Overview
The FN3-12 and FN3-12R/S series are indoor high-voltage load break switches designed for 50Hz AC systems operating at 6kV or 12kV. They provide reliable switching of load currents and support protection applications when used with compatible high-voltage fuses.
Engineered for frequent operation with minimal maintenance, these switches integrate seamlessly into medium-voltage indoor switchgear panels and can be equipped with CS2 or CS3 manual operating mechanisms for enhanced safety and control.
Key Ratings Snapshot
| Parameter | Value |
|---|---|
| System Frequency | 50 Hz |
| Rated Voltage | 6 kV / 12 kV |
| Rated Current | 200 A / 400 A / 630 A |
| Short-Time Withstand (3s) | 20 kA |
| Peak Withstand Current | 50 kA |
| Mechanical Life | >=2,000 operations |
| Arc-Extinguishing Medium | Vacuum (RN3-type) |
| Operating Mechanism | CS2 or CS3 manual |
Model Designation
- F: Load Break Switch
- N: Indoor Application
- 3: Design Sequence Number
- 12: Rated Voltage (kV)
- R: With Load Breaking Capability
- S: With Integrated Earth (Grounding) Switch
Construction
The switch incorporates an RN3-type arc-extinguishing vacuum interrupter for reliable load current interruption. Terminal markings include P1/P2 for power input/output and S1/S2 for fuse connections where applicable. Always ensure the circuit is de-energized before installation or maintenance.
Do not operate under load without verifying compatibility with the connected fuse’s interrupting rating. Use only manufacturer-specified replacement parts to maintain safety and compliance with applicable standards.
Technical Parameters
Service Conditions
- Ambient Temperature: Standard service conditions apply
- Altitude: <=1,000 m (standard); consult technical team for higher altitudes
- Humidity: Non-condensing, per IEC 62271
- Special Requirements: Custom configurations available upon request
Technical Data
| Parameter Symbol |
Value |
|---|---|
| System Frequency f |
50 Hz |
| Rated Voltage Ue |
6 kV / 12 kV |
| Rated Current In |
200 A / 400 A / 630 A |
| Rated Short-Time Withstand Current (3s) Isc |
20 kA |
| Rated Peak Withstand Current Ipk |
50 kA |
| Mechanical Life N |
>=2,000 operations |
| Arc-Extinguishing Medium | Vacuum (RN3-type interrupter) |
| Operating Mechanism | CS2 or CS3 manual mechanism |
Installation & Wiring
Installation Diagram
The FN3-12 series is designed for compact indoor mounting with standardized interface dimensions for ease of integration into switchgear panels.
Outline Dimensions
| Dimension | Value (mm) |
|---|---|
| Overall Height | 480 |
| Overall Width | 260 |
| Overall Depth | 190 |
| Mounting Hole Spacing (Vertical) | 320 |
| Mounting Hole Spacing (Horizontal) | 200 |
| Phase Spacing | 150 |
Selection & FAQs
Selection Guide
- Select the 6kV or 12kV version and 200A, 400A or 630A rated current from maximum load, switching frequency and panel temperature-rise limits.
- Confirm the switch’s rated load-breaking duty separately from its 20kA three-second and 50kA peak withstand ratings; withstand does not equal fault interruption.
- Where short-circuit protection is required, specify the fuse-combination version and coordinate fuse voltage, current, minimum breaking current, striker and time-current curve.
- Select the required R/S configuration, earthing switch and CS2 or CS3 operating mechanism, then verify mechanical interlocks and door-access logic.
- Check the 480×260×190mm reference envelope, 150mm phase spacing, mounting holes, busbar alignment, clearances and grounding against the panel drawing.
Frequently Asked Questions
Q1: Can the FN3-12 load break switch interrupt short-circuit currents alone?
No, the switch cannot interrupt short-circuit currents independently. It must be coordinated with backup fuses for fault protection. Specify fuse requirements during system design.
Q2: Is the FN3-12 suitable for high-altitude installations above 1,000 meters?
Standard models are rated for altitudes up to 1,000 meters. For higher elevations, consult our technical team for derating factors and custom configurations.
Q3: Which operating mechanism is used for the FN3-12 vacuum switch?
It utilizes either the CS2 or CS3 manual operating mechanism. The vacuum RN3-type interrupter ensures a mechanical life of at least 2,000 operations.
Q4: Are custom configurations available for specific project requirements?
Yes, custom configurations are available upon request. Contact our sales team with your specific technical parameters and environmental conditions for technical evaluation.
Q5: What factory tests are performed before shipment?
Routine testing is performed prior to dispatch. For detailed test certificates or specific type test reports, please contact us for details.
Q6: Where is the FN3-12 indoor high voltage switch typically applied?
It is designed for 6 kV and 12 kV indoor high voltage switchgear applications. Rated currents range from 200 A to 630 A at 50 Hz.
Q7: How many rated current options are available for this 12kV switch?
The FN3-12 is available in 200 A, 400 A, and 630 A rated currents. Specify your exact load requirements when requesting a quotation.