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FLN36-24 SF6 Indoor Load Break Switch
Indoor 3-position SF6 load break switch. Manual or motorized. For 24kV ring main distribution. FLN36-24 SF6 indoor load break switch is a three-position switching device rated at 24kV, designed for gas-insulated ring main units in medium voltage distribution networks. Built to relevant IEC standards, this SF6 LBS features a sealed pressure system with three stable positions: Closed, Open, and Earthed. The modular architecture supports configurations from 2-switch to 4-switch assemblies, with optional VCB integration. Rated for 630A, this indoor load break switch serves urban underground cable networks, residential substations, and industrial ring feeders where SF6 insulation ensures reliable operation independent of ambient conditions.
- Overview
- Applications
- Technical Data
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- Quality Control
- Recommended Products
FLN36-24 Indoor SF6 Load Break Switch - 24kV, 630A Three-Position
FLN36-24 is an SF6 gas-insulated load break switch for 24kV distribution, with the switch contacts, arcing chamber and earthing switch sealed inside a gas-filled enclosure. Rated 630A with three stable positions - Closed, Open and Earthed - it is the switching element in 24kV ring main units and compact substations serving 20kV and 22kV networks.
WHY SF6 AT 24kV
The dielectric strength of SF6 is roughly three times that of air at the same pressure. At 12kV that advantage is convenient; at 24kV it becomes structural. Insulating a 24kV switch in air requires clearances that make the assembly physically large, whereas the same duty in sealed SF6 fits into an enclosure not much bigger than a 12kV air-insulated unit. For 20kV and 22kV secondary distribution, where substation space is often the binding constraint, this is usually the deciding factor.
SEALED CONSTRUCTION AND ENVIRONMENTAL IMMUNITY
Because the switching contacts live inside a hermetically sealed chamber, the insulation is unaffected by dust, humidity, salt fog, condensation and insect ingress. There is no internal air gap whose dielectric strength degrades as the environment does its work. That is what makes gas-insulated switches the practical choice for Gulf coastal and desert installations, flood-prone and below-grade chambers, and any site where enclosure integrity cannot be guaranteed over a twenty-year life.
The gas chamber is sealed for life with no refilling required, and a pressure indicator provides local status. Optional density monitoring with remote alarm is recommended for unmanned installations.
THREE-POSITION SWITCHING
A single interlocked mechanism drives the switch between Closed, Open and Earthed. The earthed position provides a positive, mechanically interlocked earth without any separate earthing device, and interlocking prevents earthing a live circuit or opening the cable compartment before the earth is applied.
THE F-GAS CONSIDERATION
Buyers in the EU and Eastern Europe should weigh the space and environmental advantages against F-Gas obligations. SF6 is a fluorinated greenhouse gas subject to reporting, leak-checking and end-of-life recovery requirements. Where those obligations govern the procurement decision, an air-insulated 24kV switch is the appropriate alternative, accepting the larger footprint and greater environmental sensitivity.
MARKET FIT
Serves 22kV networks in the UAE and Qatar, 20kV networks across Eastern Europe and CIS, and 22kV municipal reticulation in Africa. Available at 50Hz and 60Hz, with GOST 15150 climatic versions for CIS supply.
PRIMARY APPLICATIONS
- Ring main unit switching cells in 24kV compact cabinets serving 20kV and 22kV networks.
- Urban cable ring feeder switching points where footprint is constrained.
- Compact and packaged substations on 22kV Gulf networks and 20kV Eastern European networks.
- Coastal and desert installations where air-insulated switchgear degrades - the sealed chamber is immune to salt fog and dust.
- Below-grade, basement and flood-risk substation chambers.
- Renewable energy collection switching at 22kV, where higher collection voltage reduces cable losses across large solar and wind sites.
- Industrial estate and free-zone distribution ring networks.
- Transformer circuit switching, paired with HV fuses where short-circuit protection is required.
- Municipal reticulation on 22kV African networks.
