VS1 & LZND Series: Standard Protection & High-Endurance Solutions
One portfolio covering the full spectrum of indoor medium-voltage switching. Choose the vs1 vacuum circuit breaker(ZN63) for standard 12kV–24kV distribution in KYN28 panels, or upgrade to the LZND Electric Repulsion VCB for ultra-fast switching and a mechanical life of 300,000 operations.
VS1 & LZND indoor vacuum circuit breakers for metal-clad switchgear
This series offers a unified platform for indoor medium-voltage protection, covering both standard distribution and severe industrial duty. It includes the industry-standard VS1 (ZN63) for general applications and the specialized LZND series for high-frequency switching, ensuring optimal performance in KYN28 and custom panels.
The standard VS1 models utilize a modular spring operating mechanism to deliver reliable switching for 12kV and 24kV utility networks. They are designed for cost-effective protection of feeders and transformers, with a mechanical life of up to 30,000 operations and short-circuit breaking capacity up to 31.5kA.
For demanding environments, the LZND models feature an advanced electric repulsion mechanism. This unique design separates normal closing from fault clearing, achieving an ultra-long life of 300,000 operations. It is the ideal maintenance-free solution for electric arc furnaces, mining hoists, and soft starters where standard breakers fail.
For a broader view of XBRELE’s vacuum circuit breaker solutions, please visit the vacuum circuit breaker pillar page .
Indoor VCB technical specifications & selection guide
Compare the technical parameters and dimensions of our Standard VS1 series and High-Endurance LZND series to select the right breaker for your switchgear.
VS1-12 technical overview
VS1-12 is an indoor vacuum circuit breaker with a three-phase AC 50 Hz rated voltage of 12 kV. It is used as the protection and control unit of power grid equipment and power equipment of industrial and mining enterprises, suitable for frequent operation under rated operating current or short-circuit conditions.
The breaker adopts an integral design of the operating mechanism and the interrupter/insulation body, and can be supplied as a fixed installation unit or combined with a special propulsion mechanism to form a withdrawable handcart unit.
The table below is derived from the VS1-12 technical parameter sheet and summarizes the main electrical ratings.
Main technical parameters — VS1-12
Values according to the VS1-12 medium-voltage vacuum circuit breaker data sheet.
| No. | Item | Unit | VS1-12 |
|---|---|---|---|
| 1 | Rated voltage | kV | 12 |
| 2 | Rated frequency | Hz | 50 |
| 3 | Power frequency withstand voltage (1 min) | kV | 42 / 48 |
| 4 | Lightning impulse withstand voltage (peak) | kV | 75 / 85 |
| 5 | Rated short-circuit breaking current | kA | 20 / 25 / 31.5 / 40 |
| 6 | Rated current | A | 630 / 1250 / 1600 / 2000 / 2500 |
| 7 | Rated short-time breaking current (effective value) | kA | 20 / 25 / 31.5 / 40 |
| 8 | Rated peak breaking current (peak value) | kA | 50 / 63 / 80 / 100 |
| 9 | Rated short-circuit making current (peak value) | kA | 50 / 63 / 80 / 100 |
| 10 | Rated short-circuit current duration | s | 4 |
| 11 | Mechanical life | operations | 20,000 |
| 12 | Power frequency withstand voltage of secondary circuit (1 min) | V | 2000 |
| 13 | Rated operating sequence | — | O – 0.3 s – CO – 180 s – CO |
Outline & mounting dimensions — VS1-12
Outline and mounting dimensions of VS1-12 indoor vacuum circuit breaker for KYN28-type metal-clad switchgear.
| Item | Symbol | Value (mm) | Note |
|---|---|---|---|
| Overall height | H | — | Overall height of breaker assembly |
| Overall width | W | — | Including phase spacing |
| Depth | D | — | Total depth inside switchgear cubicle |
| Mounting hole spacing (horizontal) | L1 | — | Handcart or fixed base bolt spacing |
| Mounting hole spacing (vertical) | L2 | — | To match switchgear frame |
| Mounting hole size | Φ | — | Diameter of mounting bolts |
LZND-12 High-Endurance VCB
The LZND-12 is a new generation indoor vacuum circuit breaker designed for severe duty applications. It features a unique electric repulsion compensation mechanism that separates normal load closing from short-circuit closing.
This innovative design significantly reduces mechanism size and power requirements while achieving an incredible mechanical life of 300,000 operations. It is the ultimate choice for frequent switching in electric arc furnaces, soft starters, and mining hoists.
The table below summarizes the key technical parameters of the LZND-12/630-20U model.
