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China VTD9-12D Indoor High Voltage AC Vacuum Circuit Breaker - Reliable Suppliers & Factory Solutions
Detail introduction
Due to the special advantages of vacuum circuit breakers, they are particularly suitable for frequent operations that require a rated working current, or for places where short-circuit currents are broken multiple times. The three poles of this circuit breaker are longitudinally fixed on the side mounted chassis, including isolation switches, circuit breakers, earthing switches, and operating mechanisms, forming a side mounted structure. Due to its characteristics of miniaturization, integration, modularization, low maintenance, and consistent appearance, it is particularly suitable for installation in confined spaces such as distribution rooms, prefabricated substations, underearth garages, etc.
Quality standard
Product quality assurance is based on continuous improvement of research, development, design, and production processes that meet all aspects of the quality system requirements. It fully complies with the latest versions or modified versions of the following standards, specifications, and guidelines, and is not limited to them.
| IEC62271-1 | High voltage switchgear and control gear - Part 1: Common technical requirements for AC switchgear and control gear |
| IEC62271-100 | High voltage switchgear and control equipment - Part 100: High voltage AC circuit breakers |
| GB1984 | AC High Voltage Circuit Breaker |
| GB/T11022 | Common Technical Requirements for High Voltage Switchgear and Control Equipment Standards |
| DL/T402 | High Voltage AC Circuit Breaker |
| JB/T3855 | High voltage AC vacuum circuit breaker |
Service Conditions
- Environmental temperature: - 25℃ ~ +40℃;
- Altitude: ≤ 1000m;
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Relative humidity:
Daily average relative humidity ≤ 95%
Monthly average relative humidity ≤ 90%
Daily average vapor pressure ≤ 2.2x10-3 MPa
Monthly average vapor pressure ≤1.8x10-3MPa; - Seismic grade: seismic intensity ≤ 8;
- The applicable location is free from dripping water, flammable and explosive hazards, chemical corrosive gases, and severe vibrations.
※Note: When the usage environment deviates from normal usage conditions, please consult with our company to determine.
Technical parameter
| Item | Unit | Parameter | |
| Rated frequency | Hz | 50/60 | |
| Rated voltage | kV | 12 | |
| Rated power frequency withstand voltage (1 minute, r.m.s) | Phase to phase and phase to earth | KV | 42 |
| Isolation fracture | 48 | ||
| Control and auxiliary circuits | 2 | ||
| Rated lightning impulse withstand voltage (peak) | Phase to phase and phase to earth | kV | 75 |
| Isolation fracture | 85 | ||
| Rated current | A | 630, 1250 | |
| Rated short-circuit breaking current (rm..s) | kA | 20, 25, 31.5 | |
| Rated short-time withstand current and time | kA/s | 20/4, 25/4, 31.5/4 | |
| Rated peak withstand current | kA | 50, 63, 80 | |
| Rated short-circuit making current (peak) | kA | 50, 63, 80 | |
| Rated breaking current of single/back-to-back capacitor group | A | 400(630)/400 | |
| Rated capacitor bank making current | kA | 2.5 ( fre.≤1000Hz) | |
| Rated handover (transfer) current | A | / | |
| Mechanical life | Times | 10000 | |
| Main circuit resistance of each phase | mΩ | ≤ 80, ≤ 70 | |
| Clearance between open contacts | mm | 9 ± 1 | |
| Contacting travel | mm | 5.5 ± 1 | |
| Contact closing bounce time | mm | ≤2 | |
| Three-phase asynchronous closing and opening | ms | ≤2 | |
| Average opening speed (contact just opened - 6mm) | m/s | 0.9 ~1.3 | |
| Average closing speed ( 6mm - contact just opened) | m/s | 0.4 ~ 0.8 | |
| Rated contact pressure | N | 2400±200 (20 - 25kA) | |
| 3100±200 (31, 5kA) | |||
| Opening time (at rated voltage) | ms | ≤ 45 | |
| Closing time (at rated voltage) | ms | ≤ 70 | |
| Rated operating sequence | O-0.3s-CO-180s-CO | ||
Technical characteristics
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Reasonable design and novel structure
The operating mechanism is integrated with the "five-prevention" interlocking mechanism, and modular design is adopted for components such as the (circuit breaker) solid-sealed pole and the earthing switch. These components are combined into a single unit through a common mounting frame.
The operating panel indicators are integrated with the primary circuit indicators, providing clear, simple, and easy-to-understand indications. The interlocking design is rationally integrated to form a "foolproof" operating procedure, making incorrect operations "impossible".
The operating panel indicators are integrated with the primary circuit indicators, providing clear, simple, and easy-to-understand indications. The interlocking design is rationally integrated to form a "foolproof" operating procedure, making incorrect operations "impossible".
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Miniaturization
Compared with air-insulated switches of the same model and specification, the device has a smaller volume, with a cabinet width of only 500 mm. It is a paragon of the new generation of miniaturized air-insulated switchgear.
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Less maintenance
The device uses maintenance-free vacuum (arc extinguishing chamber) switch (poles), which are virtually maintenance-free, have a long service life, and offer low operating costs.
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Visual Consistency
VTD9 circuit breaker, FTD9 load switch, and GTD isolating switch have identical external dimensions, facilitating the expansion and combination of switchgear cabinets.
Basic structure
The typical structure of the circuit breaker is shown in the figure below:

