Oil-Filled Cable

oil-filled cable

[′ȯil ¦fild ‚kā·bəl]
(electricity)
Cable having insulation impregnated with an oil which is fluid at all operating temperatures and provided with facilities such as longitudinal ducts or channels and with reservoirs; by this means positive oil pressure can be maintained within the cable at all times, incipient voids are promptly filled during periods of expansion, and all surplus oil is adequately taken care of during periods of contraction.

Oil-Filled Cable

 

a high-voltage power cable in which the paper insulation is impregnated with mineral oil under pressure. An increase in the electric strength of insulation is achieved in oil-filled cables through the elimination of gas inclusions (voids) within the insulation, which are potential sites of breakdown, by filling them with oil. During operation of the cable the oil pressure is maintained by make-up equipment. Oil-filled cables are used to lead power lines from large power plants or underground hydroelectric power plants to distribution equipment, where power transmission lines cross water obstacles, in densely builtup areas, and where power lines extend far into cities with high power consumption.

Two types of oil-filled cable are manufactured in the USSR. The first type is a single cable with a centrally located oil channel, with the oil under low or medium pressure (0.1-0.3 meganewtons per sq m [MN/m2]). The second type is a multicore high-pressure cable (1.4-1.5 MN/m2). The first type has a conductor with a cross section of 150-800 sq mm made of tinned, shaped copper wires arranged in concentric layers. The channel diameter is usually 12 mm for cables of any cross section; it is formed by twisting the wires of one layer. The insulation of an oil-filled cable consists of oil-impregnated high-voltage cable paper (sometimes calendered); the electric strength of the oil is not less than 180 kilovolts per cm (kV/cm). The insulation is separated from the strand and the metallic sheath by a screening layer of semiconducting paper. Sometimes the outer screen is supplemented by copper or aluminum foil. The lead sheathing is usually reinforced by a hard-rolled copper ribbon. The use of aluminum sheathing substantially decreases the cost of oil-filled cable and also reduces its weight. However, the aluminum sheathing must be corrugated to make it flexible, and it also requires increased protection from corrosion. Single oil-filled cable is most frequently used for voltages from 110 to 220 kV.

In multicore high-pressure oil-filled cables the insulated, circular multiwire conductors have no inner channel; they are arranged in an oil-filled steel pipe with a diameter of 220 to 270 mm. The paper insulation and the cross sections of the strands are the same as those of single cable, but the electric strength of insulation is considerably higher than in low-pressure oil-filled cables. The steel pipe is protected on the outside by corrosion-resistant coatings. The cable is assembled directly at the cable run. The pipeline is welded together from sections; the insulated conductors are delivered from the factory in a lead sheath, which is stripped when the conductors are pulled into the pipe. After completion of the laying operations, oil is pumped through the pipeline a number of times until the desired electrical characteristics are produced. High-pressure oil-filled cables are used for voltages from 220 to 750 kV. Forced cooling of the cable is desirable for voltages above 500 kV; such cooling is achieved by circulating cooled and purified oil through the pipeline.

In the USA and Japan, and in several European countries, oil-filled three-core cables are manufactured for voltages from 60 to 110 kV, with conductor cross sections from 80 to 325 sq mm. The conductors are arranged in a straight line (flat cable) or around the circumference. Oil-filled cables are noted for their high reliability and ability to withstand prolonged overloads, as well as for the stability of the electric strength of the insulation.

REFERENCES

Privezentsev, V. A., and E. T. Larina. Silovye kabeli i vysokovol’tnye kabel’nye linii. Moscow, 1970.
Belorussov, N. I. Elektricheskie kabeli i provoda. Moscow, 1971.

V. M. TRET’IAKOV

References in periodicals archive ?
This project follows a previous contract awarded to Prysmian by the Gulf Cooperation Council Interconnection Authority (GCCIA) for a 400 kV HVAC oil-filled cable submarine interconnection between Saudi Arabia and Bahrain.
The company also is continuing a number of green initiatives and policies to reduce environmental impacts, including: Replacing some types of oil-filled cable with solid-state electrical transmission and distribution cables; Reducing methane emissions through enhanced maintenance at gas facilities; Supporting the Regional Greenhouse Gas Initiative; Installing a "green roof" atop its Learning Center in Long Island City and; Rolling out an EnergyNY program to inform New Yorkers about ways to save money and energy relative to their utility costs.
This project comes after a previous contract offered to Prysmian by the Gulf Cooperation Council Interconnection Authority (GCCIA) for a 400 kV HVAC oil-filled cable submarine interconnection between Saudi Arabia and Bahrain.
Contract notice: "Replacement of 110kV oil-filled cable line" Dragalevtsi "- an element of the critical infrastructure of the 110 kV distribution network of the city of Sofia".
Contract award notice: design replacement of oil-filled cable transmission line 110 kv "sugar factory" linear knife disconnectors 110 kv ps "orion" to the linear blade 110 kv circuit breaker in lv "borimechka" and partial reconstruction of 110 kv switchyards at two substations, ref.
Contract award notice: choosing a licensed consultant to assess the compliance of the investment project and the exercise of independent supervision for the project: "replacement of oil-filled cable transmission line to 110 kv" sugar factory "linear knife breaker to 110 kv of ps" orion "to the linear blade breaker to 110 kv in ps "borimechka" supply of materials, equipment and reconstruction of switchgear to 110 kv substations in both "ref.
Dismantling and disposal of all oil-filled cable systems.
Contract notice: Choosing a licensed consultant to assess the compliance of the investment project and the exercise of independent supervision for the project: "replacement of oil-filled cable transmission line to 110 kv" sugar factory "linear knife disconnectors 110 kv cb" orion "to a straight knife disconnectors 110 kv in lv "borimechka" supply of materials, equipment and reconstruction of 110 kv switchyards at both substations ", ref.
Contract notice: Designing the replacement of oil-filled cable transmission line 110 kv "sugar factory" linear knife disconnectors 110 kv ps "orion" to a straight knife disconnectors 110 kv ps "borimechka" and partial reconstruction of 110 kv switchyards at both substations, ref.
Delivery of oil-filled cable 1 x 630 mmA 64/110kV on 4 drums 700 metres each (total: 2 800 m) for Vattenfall Europe Netzservice GmbH, Berlin on steel drums (including the respective oil-compensating reservoir).