WHEN TO SPECIFY GAS-INSULATED AT 24kV
Choose FLN36-24 where substation space is limited, the environment is harsh - coastal, desert, humid, flood-prone or below grade - or the installation is unmanned with limited maintenance access. Choose an air-insulated 24kV switch where F-Gas compliance burden is the governing concern and the environment is benign, dry and clean.
REGIONAL FIT
- UAE and Qatar: 22kV distribution in coastal and desert conditions, subject to DEWA and KAHRAMAA material approval. The environmental case for sealed construction is strongest here.
- Eastern Europe: 20kV mainstream distribution. Confirm the client position on F-Gas before selecting SF6.
- Russia and CIS: 20kV urban networks, GOST R certified, climatic versions available.
- Africa: 22kV municipal and industrial reticulation, including coastal and flood-prone urban areas.
NOT SUITABLE FOR
Direct short-circuit interruption without fuses or upstream breaker protection. Networks at 10kV and 11kV, where the 12kV class is correct and more economical. 33kV and 35kV systems. Projects where client policy prohibits SF6.
TECHNICAL DATA - FLN36-24 SF6 Load Break Switch
| Parameter | Value |
| Compliance | IEC 62271-103, IEC 62271-102 (earthing switch function), IEC 62271-1 |
| ELECTRICAL RATINGS | |
| Rated voltage | 24 kV |
| Rated frequency | 50 Hz / 60 Hz |
| Rated power-frequency withstand voltage (1 min) | 50 kV to earth / 60 kV across isolating distance |
| Rated lightning impulse withstand voltage (BIL) | 125 kV peak / 145 kV across isolating distance |
| Rated normal current | 630 A |
| Rated load breaking current | 630 A |
| Rated short-circuit making current | 50 kA peak |
| Rated short-time withstand current | 20 kA for 4 s |
| Rated peak withstand current | 50 kA |
| Rated cable-charging breaking current | 16 A |
| Rated transformer no-load breaking current | 6.3 A |
| GAS SYSTEM | |
| Insulation and arc-quenching medium | SF6 |
| Rated filling pressure (gauge) | 0.04 - 0.05 MPa at 20 C |
| Sealed for life | No refilling required over design service life |
| Gas monitoring | Pressure indicator standard; density switch with remote alarm optional |
| Leakage rate | Less than 0.1% per year |
| SWITCH FUNCTION | |
| Positions | Closed / Open / Earthed - single mechanism, three stable positions |
| Earthing switch making capacity | 50 kA peak |
| Interlocking | Mechanical, preventing earthing of a live circuit and compartment access before earthing |
| Operation | Manual lever standard; motorised AC/DC 110 V or 220 V optional |
| Auxiliary switch | 2NO2NC standard, expandable |
| Position indication | Mechanical indicator, direct-driven from the main shaft |
| ENDURANCE | |
| Mechanical life | 2,000 operations minimum (class M1) |
| Load breaking operations at rated current | 100 operations minimum (class E3) |
| Earthing switch making operations | 5 operations at rated making current |
| CONSTRUCTION | |
| Enclosure | Sealed welded steel or stainless steel gas chamber |
| Protection degree | IP65 for the gas-filled compartment |
| Main contact material | Copper alloy, silver plated |
| Bushings | Cycloaliphatic epoxy resin |
| Cable connection | Separable elbow connectors 200 A / 400 A / 630 A, or bolted lug |
| Mounting | Panel-mounted within ring main cabinet |
| Weight | Approximately 80 - 120 kg |
| SERVICE CONDITIONS | |
| Ambient temperature | -25 C to +55 C |
| Altitude | Up to 1000 m standard; up to 2000 m on request |
| Relative humidity | Unrestricted for the sealed chamber |
OPTIONS
Motorised operating mechanism for SCADA | HV fuse combination with striker-pin tripping | SF6 density monitor with remote alarm | additional auxiliary contacts | position indication contacts | low-temperature version for GOST 15150 climatic supply | separable connector interface to customer cable specification
PRE-SALES SELECTION
- Application review against your duty: rated current, breaking capacity, operating sequence, and expected switching frequency.
