Introduction to the Development, Application, and Characteristics of Permanent Magnet Vacuum Circuit Breakers

Table of Contents

• Principle

• Development of Permanent Magnet Mechanisms for Vacuum Circuit Breakers

• Development and Application of Permanent Magnetic Materials

• Characteristics of Permanent Magnet Vacuum Circuit Breakers

• Simple structure

• Environmental protection

• Stability

The permanent magnet operating mechanism adopts a brand new intelligent phase selection vacuum switch structure. When this structure works, there is only one main moving component, without the need for mechanical release or locking devices. It has few fault sources, high reliability, and a long service life, usually over 100000 times. At the same time, it controls the opening and closing phases to achieve synchronous control, thereby reducing the impact of overvoltage and inrush current on the system, reducing the investment in system protection, and improving the overall life of the system.

Principle

The principle of a permanent magnet mechanism is basically that a piece of iron has magnets and coils on both sides. When one side of the coil is energized, it will generate a greater magnetic force than the other side, driving the iron plate to move towards the side with the greater magnetic force. When the iron plate comes into contact with a magnet on one side, the coil loses power, and the iron plate is held by the magnet to maintain its position. The movement of both sides of the iron plate can drive the circuit breaker to open and close.

The principle of a permanent magnet operating mechanism is generally similar to that of an electromagnetic operating mechanism. The driving shaft is made of permanent magnet material, and there is an electromagnetic coil around the permanent magnet.

Under normal circumstances, the electromagnetic coil is not charged. When the switch is about to open or close, the principle of magnetic attraction or repulsion is used to drive the opening or closing by changing the polarity of the coil. Although this current is not small, the switch stores energy through a large capacity capacitor, which is discharged during operation to provide a large current. The advantage of this type of mechanism is its small size and fewer transmission mechanical components, so its reliability is better than that of the elastic operating mechanism.

Development of Permanent Magnet Mechanisms for Vacuum Circuit Breakers

Since the successful development of the first vacuum circuit breaker by GE in 1961, the technical level of vacuum circuit breakers has rapidly improved. Among them, with the development of new contact structures and materials, the breaking capacity of vacuum circuit breakers continues to improve. As a switching element for controlling and distributing electrical energy, vacuum circuit breakers are increasingly widely used in power systems and maintain a dominant position in the medium voltage field.

Due to the unparalleled characteristics of its vacuum arc extinguishing chamber, the electrical life of vacuum circuit breakers has greatly increased. With the continuous improvement of the technical level of the operating mechanism, its mechanical life has also jumped from the traditional 2000 cycles to tens of thousands of cycles. Due to the use of advanced technology products such as vacuum arc extinguishing chambers, the electrical life of vacuum circuit breakers is fully guaranteed. The mechanical lifespan and reliability of the operating mechanism in conjunction with it have become prominent issues affecting the comprehensive characteristics of vacuum circuit breakers.

One of the most basic performance requirements of switchgear is the reliability of the operating mechanism. The most prominent problems of medium voltage switchgear in China are the low reliability of the operating mechanism and insulation issues, which have a significant gap compared to developed countries. At present, a new generation of maintenance-free high-voltage switch products have been proposed and launched in developed countries.

Development and Application of Permanent Magnetic Materials

The emergence of the third generation rare earth permanent magnet material neodymium iron boron material has shaken many technical fields related to permanent magnet materials. The excellent magnetic properties of neodymium iron boron materials are unmatched by other permanent magnet materials, and their resources are abundant and cheap, so they are widely promoted and applied. The emergence of this new permanent magnet material has had a revolutionary impact on the industrial technology field and has been valued by countries around the world.

In recent years, the technology of permanent magnetic materials in China has also achieved rapid development, and the gap between China and Vanguard International Semiconductor Corporation countries in the world is shrinking. China is very rich in rare earth resources, with the largest reserves in the world. With the improvement of production technology and process, its price is also greatly reduced.

Although China has the production technology of permanent magnet materials, the application of permanent magnet materials in the operating mechanism of medium voltage vacuum circuit breakers is still blank. The new type of permanent magnet mechanism utilizes these new materials, processes, and principles to achieve low energy consumption and high reliability in the magnetic drive device of vacuum circuit breakers.

Characteristics of Permanent Magnet Vacuum Circuit Breakers

Simple structure

It can reduce a lot of workload in maintenance and upkeep. The overall structure adopts an oil-free structure, so there is no need for regular oil injection operations. This mechanical component is much less than traditional spring operated components, making maintenance operations very simple. The use of highly reliable and long-lived components has extended the maintenance cycle.

Environmental protection

Mainly using oil-free solid lubrication technology, this will not cause machine wear due to the lack of regular oil replacement, as well as a large amount of power consumption. These problems are solved through oil-free structure. The power consumption during operation has been reduced, which is approximately 20% of the power consumption of traditional bomb operation in the past. In terms of product design, when maintaining a closed state, we do not need the action of an electromagnet. We only need the magnetic force of a permanent magnet to maintain a closed state, without the need for continuous charging of the electromagnet, which plays a energy-saving role.

Stability

The oil-free structure will avoid various accidents caused by the depletion of lubricating oil. By simplifying the structure, mechanical components are reduced and the occurrence of mechanical faults is also reduced. The non-contact transmission device composed of high-performance permanent magnets avoids transmission failures and other faults.