Why is the volume of your vacuum circuit breaker so small while its service life is so long?

The reason why a vacuum circuit breaker can achieve both "small volume" and "long service life" lies in the outstanding performance of its core component - the vacuum interrupter. Let's explain this in detail from several key principles:

Why is the volume small? (Compact structure)

The "small volume" of the vacuum circuit breaker mainly results from the extremely high insulation strength of the vacuum as an insulating medium.

1. Vacuum is an excellent insulator: Under standard atmospheric pressure, air molecules are dense, and charged particles (electrons, ions) are prone to collide with gas molecules, forming a conductive path (i.e., an arc). In a high vacuum environment (typically below 10^-4 Pa), gas molecules are extremely scarce, and charged particles have almost no collision targets, making it difficult to form a conductive path. This means that the insulation strength of the vacuum gap is much higher than that of the same distance of air, oil, or SF6 gas.

Visual comparison: A 1-millimeter vacuum gap has a much higher withstand voltage value than a 1-millimeter air gap. Therefore, to withstand the same voltage, the gap distance required for the vacuum interrupter can be made very short (usually only a few millimeters to tens of millimeters).

vacuum interrupter

2. The structure is extremely compact: Due to the very small contact gap, the entire interrupter can be made very small. In contrast:

1) Oil-filled circuit breakers: Require a large amount of insulating oil and a complex oil tank structure.

2) SF6 circuit breakers: Require sufficient gas pressure and gas chamber space to maintain insulation and arc extinguishing capabilities.

3) Air circuit breakers: Require a longer arc path and arc arrestor plates.

Therefore, the core interrupter unit of the vacuum circuit breaker itself is very compact, laying the foundation for the miniaturization and intelligence of the entire switch cabinet (such as gas-filled cabinets, solid insulation cabinets).

Why is the service life long? (High reliability and durability)

"Long service life" mainly manifests in two aspects: electrical life (number of opening cycles) and mechanical life (number of operations).

The arc energy is extremely low, and the contact wear is small (the key to long electrical life).

1) Characteristics of vacuum arcs:

When arcs arc in a vacuum environment, the arc is not maintained by gas ionization, but is formed by the evaporation of the contact material into metal vapor. Since there are no air molecules to maintain and spread the arc in a vacuum, the vacuum arc is tightly confined to a very small, glowing point on the contact surface (called the cathode spot), which has an extremely high temperature but exists for a very short time (microsecond level) and travels rapidly on the contact surface.

2) Strong medium recovery strength:

3) When the alternating current passes through zero, the arc is instantly extinguished, and the metal vapor spreads rapidly in the vacuum space and quickly condenses, re-depositing on the contact surface and the shielding cover. This enables the insulation strength (medium recovery strength) of the vacuum gap to recover extremely quickly, effectively preventing arc re-ignition.

VTZ-24

4) Result: Due to the low arc energy and short burning time (usually only half a cycle), each opening cycle has very little electrical wear on the contact. A high-quality vacuum circuit breaker can easily achieve tens of thousands or even 100,000 or more full-capacity openings, while the contacts of traditional circuit breakers may be severely burned and require replacement after a few large current openings.

5) Sealed structure, maintenance-free (mechanical life and stability)

A. Isolated from the external environment: The vacuum interrupter is a completely sealed "black box". The contacts operate in a pure vacuum environment, completely unaffected by external factors such as humidity, dust, chemical corrosion, and altitude. This fundamentally eliminates faults caused by deterioration of the external insulation.

B. Simple operating mechanism: Due to the small contact gap, the required operating power is also small, and the operating mechanism (such as a spring mechanism) can be designed to be lighter and more reliable. This usually allows its mechanical life to also reach tens of thousands.

C. Special Contact Materials

The vacuum circuit breaker uses specially formulated copper-chromium (CuCr) and other composite materials as contacts. These materials possess the following characteristics:

High breaking capacity: Capable of effectively interrupting large currents.

High conductivity: Reduces heat generation during normal operation.

Low trip value: Reduces operational overvoltage and protects equipment.

Resistant to arc erosion: Further ensures electrical lifespan.

In summary, by leveraging the unique medium of "vacuum", the vacuum circuit breaker perfectly balances the conflicting demands of "miniaturization" and "long lifespan" that are often contradictory in traditional technologies. As a result, it has become the dominant technical solution in the medium-voltage field (particularly in the range of 12kV - 40.5kV).

hot sell product

VTZ-12 indoor phase-selective switching intelligent vacuum circuit breaker (Tongzhong Electric's exclusive model) is designed for indoor switchgear with a rated voltage of 12kV and AC 50/60Hz. It utilizes a permanent magnet operating mechanism and is suitable for specialized applications in various industrial and mining enterprises and power grids. The trolley unit can be used directly with the KYN28A-12 switchgear, directly replacing conventional three-phase integrated vacuum circuit breakers in existing switchgear.

vtz-12-series-indoor-phase-selective

This intelligent vacuum circuit breaker features a permanent magnet mechanism, a permanent magnet mechanism controller, and an intelligent processor. Three controllers, working with three independent permanent magnet mechanisms, enable phase-selective switching of three-phase systems. Furthermore, the intelligent processor features adaptive functionality, using feedback from voltage and current signals for synchronous calculations and issuing commands to enable the circuit breaker to switch on and off at any phase, meeting diverse application requirements.