SFX-12 series solid insulated standardized ring main unit, circuit breaker cabinet, is developed according to “The standardized Design and Customization Scheme of 12kV Ring Main Unit”, adopts the top expansion busbar form, the interface type of the primary and secondary equipment conforms to the state grid standardization requirements, with strong general interchangeability. SFX-12 series ring main unit does not need SF6 gas, reduces the damage to the atmosphere, with significant ecological benefit, it is the future direction of environmentally-friendly electrical equipment. SFX series solid insulated medium is less affected by altitude and humidity, ring main unit in high altitude, condensation prone areas show its superior electrical performance. EFX series standardized ring main unit is mainly used in the housing and distribution projects of the State grid, and is also suitable for the transformation of power system urban network, power distribution station and load center power station, petrochemical industry, steel and mining industry, general enterprises and institutions, high-rise buildings, etc.
| Project | Unit | Circuit breaker cabinet | |
| Rated voltage | kV | 12 | |
| Power frequency withstand voltage（1min） | Phase to phase and phase to ground | kV | 42 |
| Between open contacts | kV | 48 | |
| Lightning impulse withstand voltage | Phase to phase and phase to ground | kV | 75 |
| Between open contacts | kV | 85 | |
| Rated frequency | Hz | 50 | |
| Rated current | A | 630 | |
| Rated short-circuit breaking current | kA | 20 | |
| Rated short-time withstand current | kA/s | 20/4 | |
| Rated peak withstand current | kA | 50 | |
| Annual leakage rate | ≤0.1% | ||
| Arcing test | 20kA 1s | ||
| Protection grade | Air box | IP 67 | |
| Ring main unit | IP 4X | ||
extension-method | Top expansion | ||
