Medium voltage vacuum circuit breaker tends to be specialized and multifunctional

Medium-voltage vacuum circuit breakers tend to be specialized and multi-functionalized.// With the continuous advancement of technology, vacuum circuit breakers are constantly undergoing innovation and development. Specialized and multifunctional vacuum circuit breakers have emerged .

Due to the extremely different breaking tasks faced by the circuit breaker, new dedicated circuit breakers have been continuously developed. For example, a large-capacity vacuum circuit breaker for generators (breaking current up to 6380 kA and above), a low overvoltage vacuum circuit breaker for breaking inductive loads, and a heavy-breakdown vacuum circuit breaker for switching capacitors. For frequent operation of circuit breakers for breaking electric furnaces and economical vacuum circuit breakers for general use (medium and small capacity).

For example, the 3AH series vacuum circuit breakers newly developed by Siemens are divided according to the application. There are 5 types of 3AH series products. Among the 5 types of circuit breakers, 3AH1 and 3AH3 type are standard type, high breaking current and 10,000 operating times; 3AH2 type is used for switching reactors and capacitors, and the number of operations is 60000. Times; 3AH4 type with frequent operation of the electric furnace, the number of operations 120,000 times, daily operation can be 100 times; 3AH5 type is economical, smaller capacity (12.525kV), the amount of large, cheap.

Another example is that five companies in Japan have developed low-voltage vacuum circuit breakers, of which Toshiba has achieved 7.2kV 40kA level (VL type), ranking above the level of major companies (usually 7.2kV20kA). Toshiba has also developed frequent vacuum circuit breakers, newly developed 24kV1250/2000A20kA and 36kV1250/2000A/12.5kA special frequent vacuum circuit breakers, which increase the number of operations from 100,000 times to 150,000 times, and about 10,200 times per day.

Another example is Holland Holland's vacuum circuit breakers are also divided into standard and special type. On the NVU type vacuum circuit breaker, the patented principle of first breaking and breaking is used to help prevent over-voltage due to interception and over-current.

As we all know, vacuum circuit breakers are generally two stations, that is, one by one, complete the closing and opening task, the current trend is to give vacuum circuit breakers more functions, such as one by one isolated one by one isolated ground. Siemens, Alstom, and Japanese companies all have such products.

The new NXAct type modular vacuum circuit breaker from Siemens has a multi-functional function and integrates breaking, isolation, grounding, and interlocking functions.

Alstom's VISAX switchgear has three circuit breakers (one for one, one for isolation). The 24kV vacuum circuit breaker developed by Hitachi in cooperation with Tokyo Electric Power Co., Ltd. has four stations (one for one, one for isolation and one for ground). This product has been used in 12 projects since December 1998 and will be used in the future. Expand the market. Japan's Mitsubishi also recently developed a multi-function vacuum circuit breaker that performs breaking, isolation, and grounding in a ceramic vacuum chamber. ABB also introduced a vacuum circuit breaker that combines breaking, measurement and protection.

In order to make the vacuum circuit breaker multifunctional, there are two approaches from the current product: one is to move or rotate the vacuum circuit breaker phase column after breaking, thereby forming isolation and grounding. Another approach is in the vacuum interrupter room. Isolation and grounding are accomplished by moving the contacts. The Siemens NXAct type modular vacuum circuit breaker has been completed to isolate and ground the phase poles after the opening, and the Alstom VISAX type vacuum circuit breakers used in the vacuum circuit breakers to complete the isolation task after the phase poles are opened. Hitachi and Mitsubishi both completed four stations in the arc-extinguishing chamber, one for each isolation and one for grounding, that is, the multifunction was completed in vacuum insulation.

1 Low-pressure chamber 2 - Pressure relief channel 3 - Circuit breaker unit 4 with isolation device 1 Core current transformer 5 - Capacitive voltage divider 6 - Grounding switch 7 - Cable VISAX type vacuum switchgear Cross section is VISAX type In the vacuum circuit breaker section, in the ''working'' position, each phase of the circuit breaker is in a vertical position. Once the circuit breaker is opened, each phase column can be rotated to the 'isolated' position.

Hitachi's four-station vacuum interrupter. As can be seen from the figure, in the vacuum arc-extinguishing chamber, the vertical movement of the movable contact is performed up and down to complete the integration, and then isolation and grounding are performed by rotation. Figure (a) also shows a general two-station vacuum interrupter for comparison.