Main technical parameters — LZND-12
Values according to the LZND-12 electric repulsion vacuum circuit breaker data sheet.
| No. | Item | Unit | LZND-12/630-20U |
|---|---|---|---|
| 1 | Rated voltage | kV | 12 |
| 2 | Rated frequency | Hz | 50 / 60 |
| 3 | Power frequency withstand voltage (1 min) | kV | 42 |
| 4 | Lightning impulse withstand voltage (peak) | kV | 75 |
| 5 | Rated short-circuit breaking current | kA | 20 |
| 6 | Rated current | A | 630 |
| 7 | Rated short-time withstand current (thermal) | kA | 20 |
| 8 | Rated peak withstand current (dynamic) | kA | 50 |
| 9 | Rated short-circuit making current (peak) | kA | 50 |
| 10 | Rated short-circuit duration | s | 4 |
| 11 | Mechanical life | ops | 300,000 |
| 12 | Closing time / Opening time | ms | 60 / ≤40 |
| 13 | Control voltage | V | AC/DC 220 |
Outline & mounting dimensions — LZND-12
Compact installation dimensions for LZND-12 electric repulsion vacuum circuit breaker.
| Item | Value (mm) | Note |
|---|---|---|
| Overall Width | 480 | Compact width |
| Overall Depth | 451 | Including terminals |
| Overall Height | 380 | Pole top |
| Phase Spacing | 165 | (150/180/210 optional) |
| Mounting Hole (W) | 460 | Base width |
| Mounting Hole (D) | 286 | Base depth |
Protection, control & frequent switching solutions
Whether you need standard protection for distribution networks (VS1) or specialized control for heavy industry (LZND), our indoor VCBs integrate seamlessly with relays and interlocking systems to form complete metal-clad switchgear solutions.
Advanced protection schemes
Build coordinated protection for both standard and severe-duty applications using VS1 or LZND breakers combined with modern relays.
- Over-current and earth-fault protection for utility feeders
- Short-circuit protection up to 50kA (LZND peak withstand)
- Integrated CTs for protection and metering functions
- Reliable fault clearing for transformers and capacitor banks
Mechanism & operating options
Choose the operating mechanism that fits your duty cycle: standard spring for distribution or electric repulsion for frequent switching.
- VS1: Spring mechanism with motor/manual charging
- LZND: Electric repulsion mechanism for 300,000 ops
- Mechanical and electrical interlocks for safe operation
- Auxiliary contacts for SCADA feedback and interlocking logic
Switchgear & system integration
Designed for flexibility, our breakers fit into new panels or serve as high-performance upgrades for existing installations.
- Compatible with KYN28 12kV/24kV metal-clad switchgear
- Ideal for high-voltage soft starter cabinets (LZND)
- Fixed or withdrawable handcart versions available
- Custom terminal arrangements for seamless OEM integration
How XBRELE builds reliable VS1 & LZND vacuum circuit breakers
Behind every VS1 and LZND unit there is a controlled manufacturing flow – from vacuum interrupter inspection to routine testing – designed to ensure long-term reliability in metal-clad switchgear applications.
From vacuum interrupter to finished breaker
XBRELE manufactures the vacuum interrupter assemblies, mechanism and breaker body in a coordinated process. Each step is monitored and recorded for traceability of every VS1 and LZND circuit breaker.
- 01
Vacuum interrupter inspection
Vacuum interrupters are checked for contact stroke, over-travel, contact resistance and vacuum integrity before assembly.
- 02
Insulation & pole assembly
Interrupters are built into insulated pole units (VS1) or embedded poles (LZND) to provide stable dielectric performance in service.
- 03
Mechanism integration & adjustment
The operating mechanism (spring or electric repulsion) is assembled and adjusted so opening/closing speeds and bounce times remain within strict limits.
- 04
Handcart / fixed-frame assembly
Breaker poles and mechanism are mounted on a withdrawable handcart or fixed frame and matched with the KYN28 switchgear interface.
- 05
Routine testing & final inspection
Each breaker passes electrical, mechanical and dielectric tests before packing, with serial numbers linked to quality records.
Routine tests for every breaker
Electrical routine tests verify insulation level and switching performance of each pole.
Insulation & switching verification
- Power-frequency withstand tests between phases and to earth
- Impulse withstand tests on a sample basis according to project requirements
- Contact resistance measurement for each main circuit
- Mechanical operating tests for O / CO sequences at rated control voltage
Routine-test records can be supplied together with the delivery if required.
Mechanical reliability
- Verification of 30,000 (VS1) to 300,000 (LZND) mechanical operations
- Check of opening and closing speeds within specified limits
- Control of closing bounce time and pole synchronism
- Environmental checks for lubrication and low-temperature operation
Documentation & traceability
- Type-test reports and routine-test certificates for VS1 & LZND series
- Factory inspection records with serial-number traceability
- Outline drawings, wiring and terminal diagrams in digital format
- Recommended maintenance guidelines for substation and industrial users
FAT / QAP / ITP witness testing can be arranged for utility and EPC projects on request.
