
Unwavering in our dedication to customers and delivering cutting-edge innovations,Bepto stands as your steadfast ally on the journey ahead.
NAL FN18-12 Load Break Switch: 12kV 630A medium voltage LBS for RMU, ABB-compatible modular design, 67kA breaking, puffer-type arc extinguishing, snap-action/spring mechanism, compact proven performance.
Advanced NAL FN18-12 Load Break Switch: Premium NAL/NALF series featuring ABB-compatible modular principle design for 12kV 630A three-pole metal-enclosed and pad-mounted switchgear applications (12-40.5kV ratings available), delivering exceptional 67kA short-circuit closing capacity with 31.5kA/1s rated short-time withstand current (25kA/2s, 20kA/3s), utilizing unique puffer-type arc extinguishing system with heavy-duty steel frame and stand-off insulators, featuring snap-action mechanism type K or stored spring energy mechanism type A options, designed with blade-type interrupters with cast hinges and jaw connectors, offering 85kV lightning impulse withstand across isolating distance and 48kV power frequency withstand.
Modular RMU Building Block Ready: NAL FN18-12 incorporates flexible modular configuration with optional fuse bases type F (max 1600A breaking capacity with 200A fuse), earthing switch type E/EB, motor operator, auxiliary switches, shunt trip, mechanical interlocking, providing proven dependable compact solution for ring main units, metal-enclosed switchgear, pad-mounted switchgear, substations requiring advanced interrupting technology with ABB-similar performance and easy assembly.

| Type | A | A1 | A2 | A3 | B | H | H1 | H2 | K | K1 | M | N | N1 | P | R | S | U | V |
| NAL 12-A/K P=150 | 166 | 320 | 362 | 394 | 90 | 422 | 428 | 510 | 310 | 63 | 412 | 122 | 164 | 150 | 375 | 350 | 75 | 33 |
| NAL 12-A/K P=170 | 166 | 320 | 362 | 394 | 90 | 422 | 428 | 510 | 310 | 63 | 452 | 122 | 164 | 170 | 375 | 390 | 75 | 33 |
| NAL 12-A/K P=210 | 166 | 320 | 362 | 394 | 90 | 422 | 428 | 510 | 310 | 63 | 532 | 122 | 164 | 210 | 375 | 470 | 75 | 33 |
| NAL 17.5-A/K P=170 | 225 | 375 | 418 | 511 | 98 | 534 | 577 | 600 | 441 | 87 | 452 | 122 | 164 | 170 | 500 | 395 | 90 | 18 |
| NAL 17.5-A/K P=210 | 225 | 375 | 418 | 511 | 98 | 534 | 577 | 600 | 441 | 87 | 532 | 122 | 164 | 210 | 500 | 475 | 90 | 18 |
| NAL 24-A/K P=235 | 225 | 375 | 418 | 511 | 98 | 534 | 577 | 600 | 441 | 87 | 582 | 186 | 202 | 235 | 500 | 525 | 90 | 18 |
| NAL 24-A/K P=275 | 225 | 375 | 418 | 511 | 98 | 534 | 577 | 600 | 441 | 87 | 662 | 186 | 202 | 275 | 500 | 605 | 90 | 18 |
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*1250 A: dimension A +2 mm |
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| NAL FN18-12 Load Break Switch Specifications | Technical Parameters | Unit |
|---|---|---|
| Model Number | NAL/NALF FN18-12 (FN18-24 available) | – |
| Brand | Bepto Insulation Systems | – |
| Product Type | Medium Voltage Load Break Switch for RMU (ABB-Compatible) | – |
| Design Principle | Modular Principle (Similar to ABB NAL/NALF) | – |
| Rated Voltage | 12 (24/40.5 available) | kV |
| Rated Current | 630 (up to 1250 available) | A |
| Rated Frequency | 50 / 60 | Hz |
| Number of Poles | Three-Pole | – |
| Arc Extinguishing System | Unique Puffer-Type | – |
| Operating Mechanism Options | Snap-Action Type K / Stored Spring Energy Type A | – |
| Frame Type | Heavy-Duty Steel Frame with Stand-Off Insulators | – |
| Interrupter Type | Blade-Type with Cast Hinges and Jaw Connectors | – |
| Rated Short-Circuit Closing Current | 67 (FN18-12) / 50 (FN18-24) | kA |
| Rated Peak Withstand Current (Dynamic Steady Current) | 67 (FN18-12) / 50 (FN18-24) | kA |
| Rated Short-Time Withstand Current (1s) | 31.5 (FN18-12) / 25 (FN18-24) | kA |
| Rated Short-Time Withstand Current (2s) | 25 (FN18-12) / 25 (FN18-24) | kA |
| Rated Short-Time Withstand Current (3s) | 20 (FN18-12) / 16 (FN18-24) | kA |
| Max. Breaking Capacity in Cooperation with Fuse (NALF) | 1600 (FN18-12) / 900 (FN18-24) | A |
| Max. Fuse Current | 200 | A |
| 1 Min Power Frequency Withstand Voltage (to Earth and Between Poles) | 42 (FN18-12) / 65 (FN18-24) | kV |
| 1 Min Power Frequency Withstand Voltage (Across Isolating Distance) | 48 (FN18-12) / 79 (FN18-24) | kV |
| Lightning Impulse Withstand Voltage (to Earth and Between Poles) Peak | 75 (FN18-12) / 125 (FN18-24) | kV |
| Lightning Impulse Withstand Voltage (Across Isolating Distance) Peak | 85 (FN18-12) / 145 (FN18-24) | kV |
| Ambient Temperature Range | -15°C to +40°C (Maximum 24h average +35°C) | – |
| Maximum Altitude | ≤1000 | m |
| Relative Humidity | Daily ≤95%, Average ≤90% | – |
| Optional Accessories | Motor Operator, Auxiliary Switches, Shunt Trip, Fuse Bases Type F, Earthing Switch Type E/EB, Mechanical Interlocking | – |
| Application | RMU, Metal-Enclosed Switchgear, Pad-Mounted Switchgear, Substations | – |
Bepto is a leading Chinese company in electrical insulation, focused on developing advanced solutions for future power systems. We support transmission and distribution safety and growth, with long-term partners including State Grid, ABB, Schneider, Siemens, and GE. Our services reach clients in over 22 countries.

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Bepto focuses on the global market and provides our clients with products suitable for the local market:
Unwavering in our dedication to customers and delivering cutting-edge innovations,Bepto stands as your steadfast ally on the journey ahead.