| Brand | ROCKWILL |
| Model NO. | 550kV Gas Insulated Switchgear HV (GIS) |
| Rated voltage | 550kV |
| Rated normal current | 4000A |
| Series | ZF28 |
Product Overview:
ZH28-550 type HGIS 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:
Fully spring mechanism, high reliability.
Excellent breaking ability.
The arc extinguish of CB adopts dual break structure, and shunt capacitor to balance the voltage between open contacts, which improves the breaking ability of short-line fault and the breaking current of short circuit is 63kA.
E2-M2-C2 circuit breaker; E2 electrical endurance; M2 mechanical endurance.
Strong rated current flow capacity.
Excellent insulation level, low partial discharge.
Excellent corrosion resistance.
Advanced Designing tool.
Basin-type insolator with aluminium flange; double sealing structure.
Strict assembly technology.
The domestic first high power spring operation mechanism of circuit breaker has the small volume and is safe and stable, free of maintenance. high reliable and conform to oil free and gas free requirements for operation mechanism.
Interrupter unit adopts shunt capacitor to balance the voltage between open contacts It improves short line fault breaking capability.
Excellent insulation level and low partial discharge. The only company in the industry that can achieve: under the 80% power-frequency withstand voltage (80%×740kV = 592kV), the partial discharge of intervals is lower than 5pC, the partial discharge of the insulator is lower than 3pC. It’s better than the IEC standard that the partial discharge should be lower than 5pC under 1.2 times phase voltage (1.2×550/√3 = 381kV).
The insulator quality is stable and reliable. The basin-type insulator pouring process reaches the international advanced level.
Technical Parameters:
The modular design of HGIS is mainly reflected in integrating the primary switching functions (such as on/off control and isolation) of the switchgear into prefabricated gas-insulated modules. Each module can realize specific functions and is pre-assembled. The advantages are: ① Compact structure, reducing floor space; ② Strong independence between modules, facilitating transportation, installation, and local maintenance in the later stage; ③ Flexible combination of different modules according to actual needs, adapting to diversified bay layout schemes.
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.
