| Brand | ROCKWILL |
| Model NO. | 420kV HV Gas Insualted Switchgear(GIS) |
| Rated voltage | 420kV |
| Rated normal current | 4000A |
| Series | ZF28 |
Product overview：
ZF28-420 type GIS is composed of standard modules through flanged joint, which can meet the demand for substation optimization design through the flexible combination between modules. It saves space and conforms to technical requests.
This product can be applied to power system, power generation, rail transportation, petrochemical, metallurgy, mining, building materials and other large industrial consumer.
Features and advantages of the product：
Horizontal circuit breaker structure, integrated transportation, high space utilization.
Fusion of high parameters and high reliabilityCircuit breaker, disconnector and grounding switch have a mechanical life of 10,000 times.
Advanced circuit breaker, excellent breaking capacity.
Mature pure spring operating mechanism application.
Basin insulator with aluminum flange with double seal structure.
Import of key components, accessories and major production equipment.
The GIS phase spacing is 670mm and the standard spacing width is 2050mm (see layout). The whole interval of three-phase integrated transportation, its technological innovation level is domestic leading, international advanced level.
Arrangement of circuit breaker is horizontal, it’s convenient for overhauling and emergency maintenance; it also will make lighter impact to the ground.
Excellent insulation level and low partial discharge. The only company in the industry that can achieve: under 1.2 times phase voltage (1.2×420/√3 = 291kV), the partial discharge of intervals is lower than 5pC, the partial discharge of the insulator is lower than 3pC.
Technical Parameters：
Insulation Principle:
In an electric field, the electrons in SF₆ gas molecules are slightly displaced from the nuclei. However, due to the stability of the SF₆ molecular structure, it is difficult for electrons to escape and form free electrons, resulting in high insulation resistance. In GIS (Gas-Insulated Switchgear) equipment, the insulation is achieved by precisely controlling the pressure, purity, and electric field distribution of the SF₆ gas. This ensures a uniform and stable insulating electric field between the high-voltage conductive parts and the grounded enclosure, as well as between different phase conductors.
Under normal operating voltage, the few free electrons in the gas gain energy from the electric field, but this energy is not sufficient to cause collision ionization of the gas molecules. This ensures the maintenance of the insulating properties.
Due to the excellent insulation performance, arc extinguishing performance and stability performance of SF6 gas, GIS equipment has the advantages of small footprint, strong arc extinguishing ability and high reliability, but the insulation ability of SF6 gas is greatly affected by the uniformity of the electric field, and it is easy to have insulation abnormalities when there are tips or foreign objects inside the GIS.
GIS equipment adopts a fully enclosed structure, which brings the advantages of internal components without environmental interference, long maintenance cycle, low maintenance workload, low electromagnetic interference, etc., while also having problems such as complex single overhaul work and relatively poor detection methods, and when the closed structure is eroded and damaged by the external environment, it will further bring a series of problems such as water ingress and air leakage.
