The VS1-12 is a three-phase 50 Hz indoor high voltage vacuum circuit breaker rated 12 kV, designed as the protection and control unit of power networks and of power equipment in industrial and mining enterprises. It is intended for service that requires frequent operation at rated working current, or the repeated interruption of short-circuit currents. The breaker adopts an integrated design in which the operating mechanism and the breaker body share one frame, so it can be used either as a fixed installation unit or, with a dedicated racking mechanism, as a withdrawable handcart unit. Each of the three poles is carried on a compact insulated support within the frame, and the vacuum interrupter extinguishes the arc in a sealed ceramic bottle, so the insulation stays stable and the maintenance workload is minimal.
Model Designation
The type is marked as VS 1-12 / □ – □ YC:
- VS — indoor high voltage vacuum circuit breaker
- 1 — design number
- 12 — rated voltage, kV
- first □ — rated current, A
- second □ — rated short-circuit breaking current, kA
- YC — permanent-magnet operating mechanism
Example: VS1-12/1250-31.5 YC denotes a 12 kV indoor vacuum circuit breaker with 1250 A rated current, 31.5 kA rated short-circuit breaking current and a permanent-magnet operating mechanism.
Performance Advantages
- Double-stable permanent-magnet mechanism. Permanent magnets provide the holding force for both the closed and the open position, so latching is achieved without a long mechanical linkage. Compared with a conventional spring mechanism, the number of moving parts is greatly reduced and the transmission chain is shortened, which raises reliability and extends mechanical life.
- Vacuum interrupting chamber. The vacuum bottle extinguishes the arc, giving a long electric life with no fire or explosion risk and no routine maintenance of the interrupting medium. The low arcing energy and short burn time help the breaker clear fault currents within a few cycles.
- Integrated body and flexible mounting. The one-frame design lets the same breaker serve as a fixed unit or, with a racking truck, as a withdrawable handcart for metal-clad switchgear, supporting electric, manual and remote control with full interlocking.
Key Ratings Snapshot
| Item | Value |
|---|---|
| Rated voltage | 12 kV |
| Rated frequency | 50 Hz |
| Rated current | 630 / 1250 / 1600 / 2000 / 2500 A |
| Rated short-circuit breaking current | 20 / 25 / 31.5 / 40 kA |
| Mechanical life | 10000 operations |
| Standard | GB/T 1984 / IEC 62271-100 |
Technical Parameters
Service Conditions
- Ambient temperature: upper limit +40℃, lower limit -40℃
- Altitude: not above 1000 m (for higher altitudes the rated insulation level is raised accordingly)
- Seismic intensity: not above intensity 8
- Humidity: daily average not above 95%, monthly average not above 90%
- Environment: free from fire, explosion, serious pollution, chemical corrosion or violent vibration
Rated Voltage and Insulation Level
| No. | Item | Unit | Data |
|---|---|---|---|
| 1 | Rated voltage | kV | 12 |
| 2 | Rated frequency | Hz | 50 |
| 3 | 1 min power-frequency withstand voltage | kV | 42 / 48 (to earth / between phases) |
| 4 | Lightning impulse withstand voltage (peak) | kV | 75 / 85 (to earth / between phases) |
| 5 | Rated short-circuit duration | s | 4 |
| 6 | Mechanical life | operations | 10000 |
| 7 | Secondary circuit 1 min power-frequency withstand voltage | V | 2000 |
| 8 | Operating sequence | — | O – t – CO – t′ – CO |
Current and Breaking Capability by Rating
| Item | Unit | 20 kA | 25 kA | 31.5 kA | 40 kA |
|---|---|---|---|---|---|
| Rated short-circuit breaking current | kA | 20 | 25 | 31.5 | 40 |
| Rated current | A | 630, 1250 | 630, 1250 | 1250, 1600, 2000, 2500 | 1250, 1600, 2000, 2500 |
| Rated short-time withstand current (rms) | kA | 20 | 25 | 31.5 | 40 |
| Rated peak withstand current (peak) | kA | 50 | 63 | 80 | 100 |
| Rated short-circuit making current (peak) | kA | 50 | 63 | 80 | 100 |
Note: for the 20 kA and 31.5 kA ratings t = 0.3 s and t′ = 180 s; for the 40 kA rating t = 180 s and t′ = 180 s.
