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VS1-12 ZN63A-12 Indoor Vacuum Circuit Breaker (Fixed)
VS1-12 (ZN63A-12) indoor vacuum circuit breaker is a fixed-type three-phase MV circuit breaker rated at 12kV, designed for protection and switching in medium voltage distribution systems. Built to IEC 62271-100, this vacuum interrupter uses a sealed vacuum chamber for arc extinction, requiring no SF6 gas or oil. Rated from 630A to 3150A with short-circuit capacity up to 40kA, the spring operating mechanism supports both manual and motor-assisted charging. Widely deployed in utility substations, industrial motor feeders, and generator protection, this VCB is compatible with KYN28 switchgear and similar metal-clad assemblies across Middle East and African projects.
- Overview
- Applications
- Technical Data
- Services
- Quality Control
- Recommended Products
VS1-12 Indoor Vacuum Circuit Breaker - 12kV, 630A to 3150A
VS1-12, also designated ZN63A-12, is a three-phase indoor vacuum circuit breaker for 12kV medium voltage distribution. Built to IEC 62271-100, it is the most widely installed MV breaker across utility, industrial and infrastructure projects in the Middle East, Africa, Russia and Southeast Asia, and it is the standard breaker fitted to KYN28 metal-clad switchgear.
HOW VACUUM INTERRUPTION WORKS AND WHY IT MATTERS
When the contacts part, the arc burns in metal vapour inside a sealed ceramic chamber evacuated below 10-3 Pa. At the first natural current zero the vapour condenses back onto the contacts and dielectric strength recovers almost instantly. There is no oil to change, no SF6 to handle and no arc chute to clean.
The commercial consequences matter as much as the technical ones. No gas means no F-Gas reporting, no leak checking and no end-of-life recovery obligation - a growing consideration in EU and Eastern European tenders. No oil means no fire load and no oil disposal. And a maintenance-free interrupter suits markets where local servicing capability is limited, which is the most consistently reported constraint in Middle East and African electrical procurement.
SERVICE LIFE
Rated for 30,000 mechanical operations and 10,000 electrical operations at rated current. For a typical distribution feeder that is well beyond the life of the switchgear it sits in.
MECHANISM AND CONTROL
A spring stored-energy mechanism charges by motor (AC/DC 110V or 220V) with manual charging as backup, enabling an O - 0.3s - CO - 180s - CO auto-reclose duty. Closing and shunt-trip coils are specified to the station battery voltage. Auxiliary switch blocks up to 13NO13NC provide breaker position, spring-charged status and trip-circuit supervision signals to protection relays and SCADA.
An important qualification point: we function-test every breaker at minimum, rated and maximum control voltage. A breaker that only operates at nominal voltage will fail during a real disturbance, which is exactly when station battery voltage sags.
FIXED AND RETROFIT
VS1-12 is supplied as a fixed panel-mounted breaker or as the VSG-12 withdrawable handcart for KYN28 switchgear. Pole centre distance is 210mm at 12kV. Dimensional compatibility with VS1, VD4 and 3AH5 footprints allows direct replacement of aged breakers without modifying the cabinet - a significant advantage where the original panel manufacturer no longer supports the equipment.
MARKET FIT
The 12kV class serves 11kV networks across the Middle East and Africa and 10kV networks in Russia, CIS and Eastern Europe. Saudi Arabian supply is verified at 60Hz. Low-temperature versions with cold-rated mechanism grease and anti-condensation heating are available for CIS winter service.
PRIMARY APPLICATIONS
- Incomer and feeder protection in KYN28-12 metal-clad switchgear - the single largest application.
- Transformer primary protection on 10kV and 11kV distribution networks.
- Industrial motor feeder protection for large MV motors: pumps, compressors, crushers, mill drives.
- Generator circuit breakers in captive and standby power plants.
- Capacitor bank switching, where the breaker must handle high inrush and restrike-free interruption.
- Ring main unit feeder protection where fuse protection is inadequate.
