| Brand | ROCKWILL |
| Model NO. | Low maintenance HV Gas Insulated Switchgear (GIS) for Substations-72.5kV to 145kV |
| Rated voltage | 145kV |
| Rated normal current | 2000A |
| Series | ZF12 |
Gas Insulated Switchgear (GIS) is a 3-phase AC high-voltage solution engineered for precise control, measurement, protection, and switching of transmission lines up to 145kV.
The ZF12-72.5/126/145 GIS integrates essential substation components including circuit breakers, disconnectors, earthing switches, voltage transformers, current transformers, and surge arresters within a three-phase common enclosure. Its innovative three-position disconnector-earthing switch (D/E) combination optimizes the internal layout, delivering a compact and space-efficient solution with mechanical interlocks for safe operation.
| Specifications | Unit | 72.5 | 126 | 145 |
|---|---|---|---|---|
| Rated Voltage | kV | 72.5 | 126 | 145 |
| Rated Current | A | 2000 | 3150 | 3150 |
| Rated Frequency | Hz | 50/60 | 50/60 | 50/60 |
| Rated Short-time Withstand Current (3s) | kA | 31.5 | 40 | 40 |
| Rated Peak Withstand Current | kA | 80 | 100 | 100 |
| 1min Power-frequency Withstand Voltage (r.m.s) | ||||
| — To earth & between poles | kV | 140 | 230 | 275 |
| — Across isolating distance | kV | 160 | 265 | 315 |
| Lightning Impulse Withstand Voltage (peak) | ||||
| — To earth & between poles | kV | 325 | 550 | 650 |
| — Across isolating distance | kV | 375 | 630 | 750 |
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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