Power Fittings Manufacturers Introduce The Types, Functions And Selection Of Crossarms

1. The role of Dead End Clamp.

The cross arm is an important part of the tower. Its function is to install insulators and hardware to support the conductors and lightning conductors, and keep them at a certain safe distance as required.

Commonly used cross arms are angle iron cross arms and wooden cross arms. Low-voltage porcelain cross arms are used in some areas.

2. Classification of cross arms.

According to the purpose, it can be divided into: straight cross arms, corner cross arms, tension cross arms;

According to the material, it can be divided into: iron cross arms, porcelain cross arms, synthetic insulation cross arms;

According to the voltage level: high voltage cross arms, low voltage cross arms;

According to the structure: T-shaped cross arms, seven-shaped cross arms, door-shaped cross arms, triangle cross arms, one-shaped cross arms, etc.

3. Selection of cross arms.

The cross sections of angle iron cross arms and wooden cross arms should be selected according to the cross sections and number of conductors, but not less than the values ​​in the following table.

The length of angle iron crossarms and wooden crossarms is determined by the number of conductors, the span between adjacent poles and the distance between lines.

Crossarm name Crossarm length/mm Crossarm section/mm
Four-wire angle iron crossarm 1480 50×50×5
Four-wire square wood crossarm 1600 70×90 or 80×80
Two-wire angle iron crossarm 750 50×50×5
Two-wire square wood crossarm 800 70×90 or 80×80
Table 1 Introduction to several commonly used crossarm lengths and cross-sections

Span/m 40 and below 50 60 70
Distance between lines/m 0.3 0.4 0.45 0.5
Table 2 Minimum distance between lines at different spans of low-voltage lines

Low-voltage porcelain crossarms are finished products produced in factories and are fixed to the poles with iron brackets during installation. Low-voltage porcelain crossarms are suitable for straight poles and angle poles within 15°.

Angle iron crossarms should be prevented from rusting, such as galvanizing or painting;

Wooden crossarms should be treated with anti-corrosion;

The widely used porcelain crossarm voltage is 10KV and 35KV new insulators, with good electrical performance, reliable operation, simple structure, easy installation and maintenance, and can save steel and reduce line costs. Its disadvantage is low mechanical strength, which limits the length of the entire porcelain crossarm, thus affecting its scope of application.