- Retrofit and replacement sizing. Send us the existing unit's model, pole-centre distance and mounting dimensions and we will confirm interchangeability before you order.
- Grid verification: 12kV class for 10kV (Russia/CIS) and 11kV (Middle East/Africa) networks; 24kV for 20kV and 22kV; 40.5kV for 35kV. Saudi Arabian supply verified at 60Hz.
- Coil, motor and auxiliary-contact configuration specified to your control voltage (AC/DC 110V or 220V) and SCADA interface requirement.
- Low-temperature variants with cold-rated grease and anti-condensation heating for CIS winter service.
MARKET ACCESS AND DOCUMENTATION
- Type-test reports to IEC 62271-100 / IEC 62271-102 / IEC 62271-103 as applicable, issued with the shipment.
- Third-party certification (KEMA, ASTA, CESI, TUV) available where tender documents require witnessed evidence rather than a manufacturer's report.
- Certification support for SASO SABER, SONCAP, KEBS PVoC, ICIGI and GOST R submissions, including HS-code classification (Nigeria has required 10-digit HS codes since March 2025).
TESTING AND DELIVERY
- 100% routine testing before dispatch: power-frequency withstand, contact resistance, mechanical characteristic curve, timing test, and auxiliary circuit verification.
- Individual test report supplied per serial number.
- Export packing with desiccant and moisture barrier; palletised for consolidated shipment.
- Documentation: routine test report, type-test certificate, dimensional drawing, wiring schematic, O&M manual, spare parts list.
AFTER-SALES
- Installation and commissioning guidance, remote support or engineer dispatch.
- Maintenance training covering mechanism inspection, contact wear measurement and vacuum interrupter integrity testing.
- Wear parts (coils, contacts, mechanism components) held in stock for rapid replacement.
- Technical response within 24 hours; multilingual manuals in English, Russian, French and Arabic.
- Warranty: 18 months from delivery or 12 months from commissioning, whichever expires first.
TYPE TESTING
- Type tested to the applicable IEC standard - IEC 62271-100 for circuit breakers, IEC 62271-102 for earthing switches and disconnectors, IEC 62271-103 for load break switches.
- Verified for rated short-circuit breaking and making capacity, short-time withstand current, power-frequency and lightning impulse withstand, temperature rise, and mechanical endurance across the full rated operating sequence.
- Third-party certification from KEMA, ASTA, CESI or TUV available where the tender requires witnessed evidence.
VACUUM INTERRUPTER CONTROL (where applicable)
- Every interrupter is vacuum-integrity tested before assembly; vacuum degradation is the dominant failure mode in a VCB and is not visible externally once installed.
- Contact stroke, over-travel and contact wear allowance measured and recorded per pole.
- Interrupters sourced only from qualified manufacturers with batch traceability.
IN-PROCESS INSPECTION
- Insulating components partial-discharge tested before assembly.
- Mechanism spring force and charging characteristic verified against specification.
- Pole-centre distance and mounting interface dimensions checked against drawing - critical for retrofit interchangeability.
- Plating thickness on current-carrying contacts verified per batch.
ROUTINE TESTING - 100%, NO SAMPLING
- Power-frequency withstand voltage across the open contacts and to earth.
- Main circuit contact resistance measurement.
- Mechanical characteristic curve: closing time, opening time, contact bounce, and three-phase simultaneity.
- Operating mechanism function at minimum, rated and maximum control voltage - a unit that only operates at nominal voltage will fail during a real disturbance when station battery voltage sags.
- Auxiliary switch continuity and position signalling verification.
- Serialised routine test report issued with every unit.
TRACEABILITY AND SYSTEM
- ISO 9001 quality management system.
- Serial number traceability to vacuum interrupter batch, mechanism batch and insulation component batch.
- Test records retained for the warranty period and available on request.
ENVIRONMENTAL QUALIFICATION
Where the destination environment exceeds IEC reference conditions we qualify against it: elevated-ambient temperature-rise verification for Gulf service, salt-spray testing for coastal sites, and low-temperature operation verification with cold-rated lubricant for GOST 15150 climatic versions.
