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Aluminium conductor steel-reinforced cable (ACSR) is a type of high-capacity, high-strength stranded conductor typically used in overhead power lines. The outer strands are high-purity aluminium , chosen for its good conductivity, low weight, low cost, resistance to corrosion and decent mechanical stress resistance.
The equation in section 310-15(C) of the National Electrical Code, called the Neher–McGrath equation (NM), may be used to estimate the effective ampacity of a cable: [3] = (+) (+), In the equation, T c {\textstyle T_{c}} is normally the limiting conductor temperature derived from the insulation or tensile strength limitations.
Its light weight and softness result in roughly 30% greater conductivity than an equivalent ACSR conductor, allowing 14% more current to be carried at equal temperature. For example, 1.107 in (28.1 mm) diameter ACCC "Drake" conductor at 75 °C has an AC resistance of 106 mΩ/mile, [ 7 ] while equivalent ACSR conductor has an AC resistance of ...
The carbon core conductor's reduced thermal sag allows it to carry up to twice the current ("ampacity") compared to all-aluminum conductor (AAC) or ACSR. The power lines and their surroundings must be maintained by linemen , sometimes assisted by helicopters with pressure washers or circular saws which may work three times faster.
They are based on "steady-state (equilibrium) ampacity" calculations. Emergency ratings are based on transient equations and models: they provide permissible overload ratings for a short and adjustable time (typically 5 to 30 minutes). Forecasting methods have been developed to determine intraday and day-ahead ampacity forecasts.
For example, the United States National Electrical Code, Table 310.15(B)(16), specifies that up to three 8 AWG copper wires having a common insulating material (THWN) in a raceway, cable, or direct burial has an ampacity of 50 A when the ambient air is 30 °C, the conductor surface temperature allowed to be 75 °C. A single insulated conductor ...
The formula to calculate the area in circular mil for any given AWG (American Wire Gauge) size is as follows.represents the area of number AWG. = (() /) For example, a number 12 gauge wire would use =:
IEC 60364 Electrical Installations for Buildings is the International Electrotechnical Commission (IEC)'s international standard on electrical installations of buildings.This standard is an attempt to harmonize national wiring standards in an IEC standard and is published in the European Union by CENELEC as "HD 60364".