| Brand | ROCKWILL |
| Model NO. | EHV Gas Insulated Switchgear (GIS) Original Manufacturer-550kV |
| Rated voltage | 550kV |
| Rated normal current | 6300A |
| Series | RHG |
The RHG Series GIS is a 550kV-class SF6 gas-insulated switchgear for EHV transmission systems, also applicable at 330kV, 345kV, and 400kV levels. It integrates circuit breaker, disconnector, earthing switch, current transformer, busbar, and bushing in a compact earthed enclosure with SF6 insulation. The single-break arcing chamber and hydraulic operating mechanism deliver reliable interruption with minimal external piping and automatic pressure regulation.
| No. | Item | Unit | Value |
|---|---|---|---|
| 1 | Rated voltage (Ur) | kV | 550 |
| 2 | Rated frequency (fr) | Hz | 50/60 |
| 3 | Rated normal current (Ir) | A | 6300 |
| 4 | Rated short-circuit breaking current (Isc) | kA | 63 |
| 5 | Power-frequency withstand voltage (Ud, 1min) — To earth | kV | 740 |
| 6 | Power-frequency withstand voltage (Ud, 1min) — Across isolating distance | kV | 840 |
| 7 | Lightning impulse withstand voltage (Up) — To earth | kV | 1675 |
| 8 | Lightning impulse withstand voltage (Up) — Across isolating distance | kV | 2125 |
| 9 | Switching impulse withstand voltage (Us) — To earth | kV | 1300 |
| 10 | Rated short-time withstand current (Ik) | kA | 63 |
| 11 | Rated peak withstand current (Ip) | kA | 164 |
| 12 | Rated short-circuit duration (tk) | s | 3 |
| 13 | Mechanical life — Circuit breaker / Disconnector | operations | 5000 |
| 14 | SF₆ annual leakage rate | %/year | ≤0.1 |
| 15 | Circuit breaker operating mechanism | — | Hydraulic |
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.
Equipped with current transformers and various sensors, this GIS integrates overcurrent, short-circuit, ground fault and overvoltage protection functions; it monitors real-time electrical parameters, automatically trips the circuit breaker and triggers protection actions once current or voltage abnormalities are detected to isolate faulty circuits and guarantee safe operation of the power system and equipment.
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