The yoke plate is a core mechanical connection and load distribution component in transmission lines, substations, and power fitting systems. It is typically a flat metal plate with multiple holes. Its core function is to connect insulators, U-shaped rings, bolts, tension clamps, and other components in series or parallel, evenly distributing conductor tension, wind load, and icing load, ensuring the mechanical stability of the power system under complex operating conditions. Simply put, it's like a "universal adapter" in power fittings-connecting a crossarm on one side and an insulator string on the other, distributing conductor load in the middle, making it an indispensable "stress-bearing hub" for high-voltage/ultra-high-voltage lines.
Low-carbon steel
Low-carbon steel refers to ordinary carbon steel with a carbon content ≤0.25%. Domestically, Q235 (yield strength 235MPa) is commonly used, while internationally it corresponds to SS400 and A36. It is the most basic steel material in the industrial field. With a tensile strength of 370-500MPa, it can withstand conventional line loads, is not easily brittle, and does not crack during bending and stamping. It is suitable for complex hole positions and irregular designs. Cutting, drilling, punching, and hot bending are easy, resulting in high production efficiency, low defect rate, and cost-effective small-batch customization. Main application scenarios include 10kV, 35kV, and 110kV conventional transmission lines, ordinary urban environments, conventional bay insulator connections, busbar mounting plates, hardware in non-corrosive areas, non-coastal areas, non-chemical zones, and inland areas without heavy pollution. It is a priority project for projects prioritizing cost-effectiveness.
Hot-dip galvanized high-strength carbon steel
It is the preferred heavy-duty Yoke Plate, with a carbon content of 0.18%-0.22%. The addition of small amounts of Mn and Si enhances its strength, making it less brittle than high-carbon steel. It is less prone to deformation and breakage under heavy loads, exhibits good fatigue resistance, and is less prone to cracking under long-term vibration. It is also hot-dip galvanized, providing a corrosion protection life of 20-25 years. It is more durable than ordinary low-carbon steel, but its price is 20%-40% higher than Q235. It also has higher hardness, requiring specialized molds for drilling and punching, resulting in slightly higher processing energy consumption. Applications include 220kV, 400kV, and 500kV main grid lines, long spans, areas with heavy icing, and strong winds, high-current busbar mounting plates in substations, converter station connection hardware, and wind power transmission lines.
(三)Alloy structural steel
Alloy structural steel Yoke Plate is used for ultra-high voltage/extra-high voltage and extreme heavy-load applications. Alloy structural steel is made by adding alloying elements such as Cr, Mo, Ni, and V to carbon steel, and then forging and heat-treating it to achieve ultra-high strength and toughness. Representative grades include 40Cr and 35CrMo, belonging to high-end load-bearing steel. The tensile strength of alloy structural steel is 900-1200MPa, 2-3 times that of low-carbon steel, and it can withstand ultimate loads exceeding 100kN, making it the "top-of-the-line material" for ultra-high voltage lines. It is not prone to cracking under long-term wind vibration and temperature differences (-40℃~+60℃), has good impact toughness, and is not easily broken when ice detaches or conductors gallop. Hot-dip galvanizing and passivation treatment, or Dacromet coating, provides a corrosion protection life of 25-30 years, making it suitable for extremely harsh environments. Alloy structural steel Yoke Plates are mainly used in ±800kV UHVDC and 1000kV UHVAC lines, as well as three- or four-string insulator connecting plates and large-tonnage tension plates.
(四)aluminum alloy
Aluminum alloys are based on aluminum, with added elements such as Mg, Si, and Cu. Commonly used grades include 6061 (T6 heat treatment) and 6063. Their density is only one-third that of steel, making them lightweight metal materials. With a density of 2.7 g/cm³ (steel 7.85 g/cm³), they reduce weight by 60% for the same dimensions. High-altitude installation (tower work) requires no large equipment and can be done manually, reducing the risk of falls. A dense alumina film forms on the aluminum surface, isolating air and moisture, eliminating the need for hot-dip galvanizing. They have a lifespan of 20-25 years in coastal areas, chemical industrial zones, and high-humidity environments, without rust concerns. This Yoke Plate is mainly used in 10kV and 35kV low-voltage power distribution lines, suitable for short spans, non-icing environments, and ordinary urban environments.
(五)Stainless steel
Stainless steel contains ≥10.5% chromium. 304 (18-8 stainless steel, 18% chromium, 8% nickel) is a general-purpose grade, while 316 (with 2%-3% molybdenum) offers superior resistance to acids, alkalis, and salt spray, making it a high-end anti-corrosion metal. 304 is resistant to ordinary corrosion, while 316 is resistant to salt spray, acids, alkalis, and seawater. It has a service life of over 30 years in coastal areas, chemical plants, and offshore platforms, and will never rust. Its tensile strength is 510-620MPa, close to Q235, providing impact and fatigue resistance, making it suitable for medium loads and vibration environments. It has a long-lasting metallic luster, requires no coating, and is easy to wipe clean of oil and dust, making it suitable for clean areas and outdoor landscape lines. It is applicable to coastal offshore wind farms, cross-sea transmission lines, chemical industrial park substations, seawater desalination plant power systems, offshore platforms, and port terminal power supply lines. For long-term exposure to seawater and salt spray, stainless steel is the only long-term solution.
Yoke Plate may seem simple, but in reality, "material determines lifespan, and craftsmanship determines safety." Choosing the right material can make electrical fittings maintenance-free for 20-30 years, avoiding power outages; choosing the wrong material may result in rust and replacement every 1-2 years, or even breakage leading to major safety accidents.