- Renewable generation connection points on solar PV and wind collection networks.
- Bus-section and bus-coupler duty in double-busbar substations.
- Retrofit replacement of obsolete oil, air-magnetic and early vacuum breakers in aged switchgear.
RETROFIT AND REPLACEMENT MARKET
A large installed base across Africa, CIS and the Middle East runs on switchgear whose original breakers are no longer supported. Send us the existing model, pole centre distance and mounting dimensions and we will confirm interchangeability before you order. This is often far cheaper than replacing an entire switchboard, and it avoids the outage a full panel replacement demands.
REGIONAL FIT
- Middle East: 11kV networks. Saudi Arabia requires 60Hz verification and, for SEC projects, witnessed factory acceptance testing.
- Africa: 11kV networks with wide voltage fluctuation and limited local maintenance capability - maintenance-free vacuum interruption and stocked spare coils are decisive.
- Russia and CIS: 10kV networks, GOST R certification, GOST 15150 climatic versions for low-temperature sites.
- Eastern Europe: 10kV networks to EN 62271-100, with vacuum technology avoiding F-Gas obligations.
NOT SUITABLE FOR
Outdoor pole-mounted installation - specify ZW32-12. Systems above 12kV - specify VS1-24 or VSG-24. Applications where only load-break duty is required and fuse protection is acceptable, where a load break switch is more economical.
TECHNICAL DATA - VS1-12 / ZN63A-12
| Category | Item | Specification |
| Compliance | Standards | IEC 62271-100, GB/T 1984 |
| Electrical Ratings | Rated voltage | 12 kV |
| Rated insulation voltage | 12 kV | |
| Rated frequency | 50 Hz / 60 Hz | |
| Power-frequency withstand (1 min) | 42 kV | |
| Lightning impulse withstand (BIL) | 75 kV peak | |
| Rated normal current | 630 / 1250 / 1600 / 2000 / 2500 / 3150 A | |
| Short-circuit breaking current | 25 kA / 31.5 kA | |
| Short-circuit making current | 63 kA / 80 kA peak | |
| Short-time withstand current | 25 kA / 31.5 kA for 4 s | |
| Operating sequence | O – 0.3s – CO – 180s – CO | |
| Short-circuit duration | 4 s | |
| Endurance | Mechanical life | ≥30,000 operations |
| Electrical life at rated current | ≥10,000 CO operations | |
| Electrical life at rated short-circuit | 30–50 operations (depending on rating) | |
| Opening time | 30–60 ms | |
| Closing time | 40–80 ms | |
| Arcing time | ≤15 ms | |
| Operating Mechanism | Type | Spring stored-energy (VSG / CT03 series) |
| Spring charging motor | AC/DC 110 V or 220 V | |
| Manual charging | Provided as backup | |
| Closing coil | DC 110 V / 220 V | |
| Shunt trip coil | DC 110 V / 220 V | |
| Under-voltage release | Optional | |
| Auxiliary switch | F10 / FK10 series, up to 13NO+13NC | |
| Anti-pumping | Mechanical and electrical | |
| Mechanical | Pole centre distance | 210 mm |
| Mounting | Fixed panel-mount or VSG-12 withdrawable handcart | |
| Contact stroke | 11 ± 1 mm | |
| Contact over-travel | 3.5 ± 0.5 mm | |
| Weight (approx.) | 90 kg (630 A) – 140 kg (3150 A) | |
| Service Conditions | Ambient temperature | −30 °C to +55 °C |
| Altitude | ≤1000 m standard; ≤2000 m on request with derating | |
| Relative humidity | Daily average ≤95% |
OPTIONS
Withdrawable handcart configuration (VSG-12) | second shunt trip coil | under-voltage release | additional auxiliary contacts | operations counter | low-temperature grease for GOST 15150 climatic versions | anti-condensation heater | 60 Hz verification for Saudi Arabia | retrofit adapter plate for non-standard mounting
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.
