The technical parameters of 3-Hole Connecting Yoke Plates must be 100% compatible with the project's line grade, conductor split number, load requirements, and installation space. Pay particular attention to the following specific characteristic parameters to avoid installation failures or safety hazards due to parameter mismatches.
Hole Distribution and Dimensions: Clearly define whether it's a triangular or linear distribution. A triangular distribution is suitable for high-voltage lines with three-split conductors, while a linear distribution is suitable for the confined spaces of substations. For a triangular distribution, the side length tolerance should be ≤1mm, the hole center distance tolerance ±0.5mm, and the equilateral error ≤1mm. For a linear distribution, the hole center distance tolerance should be ±0.5mm, and the linearity error of the three sets of holes ≤0.5mm. The hole diameter and customer bolt fit accuracy (H12/h11 recommended), the thickness of the inner wall protective layer (≥100μm, detectable with a thickness gauge), and the hole edge chamfer (R≥2mm, to prevent stress concentration) are also important.
The mechanical properties of 3-Hole Connecting Yoke Plates are also a key concern. The rated breaking load must be 1.5 times higher than the actual project requirements, and in corrosive environments, the load must be increased by one level. The thickness of the three-hole yoke plate must be 20% thicker than that of the two-hole yoke plate. For frame structures, the cross-sectional dimensions and overall rigidity of the frame must be checked to avoid strength reduction caused by multiple sets of holes. For UHV and long-span line projects, fatigue test reports must be verified.
When manufacturing 3-Hole Connecting Yoke Plates, Q345B high-strength low-alloy steel is typically preferred. For strictly corrosive environments, ductile iron is used, and the stainless steel must be clearly specified as either 304 or 316. Surface treatment processes are selected based on the corrosion level, and corresponding verification and testing reports are mandatory.
Normal Environment: Thickened hot-dip galvanized (≥120μm), salt spray test ≥144h;
Corrosive Environment: Dacromet treatment, salt spray test ≥500h;
Extreme Environment: 316 stainless steel, no surface treatment, material certificate provided.
The application scenarios for 3-Hole Connecting Yoke Plates are specialized. During procurement, the voltage level, corrosive environment, and installation location of the project must be considered to verify the product's compatibility and avoid using oversized or undersized materials.
330kV and below: Linearly distributed flat three-hole mounting plates are acceptable, with a rated breaking load of 120kN;
330kV~750kV: Triangularly distributed frame-type three-hole mounting plates are mandatory, with a rated breaking load of 210kN or higher;
750kV and above UHV: GD-type trunnion triangularly distributed frame-type three-hole mounting plates are mandatory, with a rated breaking load of 300kN or higher, and fatigue resistance design is required.
Slight corrosion: Q235B steel + thickened hot-dip galvanized + flat/frame type;
Moderate corrosion: Q345B steel + zinc-aluminum alloy hot-dip galvanized + frame type;
Severe corrosion: Q345B steel + Dacromet treatment + frame type/GD-type trunnion;
Extreme corrosion: 316 stainless steel + frame type/GD-type trunnion, no surface treatment.
If you have special requirements for hole distribution, hole spacing, plate thickness, structural shape, etc., you can communicate with the manufacturer and confirm them through drawings and samples to avoid customized products not meeting your requirements.