VTD9-12D
1. Upper terminal
2. Wall-through pole
3. Isolation switch
4. Operating mechanism (box)
5. Cable terminal
6. Earthing switch
7. Installation rack
8. (door opening) Interlocking board
9. (door closing) Interlocking board
10. Earthing switch operation (shaft) hole
11. Earthing switch on/off status indication
12. Energy storage status indication
13. Counter
14. Circuit breaker opening and closing status indication
15. Energy storage handle
16. Opening button
17. Closing button
18. Isolation switch on/off status indication
19. App Lock
20. Isolation switch operation (shaft) hole
Typical outline dimensions (fit) and structural diagram

| Rated current (A) | 630 | 1250 |
| Rated short-circuit breaking current (kA) | 20, 25, 31.5 | |
| Inter-phase distance (mm) | 210 | |
VTD9-12 (inter-phase distance P=210) outline dimension drawing of vacuum circuit breaker
(this drawing is for normal installation, but it can also be reversed)

| Rated current (A) | 630 | 1250 |
| Rated short-circuit breaking current (kA) | 20, 25, 31.5 | |
| Inter-phase distance (mm) | 210 | |
VTD9-12D (inter-phase distance P=210) outline dimension drawing of vacuum circuit breaker
(this drawing is for normal installation, but it can also be reversed)
Frequently Asked Questions (FAQ)
What are the main applications of the VTD9 vacuum circuit breaker?
Due to its vacuum technology, it is highly suitable for frequent operations requiring rated working current, or environments where short-circuit currents are broken multiple times. Its compact side-mounted structure makes it ideal for confined spaces like distribution rooms, prefabricated substations, and underground garages.
Which standards does this vacuum circuit breaker comply with?
This product fully complies with international and national standards, including IEC62271-1, IEC62271-100, GB1984, GB/T11022, DL/T402, and JB/T3855.
What are the environmental limits for normal service conditions?
The standard operating environment requires an ambient temperature of -25℃ to +40℃, an altitude of ≤ 1000m, daily average relative humidity ≤ 95%, monthly average relative humidity ≤ 90%, and a seismic intensity of ≤ 8. The location must be free from dripping water, flammable/explosive hazards, and chemical corrosive gases.
How does the miniaturization design benefit users?
With a cabinet width of only 500 mm, it has a significantly smaller volume compared to standard air-insulated switches of the same specification. This allows for highly space-efficient switchgear layouts.
Does this equipment require frequent maintenance?
No, the device utilizes maintenance-free vacuum poles (arc extinguishing chambers) which offer a long operational lifetime and very low maintenance requirements, substantially lowering overall operating costs.
Can the VTD9 and VTD9-12D circuit breakers be installed in reverse?
Yes, while the outline dimension drawings illustrate normal installation setups, the configuration can also be reversed depending on your installation requirements.

