400kV 210kN Long Rod Silicone Rubber Insulator

What is a 400kV transmission line?

Complete Description of 400kV Transmission Lines

I. Classification

400kV belongs to ultra-high voltage (EHV) AC transmission lines, the mainstream voltage for overseas main power grids (widely used in Europe, Africa, Southeast Asia, and India); domestically, the mainstream is 330kV/500kV, and 400kV is mostly used for overseas projects, cross-border power grid interconnection, and ±400kV DC projects.

Core Applications
Long-distance transmission from large-scale thermal power, hydropower, and wind power bases; Interconnection of large regional power grids, improving grid reserve and stability; Large-capacity industrial loads and cross-border power transmission; Convergence and transmission lines for new energy bases.

Transmission Capacity
Single circuit: 200～450MW
Double circuit: 600～2000MW
Economic transmission distance: 200～600km

Impluse Testing

Frequency Testing

our accessories

The Corona Ring

1) Corona Discharge: Air ionization produces blue light and a hissing sound. Long-term corona discharge will:

Corrode the silicone rubber surface, accelerating aging, pulverization, and cracking;

Produce ozone and nitrogen oxides, corroding the core rod and fitting interface, causing interface water seepage and core rod brittle fracture.

2) Local Arcing, Dry Area Arcing: In rainy or foggy weather, a water film forms on the insulator surface. Areas with concentrated voltage are prone to dry area arcing, repeatedly burning the silicone rubber, causing ablation holes, directly reducing insulation strength, and even flashover tripping.

Function of Corona Rings
Metal ring conductor sleeves are installed at the high-voltage end (both ends are installed in some heavily polluted areas):
They uniformly distribute the concentrated electric field on the conductor side, smoothing the potential gradient;
They significantly reduce the surface electric field strength of the first shed, suppressing corona and arcing;

400kV standard requirement: The maximum electric field strength at the end must be controlled within 22kV/cm. Without an equalizing ring, it will exceed the standard by 3 to 5 times.

Bird Protection Ring

Bird-proof Ring Structure and Principle
Generally installed at the grounding end of the insulator (tower side), a metal disc/ring baffle:
Blocks droppings: When a bird lands on the crossarm, its droppings fall vertically and are blocked by the metal ring, preventing them from flowing along the insulator skirt and cutting off the conductive contaminant path;
Prevents perching:The annular raised disc's concave/outward-facing design prevents birds from firmly standing on the hardware above the insulator, reducing the time spent pausing to defecate;
Increases air gap:The disc extends outward, increasing the effective insulation distance between the bird's body and the high-voltage conductor, preventing short-circuit discharge when wings are spread.