Product Overview
The FN5-12 series is an indoor AC high-voltage load switch and load switch-fuse combination unit for three-phase 50 Hz systems rated 12 kV. Fully type-tested and proven in long-term service, it meets IEC 420 and GB 3804 and provides the three operating positions of switching, isolation and earthing in one compact, light frame for 10 kV power distribution. It may be used on its own as a load switch or combined with current-limiting fuses to protect distribution transformers, and its design effectively prevents open-phase operation of the equipment. Rated at 400 A or 630 A with 12.5 / 20 kA short-time withstand current, it is widely applied in ring-main units and box-type substations.
Product Display
Model Designation
Model format: FN5-12 R D (L) / rated current
- FN: indoor load switch; 5: design sequence number; 12: rated voltage, kV
- R: with fuse
- D: with earthing switch
- (L): with trip device (striker)
- Final figure: rated current, A
Service Conditions
- Ambient temperature: -25 °C to +40 °C
- Altitude: 1000 m or less
- Air relative humidity: daily average 95% or less, monthly average 90% or less
- Surrounding air free from corrosive or flammable gas and obvious water-vapour contamination
- No frequent or severe vibration
Construction
The FN5-12 is built on a steel base frame carrying support insulators, the moving and fixed contacts, arc-quenching (fuse) tubes and guide plates. The open/close mechanism drives the three-position switching, while a built-in interlock ties the load switch, earthing switch and fuse assembly together to prevent maloperation, and a trip (striker) device lets the fuses open the switch on fault.
The unit can be operated with a CS6-1 type operating mechanism linked through a bent connector and welded steel pipes supplied by the user. Its compact, lightweight structure and clear on-off-earth indication make it suitable for metal-enclosed ring-main and box substation panels.
Technical Data
| Item | Unit | 400 A frame / 630 A frame |
|---|---|---|
| Rated voltage | kV | 12 / 12 |
| 1-minute power-frequency withstand voltage | kV | 42 / 48 |
| Rated current | A | 400 / 630 |
| 4 s short-time (thermal) withstand current | kA | 12.5 / 20 |
| Peak withstand (dynamic) current | kA | 31.5 / 50 |
| Rated breaking (load) current | A | 400 / 630 |
| Short-circuit making current (peak) | kA | 31.5 / 50 |
| Fuse SDLA*J, rated 50 A | — | fuse-links 6.3, 10, 16, 20, 25, 31.5, 40 A |
| Fuse SFLA*J, rated 100 A | — | fuse-links 50, 63, 71, 80, 100 A |
| Fuse SKLA*J, rated 125 A | — | fuse-link 125 A |
Standards
The FN5-12 series is type-tested to IEC 420 for AC high-voltage switch-fuse combinations and GB 3804 for 3-63 kV AC high-voltage load switches.
Installation & Dimensions
Installation Diagram
The FN5-12 is an indoor panel-mounted unit supplied in two frames, the bare load switch and the version with the CS6-1 operating mechanism linkage. Mount it vertically on a flat panel, verify the fixing-hole pattern and phase clearances against the outline drawing, and provide adequate operating clearance for the mechanism and the bent connector or welded steel pipes. All primary and secondary connections must comply with local utility standards.
| Item | Value (mm) |
|---|---|
| Overall width (front view) | 840 |
| Base / panel mounting width | 560 |
| Phase (pole) spacing | 200 |
| Side-view depth | 550 |
| Side-view inner section | 330 |
| Upper frame height | 280 |
| Lower frame height | 440 |
| Terminal / insulator clearance | 240 or more |
| CS6-1 operating handle height | 1200 |