Porcelain crossarm is a conical or cylindrical porcelain insulators for overhead power lines, also known as the porcelain insulator crossarm. In addition to the same fixed wire and the function of the ground insulation which is the same as the common line insulator, the whole or part of the iron or wooden cross arm can be replaced.
Porcelain cross arm with metal accessories and without metal accessories two. Porcelain cross arm with more than medium voltage and above voltage level is provided with metal accessories. Accessories have two holes, a hole for installing and fixing bolt, another close to the root of the hole is when the porcelain crossarm bear unbalanced tension and the hole of bolt stress is shear can make porcelain cross arm along the fixed rotating bolt, to ease on both sides of the unbalanced tension. The porcelain cross arm, fixed and lashing wires also have two, a is directly binding, another is in porcelain head with connecting fittings, to the suspension line clamp.
China has produced forming products of porcelain cross arm electrical, mechanical properties and the same voltage level ordinary transmission line insulator is compared, its characteristics is: 1 porcelain crossarm insulation distance and the creepage distance is relatively large, 50% of the full wave impulse flashover voltage and dry, wet flashover voltage is higher; 2 porcelain cross arm of the magnet is relatively long, low mechanical bending strength, after considering the factor of safety, allowing maximum load than the same voltage grade ordinary line insulator small. Therefore, porcelain cross arm is not suitable for the wire cross section and the span of the larger circuit. Commonly used porcelain cross arm has 35KV porcelain cross arm, 10KV porcelain cross arm and 10KV porcelain pull rod three.