIN REASONS FOR USING HIGH VOLTAGE CABLES WITH INSULATION OF CROSS-LINKED
POLYETHYLENE INSTEAD OF HIGH VOLTAGE CONVENTIONAL PAPER-INSULATED OIL-FILLED CABLE ARE:
1. Low dielectric loss (tngd )
The tngd insulation of cross-linked polyethylene is not
larger than 4x10-4 and is about ten times smaller than the tngd insulation of conventional paper oil-filled cables (ranging about
3x10-3)
2. Low dielectric constant (e r)
The e r, of insulation of
cross-linked polyethylene is 2,3 and insulaton of paper oil-filled 3,7
3. High current load
The excellent electrical and thermal-physical characteristics of cables with insulation
of cross-linked polyethylene enable them to display greater continuous emergency and
current carrying capacity cables with insulation of conventional paper-insulated
oil-filled cables
| |
PE-X |
PE |
paper-insulation
oil-filled |
| Continuous
load |
90 |
70 |
85 |
| Emergency
load |
130 |
110 |
120 |
| Short-circuit rating |
250 |
150 |
160-220 |
Thermal resistivities of polyethylene and cross-linked
polyethylene are 3,5 Km/W and paper-insulated oil-filled is 5,5-6,5 Km/W.
The excellent thermo-physical properties of cross-linked
polyethylene cables enable them to display greater continuous emergency and short-circuit
carrying load than paper-insulated oil-filled cables.
4. Easy installation and accessories
5. Low weight
6. No maintenance needed
Cables with insulation of cross-liriked
polyethylene are maintenance-free as follows:
- Do not require spare amounts of highly
inflammable cable oil
- Do not require to train and maintain a team of
operation and joing personnal for oil duties such as oil-filled cables demand
- Do not require to purchase a cable oil
treatment plant
CHARACTERISTICS OF PE-X CABLES PRODUCE BY FKS's
DRY-CURING PROCESS
1. Very smooth, good contact between the
insulation and conductor screen and between the insulation and insulation screen
2. Very high performance eliminating
contaminants in insulation by adopting our Super Clean Material Supplying System
3. Completely circular insulation,
conductor screen and insulation screen without eccentricity results from using a special
crosshead and vertical continuous curing system
4. Excellent electrical characteristics
through dry curing in producing the insulation layers (insulation, conductor screen and
insulation screen)
CHARACTERISTICS OF CROSS-LINKED POLYETHYLENE FOR
HIGH VOLTAGE CABLES
THE NEW GENERATION OF THE CROSS-LINKED POLYETHYLENE
OFFERS TREE RETARDANT INSULATION COMPOUND, OZONE RESISTANCE, AS WELL AS OUTSTANDING
STABILITY AND RESISTANCE TO HEAT
Comparation of properties between cross-linked
polyethylene (PE-X), polyethylene and paper-insulation oil-filled
| |
PE-X |
pE |
paper-insulation
oil-filled |
| Dielectric strenght; kV/mm |
>40C° |
>40C° |
>40 |
| Dielectric constant |
2,3 |
2,3 |
3,7 |
| Dielectric loss; (tngd) |
<4x10-4 |
<4x10-4 |
<3x10-3 |
| Volume resistivity; W cm |
~ 1018 |
~ 1018 |
~ 1018 |
| Tensile strength; MPa |
>14 |
>14 |
- |
| Elongation at break; % |
>400 |
>400 |
- |
| Maximum operating temperature;
°C |
90 |
70 |
85 |
| Maximum short-circuit
temperature; °C |
250 |
150 |
160-220 |
| Thermal resistivity; Km/W |
3,5 |
3,5 |
5,5-6,5 |
| Specific gravity; kg/m3 |
920 |
920 |
920 |
| Heat deformation |
fine |
fairly good |
- |
| Ozone resistivity |
fine |
fine |
fine |
| Oil resistivity |
excellent |
excellent |
- |
| Weather resistance |
good |
good |
bad |
INSTALLATION OF
PE-X CABLES MINIMUM BENDING RADIUS
To ensure safe installation without damaging the electrical and physical properties of
PE-X cables, the following minimum bending radius must be preserved
| |
Copper Wire or
Tape-shielded Cable |
Metallic-sheathed
Cable |
Minimum
bending
radius after
installation (mm) |
10 Dk |
15 Dk |
Minimum
bending
radius during
installation (mm) |
20 Dk |
25 Dk |
Dk - outside
diameter of cables (mm)
PERMISSIBLE MAXIMUM PULLING TENSION
To ensure installation without damaging the electrical and physical properties of PE-X
cables, the following permissible maximum pulling tension should never exceed
Material of
conductor |
Permissible
maximum pulling tension
(kg) |
| Copper |
(5-7)*xS |
| Aluminium |
(3-4,5)*xS |
S-cross sectional area of
conductor, sqmm
*-it depends on construction of cables
SIDE WALL PRESSURE TO CABLES
Permissible maximum side wall pressure to cables (F) at
bending point during installation must be 500 kg/m (for single core cable)
| F =T/R F - Side wall pressure to cable (kg/m)
T - Pulling tension (kg)
R - Bending radius (m) |
 |
WATERPROOFTREATMENT
Water has a very harmful effect on the
electrical performance of PE-X cables. Customers are strongly advised to take special care
in avoiding water from penetrating the cable in transporting, storing, terminating and
joining of cables. Waterproof treatment is the key factor in trouble-free operation of
PE-X cables.
HV CABLES
CURRENT CARRYING CAPACITY
The calculations of the continuous current rating of cables have been made in
accordance with the recommendations in IEC Publication 287 / 1982 and the following
conditions:
- Maximum continuous conductor temperature 90 degC
- Ambient temperature for installation in air 25 degC
- Ambient temperature for installation in ground 15 degC
- Depth of laying 1000 mm
- Thermal resistivity of soil 1 .2 Km/W
- Screens bonded at both ends
For specific laying conditions and different cable constructions the information
required includes the following:
- System voltage (nominal and rnaximum)
- Rated frequency
- Type of earthing
- Maximum rated current
- Fault level and duration
- Impulse level
- Air temperature (minimum, maximum and average)
- Soil temperature (minimum, maximum and average)
- Thermal resistivity of soil
- Route lenght
- Terminating requirements
- Site limitations
Cable types:
(also available at 69, 132 and 150 kV)
| XHE 48 (-A) |
110 kV |
Aluminium or copper conductor, cross linked polyethulene
insulation, copper screen and polyethilene outersheath |
| XHE 49 (-A) |
110
kV |
Aluminium or copper conductor, cross
linked polyethulene insulation, copper screen in sandwich of swellable tapes, aluminium
copolymer tail, polyethylene outersheath |
| XHO 03 (-A) |
110
kV |
Aluminium or copper conductor, cross
linked polyethulene insulation, lead screen and polyethilene outersheath |
|
