Components: The steel - cored aluminum strand consists of aluminum wires and a steel core. The aluminum wires, as the main conductive part, surround the steel core. The steel core usually adopts galvanized steel wires, providing high mechanical strength for the strand.
Stranding method: The aluminum wires and the steel core usually adopt a concentric stranding method. This stranding structure enables the strand to evenly distribute the force when under tension, ensuring the stability and reliability of the cable.
Performance characteristics
Conductivity: Since aluminum has good electrical conductivity, the aluminum wires, as the main conductive material, enable the steel - cored aluminum strand to have relatively good conductive ability, which can effectively transmit electrical energy and reduce power loss. In long - distance transmission lines, this good conductive performance is particularly important and can reduce transmission costs.
Mechanical strength: The existence of the steel core greatly improves the mechanical strength of the strand. It can withstand large tensile forces. For example, in overhead transmission lines, it can resist external forces such as wind load and ice load, preventing the strand from breaking due to excessive tension. It is suitable for transmission environments with large spans and high tensions, ensuring the safe operation of transmission lines.
Corrosion resistance: The surface of the aluminum wires usually has an oxide film, and this oxide film has certain anti - corrosion ability. Meanwhile, the galvanized treatment of the steel core also enhances its anti - corrosion performance, enabling the steel - cored aluminum strand to be used for a long time under different environmental conditions, including some outdoor environments with a certain degree of corrosiveness.
Application fields
Overhead transmission lines: It is widely used in overhead transmission lines of high - voltage, extra - high - voltage, and ultra - high - voltage. In long - distance power transmission, from power plants to substations or connections between different substations, the steel - cored aluminum strand is the main choice for transmission conductors. For example, in transmission lines built under various topographical conditions such as mountainous areas and plains, it is used to transmit electrical energy from the power generation end to urban and industrial areas and other electricity - consuming centers.
Large - span transmission projects: It performs outstandingly in large - span transmission projects such as those crossing rivers and valleys. Due to its high strength and good conductive performance, it can meet the strict requirements for the mechanical and electrical properties of conductors under large - span distances, ensuring the stable operation of large - span transmission lines, such as transmission line projects crossing large rivers like the Yangtze River and the Yellow River.
Product Parameters
1. Model - specification - related parameters
Nominal cross - section: Steel - cored aluminum strands have various nominal cross - sections, such as the commonly seen 10/2, 16/3, 25/4, etc. Here, the numerator represents the nominal cross - section of the aluminum wire part (unit: mm²), and the denominator represents the nominal cross - section of the steel core. Different nominal cross - sections are applicable to different transmission capacity and voltage level requirements. Smaller cross - sections may be used for some short - distance, low - capacity distribution lines, while larger cross - sections are used for long - distance, high - capacity transmission lines.
Number of structural strands and diameter: It includes structural information of both the aluminum wire and the steel core. For example, for a certain type of steel - cored aluminum strand, there may be 6 aluminum wires with a diameter of 3.20 mm, and 1 steel core with a diameter of 2.50 mm. These parameters determine the overall size and physical properties of the strand, affecting the flexibility, weight, etc. of the strand, and are also related to its applicability under different erection conditions.
2. Electrical performance parameters
DC resistance: This is an important indicator for measuring the conductive performance of the steel - cored aluminum strand. At 20 °C, different models of steel - cored aluminum strands have their specific DC resistance values (unit: Ω/km). The smaller the DC resistance, the lower the power loss during the power transmission process. For example, the DC resistance of the LGJ - 185/30 model is approximately 0.1007 Ω/km under the specified temperature. This parameter is crucial for calculating the voltage drop and power loss of the transmission line.
Current - carrying capacity: The current - carrying capacity represents the maximum current value (unit: A) that the steel - cored aluminum strand can safely carry under specified conditions. It is affected by multiple factors such as the material of the strand, heat dissipation conditions, and ambient temperature. For example, under specific conditions such as an ambient temperature of 40 °C and a wind speed of 0.5 m/s, the current - carrying capacity of a certain type of steel - cored aluminum strand may be 445 A. Accurate current - carrying capacity data is very important for determining the transmission capacity of the transmission line and preventing the conductor from overheating.
3. Mechanical performance parameters
Calculated breaking force: The calculated breaking force is the maximum tensile force that the steel - cored aluminum strand can withstand in a tensile test (unit: N). It is a key indicator for measuring the mechanical strength of the strand and is determined by factors such as the materials of the aluminum wire and the steel core, the cross - sectional area, and the stranding process. For example, the calculated breaking force of the LGJ - 400/50 model can be around 123400 N. When designing an overhead transmission line, it is necessary to ensure that the tensile force on the strand under various meteorological conditions and load situations does not exceed its calculated breaking force to ensure the safety of the line.
Elastic modulus: The elastic modulus reflects the elastic deformation characteristics of the steel - cored aluminum strand when it is under force (unit: GPa). Strands of different materials and structures have different elastic moduli. It is of great significance for analyzing the deformation of the transmission line under dynamic loads such as wind vibration and ice load. In the mechanical analysis and design of the transmission line, the elastic modulus needs to be considered to accurately predict parameters such as the sag of the conductor.
Coefficient of linear expansion: The coefficient of linear expansion refers to the change in unit length of the steel - cored aluminum strand for every 1 °C change in temperature (unit: 1/°C). Under different climate conditions, temperature changes will cause the length of the strand to change. This parameter is crucial for calculating the sag change and tension adjustment of the line during temperature changes, helping to ensure the safe operation of the line in different seasons.
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