Operating lever (for grounding) Cable 1 Busbar (a) Xibuyang (b) Internal structure The appearance and internal structure of the multi-functional vacuum interrupter is Mitsubishi's four-station vacuum interrupter. Among them, (a) shows the multifunctional vacuum arc extinguishing outdoor appearance, and (b) shows its internal structure.

As shown in (a), the multi-functional vacuum interrupter is composed of four ceramic tubes connected to the upper and lower parts of the conductor container. On the upper right side of the ceramic tube, equipped with an operating lever for breaking and isolation. On the upper left side of the ceramic tube, there is a grounding lever.

As shown in (b), in the lower right side ceramic tube, a contact that doubles as a break and isolation is provided, and after the break, the distance is further extended to be in an isolated state. On the upper end of the conductive rod of the lower left side of the (b) ceramic tube, a grounding switch contact is installed, and the circuit in the lower left ceramic tube and the lower right ceramic tube are connected by a soft connection.

Inside the upper right side ceramic tube, an insulating pull rod that transmits the operating force from the operating mechanism and the insulating circuit side and the operating rod side is installed. At both ends of the insulating pull rod, a moderate electric field shielding cover for increasing withstand voltage is installed, and bellows for pulling and telescoping the operating rod are respectively installed on the two upper ceramic tubes.

It is ABB's newest vacuum circuit breaker that integrates breaking, measuring and protection. It is based on VM1 type vacuum circuit breakers, equipped with Rogowski sensors on the electrodes, and uses electronic control to achieve protection functions. The preliminary protection scheme can achieve protection against a variety of over-current, ground fault currents and motor protection. The Rogowski coil is a toroidal air-core coil and has no magnet core, so it has no magnetic saturation, wide frequency response range, good linearity, compact size, safety, light weight, and long service life.

Permanent magnet mechanism solid sealed pole sensor as a disconnect switch withdrawing handcart Communication port Traditional I/O interface control and protection Structure diagram of eVM1 type integrated vacuum circuit breaker VM1 type vacuum circuit breaker is the ABB company following VD4 type vacuum circuit breaker New products launched a few years ago. Its structural features are the use of specially developed small vacuum interrupters, solid sealed poles and permanent magnet operating mechanisms. The new multi-function vacuum circuit breaker introduced this time is 12kV/1250A/31.5kA, and its model is eVM1 type.

Synchronous vacuum circuit breakers Synchronous vacuum circuit breakers are also called phased vacuum circuit breakers or controlled vacuum circuit breakers. The basic principle is to make the vacuum circuit breaker close or open () at the most favorable moment of voltage or current.

Compared with the common circuit breaker (CB), the synchronous circuit breaker's operating mechanism and phase column arrangement has the advantages of reducing the transient overvoltage load of the power grid, improving the power supply quality of the power grid, and improving the circuit breaker. The electrical life and performance; can simplify the grid design and reduce the overall system cost.

The maximum deviations of closing and opening are respectively *0.5ms and *0.1ms, which can only be achieved by the combination of the electronic device and the permanent magnet operating mechanism. Therefore, the presence of a permanent magnet operating mechanism makes it possible to synchronize circuit breakers.

It is a simple diagram of ABB's vacuum synchronous circuit breaker. Signal processing and timing devices are part of the synchronous circuit breaker, which is synchronized with the voltage and current waveforms. When it receives a signal, it is divided into one and altogether operation and decides when to send a signal to the following unit. The control device operates the phase column and must ensure that it is performed within the specified time deviation.

Each phase pole of the synchronous circuit breaker is equipped with a permanent magnet operating mechanism. Permanent magnetic actuators generally use electromagnetic operation, permanent magnet retention, electronic control and capacitor energy storage. It is completely different from spring operation mechanism, which greatly reduces the number of parts, improves reliability, and can be maintenance-free. The operating frequency of the permanent magnet operating mechanism is up to 100,000 times. The vacuum interrupter can operate 30,000 times at the rated current and 100 times under the short-circuit current. The permanent magnet operating mechanism is controlled by the electronic device and its energy consumption is less than 4W. The energy stored by the capacitor can provide 200s buffer time under the condition of the auxiliary power failure, and the capacitor reserves electric energy of about 200J and can provide 3000W impact energy. Electric appliances

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