Standards
- Designed and tested to GB/T 1984 (AC high-voltage circuit breakers) and IEC 62271-100
- Manufacturing and inspection per DL/T 402
Installation & Wiring
Installation and Mounting
The VS1-12 can be installed as a fixed unit or, with a dedicated racking mechanism, assembled into a withdrawable handcart truck for metal-clad switchgear such as the KYN28 cubicle. The main circuit connects to the busbar and cable side through the static contacts of the truck, while the control and protection wiring is made through a secondary plug. The mechanism panel provides manual open and close buttons and position indication. The breaker frame and mechanism must be reliably earthed before energisation.
Outline and Installation Dimensions
Dimensions for the handcart (withdrawable) version on an 800 mm frame are given below; overall size varies with rated current and rated breaking current, and the approved drawing governs.
| Item | Dimension (mm) |
|---|---|
| Overall width | 648 |
| Base width | 652 / 681 |
| Overall height | 637 |
| Overall depth | 598 |
| Handcart wheelbase | 433 |
Dimensions by rating: handcart breakers are listed for 630 A (20 / 25 kA), 1250 A (25 / 31.5 kA) and 1600 A (31.5 kA); other ratings on request.
Applications
- Indoor MV switchgear in substations and in industrial and mining power distribution
- Feeder protection and control of motor loads that require frequent operation
- Distribution automation where repeated interruption of short-circuit current is expected
Selection & FAQs
Selection Guide
- Rated voltage and insulation level. Match the 12 kV rating to the system nominal voltage and check that the power-frequency and lightning impulse withstand values suit the busbar insulation level.
- Rated current. Choose from 630 to 2500 A on the maximum load current, allowing for temperature rise and busbar compatibility.
- Rated short-circuit breaking current. Select 20, 25, 31.5 or 40 kA from the prospective short-circuit current at the installation point, coordinated with the 4 s short-circuit duration.
- Operating mechanism and mounting. Confirm the double-stable permanent-magnet mechanism and choose fixed or withdrawable handcart to match the switchgear cubicle.
- Service conditions. Check the -40℃ lower temperature limit, altitude, seismic intensity, humidity and pollution level against the actual site.
- Compare neighbouring designs. For outdoor service see Outdoor Vacuum Circuit Breakers; for load switching see HV Load Break Switches.
FAQs
Q1: What does the type designation VS1-12/1250-31.5 YC mean?
VS is the indoor high voltage vacuum circuit breaker, 1 is the design number and 12 is the rated voltage in kV. The first figure 1250 is the rated current in amperes, the second 31.5 is the rated short-circuit breaking current in kA, and YC indicates the permanent-magnet operating mechanism.
Q2: What is the advantage of the permanent-magnet mechanism over a spring mechanism?
Permanent magnets hold the contacts in both the closed and the open position, so far fewer moving parts and a shorter transmission chain are needed than in a spring mechanism. This raises reliability and greatly increases mechanical life, which reaches 10000 operations.
Q3: Can the VS1-12 be used as a fixed or as a withdrawable unit?
Both. The mechanism and the body share one integrated frame, so the breaker can be installed as a fixed unit or fitted with a racking truck to form a withdrawable handcart for metal-clad switchgear such as the KYN28 cubicle.
Q4: How is the rated short-circuit breaking current selected?
It is chosen from the prospective short-circuit current at the installation point, in the 20, 25, 31.5 and 40 kA steps, and must be coordinated with the rated short-time withstand current and the 4 s short-circuit duration.
Q5: Is the breaker suitable for frequent operation or motor loads?
Yes. It is designed for service requiring frequent operation at rated current and repeated interruption of short-circuit current, and the permanent-magnet mechanism with a 10000-operation mechanical life supports heavy duty such as motor feeder control.
Q6: What data do I need to provide when ordering?
Please state rated voltage, rated current, rated short-circuit breaking current, short-circuit duration, operating mechanism, fixed or handcart mounting, and any special service conditions such as altitude or temperature.