power cable

(redirected from MC cable)
Also found in: Dictionary, Thesaurus.
Related to MC cable: BX cable

power cable

A metal wire that provides electricity to a unit of equipment. Contrast with "signal cable," which is used to transfer data. See molex connector.

Power Cable

 

an electric cable designed to transmit electric power from the place where it is produced or converted to industrial enterprises, stationary power and lighting installations, transportation installations, and public utilities. The term “power cable” in the generally accepted sense refers to cables designed to carry voltages up to 35 kilovolts (kV), usually with paper insulation impregnated with a viscous insulating compound. A cable with oil under pressure is used for higher voltages (seeOIL-FILLED CABLE).

The most extensively used power cables are designed to carry voltages up to 10 kV. They contain three aluminum or, less often, copper sector-shaped conductors, with a cross section up to 240 sq mm. The primary insulation on such power cables consists of paper tapes applied in a spiral around each conductor; the tapes are impregnated with a viscous insulating compound of 75 to 85 percent mineral oil and 15 to 25 percent rosin. The thickness of the insulation around each conductor depends on the nominal voltage of the cable and varies from 0.75 mm for 1 kV to 2.75 mm for 10 kV. The insulated conductors are twisted together and surrounded by an insulating paper covering approximately half the thickness of the insulation around each conductor. An airtight metal sheath made of lead or aluminum (the latter material is becoming predominant) is pressed onto the paper covering, followed by a protective jacket.

Power cables designed to carry voltages of 20 to 35 kV have round conductors with individual insulation up to 9 mm thick. Each conductor has an individual metal sheath or a covering made of metal foil.

In the operating temperature range of 50° to 80°C, the viscosity of the oil-rosin compound is lowered. As a result, on inclined portions of a power cable run the uppermost parts of the cable can become unserviceable because of the gradual flow of the liquid insulation. Therefore, the difference between the heights of the upper and lower points in a cable run is strictly limited to maximum permissible values of 5 to 25 m for cables carrying voltages of 35 to 1 kV, respectively.

One of the principal trends in improving power cables is the expansion of the output of cables having a nonflowing impregnating compound, which permit cable runs with steeply inclined and vertical segments. Another trend is the changeover from paper insulation to insulation made from polymers, such as polyvinyl chloride and polyethylene. The use of improved types of insulation results in significant savings in deficient paper, oils, and rosin and reduces labor expenditures and production time. The use of such insulation materials makes cables lighter and increases the permissible operating temperature. For example, a power cable with insulation made of cross-linked polyethylene maintains a high resistance to deformations even at temperatures up to 150°C over a limited time. This property is very important during short circuits.

REFERENCES

Privezentsev, V. A., and E. T. Larina. Silovye kabeli i vysokovol’tnye kabel’nye linii. Moscow, 1970.
Belorussov, N. I. Elektricheskie kabeli iprovoda. Moscow, 1971.
Barnes, C. Silovye kabeli. Moscow, 1971. (Translated from English.)

V. M. TRET’IAKOV

power cable

An assembly of one or more electric conductors with one or more of the following protective coverings: insulation, inner jacket, protective armor, and outer jacket.
References in periodicals archive ?
The main difference between MC cable and FMC is that FMC doesn't have the insulated wires preinstalled; you have to pull them through instead.
If you just have one or two cuts to make and don't want to invest $30 in a cutting tool, bend the MC cable sharply until the armor pops open, and then use that opening to start the cut with a side/diagonal cutter.
Cutting the armor without damaging the wires is probably the trickiest part of working with MC cable.
Connectors like the one shown here (Speed-Lock is one well-known brand) are popular with electricians because the one screw secures both the connector to the box and the MC cable to the connector.
MC cable is identified by the gauge of the wire, not the diameter of the armor.
These MC cables eliminate the need for conduit and should make the installation of large arrays simple and fast.