Electric angle steel cross arm

Electric angle steel cross arm

Electric angle steel cross arm is an important supporting component in power lines, mainly used to fix insulators, wires, lightning arresters and other equipment in overhead lines, playing a supporting and fixing role, and protecting the stability and safety of the line. Here is a detailed introduction:

1、 Function

support equipment

Fixed insulators (such as porcelain insulators, composite insulators) are used to maintain insulation distance between the conductor and the pole (or tower).

Supporting conductors, lightning conductors (overhead ground wires), bearing vertical loads (such as conductor weight) and horizontal loads (such as wind and tension) of the line.

Protect the safety of the line

Confirm the electrical distance between wires and between wires and poles to avoid short circuits or leakage.

In the event of a power outage or extreme weather conditions such as strong winds or icing, limit the displacement of the line through its own strength to reduce the risk of faults.

Easy to construct and maintain

Provide standardized installation structures, simplify the process of line installation, and facilitate later maintenance and equipment replacement.

2、 Material and specifications

material

Hot dip galvanized angle steel: The commonly used material is Q235B steel, which has undergone hot-dip galvanizing treatment on the surface (zinc layer thickness ≥ 65 μ m). It has good corrosion resistance (based on actual reports) and is suitable for most outdoor environments.

Stainless steel angle steel: In special scenarios such as coastal areas, high humidity, and highly corrosive areas, stainless steel material can be used, which has high cost but stable and strong performance.

specifications

Expressed as * * edge length * edge length * thickness (mm) * * of angle steel, common specifications include:

50 × 50 × 5 (applicable to low-voltage lines or light load scenarios)

63 × 63 × 6, 75 × 75 × 8 (applicable to high voltage lines of 10kV and below)

90 × 90 × 10, 100 × 100 × 10 (applicable to 35kV and above high-voltage lines or large-span towers)

The length is customized according to the pole model and line requirements, commonly ranging from 1.0 to 3.0 meters.

3、 Classification and Application Scenarios

Classified by voltage level

Low voltage crossbar: used for 0.4kV low-voltage distribution lines, with smaller specifications (such as 50 × 50 × 5), usually installed in a single piece.

High voltage cross arm: used for 10kV and above high voltage lines, with larger specifications (such as 75 × 75 × 8), and may require multiple combinations (such as double cross arms to enhance stability).

Classified by installation method

Straight cross arm: Installed on a straight pole (middle pole), it only bears vertical loads and small horizontal wind forces, usually a single cross arm.

Tension resistant cross arm: installed on tension resistant poles (corner poles, terminal poles), it needs to withstand wire tension, and often uses double cross arms or reinforced structures.

Corner cross arm: used at the corner of the line, adjust the length of the cross arm according to the corner angle (such as 30 °, 60 °, 90 °) or adopt special design.

Classified by structural form

Single cross arm: a single angle steel installed independently, suitable for straight bars with small loads.

Double cross arm: Two angle steels are installed parallel (with a spacing of about 10-15 cm) and connected by bolts, used for towers with large loads or important poles (such as tension rods and terminal poles).

4、 Installation points

Preparation before installation

Check whether the specifications and length of the cross arm meet the design requirements, and inspect whether the hot-dip galvanized layer is complete (without rust or missing plating).

Preparation tools: wrench, level ruler, safety belt, bolt (such as M16 hot-dip galvanized bolt), gasket, etc.

Installation steps

Positioning: According to the design requirements, mark the installation height of the cross arm on the pole (for example, the distance between the low-voltage line cross arm and the pole top is about 50cm, and the distance between the high-voltage line cross arm and the pole top is about 80cm).

Fixed:

Fix the cross arm onto the pole with a U-shaped clamp or M-shaped iron, and confirm that the cross arm is perpendicular to the pole (calibrated with a level ruler).

The bolt needs to be threaded out from the inside of the pole, the nut should be tightened on the outside, and washers should be added to both ends of the bolt to confirm a secure connection.

Insulator installation: Drill holes on the cross arm and fix the insulators with bolts (such as needle insulators and butterfly insulators). The hole spacing should meet the requirements of wire spacing (such as wire spacing for low-voltage lines ≥ 0.6 meters, and wire spacing for high-voltage lines ≥ 1.5 meters).

precautions

The installation of the cross arm should be flat and firm, with a deviation of ≤ 20mm in the up and down or left and right torsion.

The cross arm of the corner pole and terminal pole should be pre biased towards the stressed side (generally inclined by 10-20mm) to balance the tension of the wire.

When installing multiple lines on the same pole, the spacing between the cross arm layers must meet the specifications (such as a spacing of ≥ 1.2 meters between 10kV and 0.4kV lines).

5、 Maintenance and repair

regular inspection

At least once a year, conduct inspections to check whether the cross arm has rust, deformation, loose bolts, and other issues.

It is important to inspect the cross arms of tension bars and corner bars, as they are prone to fatigue damage due to high stress.

Anti corrosion treatment (based on actual reports)

When the galvanized layer is found to be damaged or partially corroded, the rust should be removed and anti rust paint+silver powder paint (or hot-dip galvanizing repair agent) should be applied.

Cross arms that are severely corroded (such as wall thickness reduction ≥ 10%) or deformed should be replaced in a timely manner.

Dealing with extreme weather conditions

After typhoon, rainstorm, icing and other disasters, it is necessary to check whether the cross arm is displaced, whether the bolts are loose, and timely and carefully service and reinforce.