400 KV PPLP-Insulated Oil-Filled Cables For Power Grid
400 KV PPLP-Insulated Oil-Filled Cables For Power Grid
400 KV PPLP-Insulated Oil-Filled Cables For Power Grid
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〔1〕INTRODUCTION
PowerGrid Ltd. is developing a new 400 kV transmission
network to deliver electric power from the western end of the
island to downtown Singapore, as shown in Fig. 1. Hitachi
Cable, Ltd. was awarded the contract in conjunction with a
Japanese cable manufacturer for construction of 400 kV Ayer Rajah
400kV Transmission
Substation
underground cable system to be installed between the Ayer Line
Rajah Substation and the Labrador Substation in the
transmission network. The awarded transmission line consists Tuas Power
of one circuit of 400 kV oil-filled cables and its route length is Station Labrador
Substation
approximately 4 km. The required transmission capacity for the
circuit is 1000 MVA. The design of the power cable is 2000 Fig. 1−New 400 kV transmission line
Hitachi Cable, Ltd. was awarded the contract for one circuit of the
mm 2 six-segmental copper conductor, PPLP-insulated,
400 kV transmission line between Ayer Rajah Substation and
aluminum sheathed and MDPE jacketed oil-filled cable. PPLP, Labrador Substation.
which can reduce the dielectric loss and insulation thickness in
comparison with conventional Kraft paper, was adopted for the design, the cable and its accessories, type approval tests and
cable insulation. The power cable and its accessories were installation work of the cable system.
subjected to type approval tests generally in accordance with
IEC 141-1. The entire length of the power cables and auxiliary
cables was installed in a reinforced concrete trough providing 〔2〕SYSTEM DESIGN
protection against external damage. The schematic diagram of the 400 kV oil-filled cable
This paper describes the main features of the system system is shown in Fig. 2. The 4 km long cable route is divided
11 10
1 3 4
14 15
5
12 13
1 400 kV PPLP-insulated oil-filled cable 2 SF6 gas immersed type sealing end 3 Insulated joint
4 Straight joint 5 Oil stop joint 6 Overground oil reservoir
7 Underground oil reservoir 8 Pressure gauge panel (3 way) 9 Pressure gauge panel (6 way)
10 Oil feeding pipe 11 Insulating connector 12 Link box for earthing
13 Link box for cross bonding 14 Bonding lead 15 Concentric bonding lead
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Fig. 4−Dimension and
1 Joint casing
;
4 Oil impregnated paper
2 Insulating flange
5 Connector
3 Earthing terminal
6 Epoxy bell mouth
construction of oil
stop joint
Epoxy stop unit type oil
stop joint was applied as
compact-type.
7 Ferrule 8 Epoxy stop unit 9 Shield electrode
TABLE 2 MAIN ITEMS AND CRITERIA OF TYPE the oil stop joint simulating the actual installation.
APPROVAL TESTS All the tests were successfully completed. The measured
400 kV oil-filled cable and accessories were subjected to type values of dielectric loss angle were stable before, during and
approval tests generally in accordance with IEC141-1. after loading cycle test and did not show any progressive
increase.
Item Test criteria
Bending test 4m Dia. × 3 cycles
High voltage time test AC 520 kV/24h 〔5〕INSTALLATION
Lightning impulse test ±1550 kV/10 shots
Switching impulse test ±1175 kV/10 shots
The power cables and auxiliary cables were installed in a
AC voltage test AC 415 kV/15 min. reinforced concrete trench to protect them against external
Maximum dielectric loss angle damage. A typical cross section of reinforced concrete trench is
0.1% at 121 kV, 242 kV and 323 kV shown in Fig. 6. The buried depth of the cables below ground
Dielectric loss angle test 0.12% at 402 kV
Maximum dielectric loss angle difference
0. 025% between 242 kV and 402 kV Ground level
Dielectric loss angle/ Max. 0.1% at ambient temperature, 40˚C,
temperature test 60˚C and 85˚C
Loading cycle: 20 cycles (8 h on/16 h off)
Conductor temperature: 95∼100˚C
Reinforced concrete cover
1500
Test bushing
1050kV A.C.Tr.
Naohisa Numata
Senior Engineer
Power Cable Accessories & Distribution System
Dept., Hitaka Works.
Currently engaged in design of EHV cable
accessories.
Received B.E. degree in Electrical Engineering from
Ibaraki University in 1981.
Member of the IEE of Japan.
Hideaki Nagano
Senior Engineer
Tokyo Power Cable Construction Center
Currently engaged in overall management on power
cable construction projects in the Tokyo metropolitan
area.
Graduated with a degree in Electrical Engineering
Fig. 8−Pipe jacking work from Hakodate National College of Technology in
Pipe jacking method was adopted for crossing the highway. 1975.