| Brand | ROCKWILL |
| Model NO. | High Reliability Dead tank SF6 circuit breaker-550kV |
| Rated voltage | 550kV |
| Rated normal current | 6300A |
| Rated frequency | 50/60Hz |
| Series | RHD |
550kV dead tank SF6 circuit breaker products are composed of inlet and outlet line bushings, current transformers, arc extinguishers, frames, operating mechanisms and other components, the products can be used to cut off rated current, fault current or conversion lines, to achieve the control and protection of the power system, widely used in domestic and overseas electric power, metallurgy, Mining, transportation, and utilities industries.
| Item | Unit | Parameter (1-break) | Parameter (2-break) | |
|---|---|---|---|---|
| Rated voltage | kV | 550 | 550 | |
| Rated current | A | 4000, 5000, 6300 | 4000, 5000, 6300 | |
| Rated frequency | Hz | 50, 60 | 50, 60 | |
| Rated short-circuit breaking current | kA | 63 | 63 | |
| Rated short-time withstand current and duration | kA/s | 63/3 | 63/3 | |
| Rated peak withstand current | kA | 171 | 171 | |
| Rated short-circuit making current | kA | 171 | 171 | |
| Number of breaks | 1 | 2 | ||
| Rated lightning impulse withstand voltage (peak value) | To ground | kV | 1675 | 1675 |
| Break | 2125 | 2125 | ||
| Rated short-time power-frequency withstand voltage (effective value) | To ground | kV | 740 | 740/790 |
|
Break
|
1058 | 1058 | ||
| Rated switching impulse withstand voltage (peak value) | To ground | kV | 1300 | 1300 |
| Break | 1625 | 1625 | ||
The core difference is the arc-extinguishing medium. A VCB uses a high vacuum inside a sealed ceramic or glass envelope — the vacuum rapidly diffuses ions and metal vapor after current zero, achieving arc extinction in <10 ms. An SF₆ CB uses sulfur hexafluoride gas, which has strong electron affinity — it captures free electrons to form heavy negative ions, quickly depleting the arc channel's conductivity.
During the normal operation and interruption processes of a circuit breaker, SF₆ gas can decompose, producing various decomposition products such as SF₄, S₂F₂, SOF₂, HF, and SO₂. These decomposition products are often corrosive, toxic, or irritating, and therefore require monitoring.If the concentration of these decomposition products exceeds certain limits, it may indicate abnormal discharges or other faults within the arc quenching chamber. Timely maintenance and handling are necessary to prevent further damage to the equipment and to safeguard personnel health.
The leakage rate of SF₆ gas must be controlled at an extremely low level, typically not exceeding 1% per year. SF₆ gas is a potent greenhouse gas, with a greenhouse effect 23,900 times that of carbon dioxide. If a leak occurs, it can not only cause environmental pollution but also lead to a decrease in the gas pressure within the arc quenching chamber, affecting the performance and reliability of the circuit breaker.
To monitor the leakage of SF₆ gas, gas leakage detection devices are typically installed on tank-type circuit breakers. These devices help to promptly identify any leaks so that appropriate measures can be taken to address the issue.