Global logistics for standard & high-performance VCBs
XBRELE delivers both standard VS1 breakers and specialized LZND units worldwide. We provide export-grade packing and technical support to ensure your indoor switchgear projects run smoothly.
Lead time & availability
We maintain stock of common VS1 components for fast assembly, while specialized LZND units are built to order.
- VS1 (Standard): 15–20 days lead time
- LZND (Custom): 25–35 days for production & testing
- Low MOQ for OEM panel builders
- Urgent air freight options for critical spares
Secure export packing
All breakers are packed to withstand long-distance transport, ensuring mechanism integrity upon arrival.
- Reinforced wooden crates with shock-absorbing foam
- Vacuum-sealed packaging for moisture protection
- LZND mechanisms secured with extra bracing
- Full shipping documentation (FOB/CIF/DDP) provided
Technical & project support
Our engineering team assists with integration into KYN28 panels and custom industrial cabinets.
- 2D/3D CAD models for panel layout design
- LZND Selection Guide for frequent switching duty
- Wiring diagrams & interlock logic support
- Remote commissioning assistance available
Frequently asked questions about VS1 vacuum circuit breaker
The answers below cover typical questions from panel builders, EPC contractors and utilities when selecting and applying VS1 indoor vacuum circuit breakers.
What are the typical applications of the VS1 indoor vacuum circuit breaker?
VS1 indoor vacuum circuit breakers are mainly used in metal-clad switchgear such as KYN28-12 / KYN28-24 panels for medium-voltage distribution systems.
- Incoming and outgoing feeders in 6–12 kV or 24 kV substations
- Transformer feeder bays and capacitor bank switching bays
- Industrial plant distribution boards and motor control centers
- Replacement of ageing oil or SF6 breakers in existing switchgear
Which standards does the VS1 vacuum circuit breaker comply with?
VS1 breakers are designed and type-tested according to international and national standards for high-voltage AC circuit breakers, typically including:
- IEC standard IEC 62271-100 (High-voltage switchgear and controlgear – AC circuit-breakers)
- Relevant national standards such as GB/T 1984 for AC high-voltage circuit breakers
- Project-specific utility or tender requirements where applicable
How should I select rated current and breaking capacity for a VS1 breaker?
Rated current and breaking capacity must be coordinated with the system short-circuit level and the load of the feeder or transformer.
- Choose 630 A, 1250 A or higher current according to busbar and feeder loading
- Select rated short-circuit breaking current based on calculated fault level at the panel
- Check making current (peak) and short-time withstand current with the switchgear supplier
- Ensure CT ratios and protection relay settings match the selected VS1 rating
For complex projects, XBRELE can review single-line diagrams and fault level calculations to help confirm the correct VS1 rating.
What control voltages and auxiliary circuits are available for VS1?
The VS1 spring operating mechanism can be supplied with different control voltages and auxiliary circuits to match the switchgear design.
- Common control voltages: DC110 V, DC220 V, AC110 V or AC220 V
- Auxiliary contacts for open/close status, spring charged indication and trip signals
- Terminals for shunt trip, closing coil and anti-pumping circuit
- Optional under-voltage trip and closing interlocks on request
What maintenance is recommended for VS1 indoor vacuum circuit breakers?
Compared with oil or SF6 breakers, VS1 vacuum circuit breakers require only limited routine maintenance, but periodic checks are still important.
- Regular visual inspection of insulation surfaces, shutters and earthing devices
- Checking mechanical operation, interlocks and racking mechanism
- Measurement of contact resistance and mechanism opening/closing times when needed
- Cleaning and lubrication according to the maintenance guidelines provided by XBRELE
For critical substations, condition-based monitoring and periodic diagnostic testing can be added to extend service life and improve reliability.
Is the VS1 breaker interchangeable with ABB, Schneider, Siemens or Eaton panels?
VS1 breakers are mainly designed for use in Chinese and international metal-clad switchgear such as KYN28-type panels, and can in some cases be adapted as a replacement in panels originally equipped with other brands.
- Mechanical interface (racking, shutters, fixed contacts) must match the original panel design
- Primary circuit dimensions and insulation clearances need to be checked against the existing busbar system
- Control wiring, auxiliary contacts and interlocks must be adapted to the panel’s schematic
- In many cases a dedicated retrofit study or adapter handcart is required
For any replacement of ABB, Schneider, Siemens, Eaton or other OEM breakers, XBRELE recommends providing panel drawings, photos and nameplate data so that a detailed compatibility check can be carried out before offering a retrofit solution.