| Brand | ROCKWILL |
| Model NO. | Gas Insulated Switchgear HV (GIS) for power transmission systems-550kV |
| Rated voltage | 550kV |
| Rated normal current | 4000A |
| Series | RHG |
The RHG-550 GIS is a high-voltage SF6 gas-insulated switchgear designed for 550kV power transmission systems. Composed of standard modular components with flanged joints, it enables flexible substation optimization through modular combinations.
The circuit breaker employs a dual-break interrupting chamber with shunt capacitors to balance the voltage across open contacts, achieving a rated short-circuit breaking current of 63kA. The breaker meets E2-M2-C2 class. The spring operating mechanism is compact, maintenance-free, and conforms to oil-free and gas-free requirements.
Insulation performance is verified by low partial discharge testing: under 80% of rated power-frequency withstand voltage, interval PD ≤5pC and insulator PD ≤3pC — exceeding typical IEC requirements. Basin-type insulators are manufactured using advanced vacuum epoxy casting with aluminum flanges and double sealing structures.
| NO. | Items | Units | Parameter Value | |
|---|---|---|---|---|
| 1 | Rated Voltage | kV | 550 | |
| 2 | Rated Current | A | 4000/5000/6300 | |
| 3 | Rated 1 min Power Frequency Withstand Voltage (1min RMS) | Phase-to-Phase & Phase-to-Ground | kV | 740 |
| Across Isolating Fracture | kV | 905 | ||
| 4 | Rated Lightning Impulse Withstand Voltage (Peak Value) | Phase-to-Phase & Phase-to-Ground | kV | 1675 |
| Across Isolating Fracture | kV | 1300 | ||
| 5 | Rated Short-circuit Breaking Current | kA | 1500 | |
| 6 | Rated Short-time Withstand Current / Rated Duration of Short-circuit Withstand | kA/s | 63/3 | |
| 7 | Rated Peak Withstand Current | kA | 170 | |
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.
The insulating property of SF₆ gas relies on its stable molecular structure, which makes electron escape and collision ionization difficult under normal operating voltages, ensuring high insulation resistance. In GIS, insulation is precisely maintained by controlling gas pressure, purity, and electric field distribution to guarantee a uniform and stable electric field between high-voltage conductors and the grounded enclosure.
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.
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