High-Voltage Vacuum Tubes on Transformers

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The high-voltage vacuum tubes on transformers usually refer to the vacuum tubes in high-voltage vacuum circuit breakers. The following is a detailed introduction to them:

### Structure and Principle

- **Structure of Vacuum Tubes**: They are mainly composed of parts such as the outer shell, contact system, shielding cover, and bellows. The outer shell is usually made of insulating materials like ceramic or glass, possessing good vacuum sealing and insulating properties. The contact system is a key component of the vacuum tube, and materials like copper-chromium alloy are generally used, which have high melting points, high electrical conductivity, and anti-welding properties. The shielding cover is used to absorb the metal vapor and plasma generated by the electric arc and protect the insulating performance of the vacuum tube. The bellows play a role in connecting the moving contact and the operating mechanism while ensuring the vacuum degree of the vacuum tube.

- **Working Principle**: When the high-voltage vacuum tube receives an opening or closing instruction, the operating mechanism drives the moving contact to move inside the vacuum tube. When closing, the moving contact contacts the stationary contact and the circuit is connected; when opening, the moving contact separates from the stationary contact and an electric arc is generated between the contacts. Since the inside of the vacuum tube is in a high-vacuum state, the plasma in the electric arc quickly diffuses and is absorbed by the shielding cover, so that the electric arc is extinguished within a very short time, thus realizing the disconnection and connection of the circuit and avoiding the damage to the contacts caused by the electric arc and the damage to the equipment.

### Features - **Good Arc Extinguishing Performance**: In a vacuum environment, the electric arc is easy to extinguish. It has a strong arc extinguishing ability and can quickly cut off the circuit, effectively protecting the transformer and other equipment from the damage of short-circuit current.

- **Strong Insulating Performance**: The high vacuum degree inside the vacuum tube and the use of insulating materials endow it with good insulating performance, enabling it to withstand high voltages and reducing the risks of phase-to-phase short circuits and ground short circuits.

- **Long Service Life**: Since the contacts work in a vacuum environment and are not prone to oxidation and wear, they have a relatively long service life, reducing the maintenance and replacement costs of the equipment.

- **Small Size and Light Weight**: Compared with traditional oil circuit breakers and so on, the high-voltage vacuum tube has a compact structure, is small in size and light in weight, which is convenient for installation and maintenance and saves the space of the substation.

### Maintenance Points

- **Regularly Check the Appearance**: Check whether there are cracks, damages, discharge marks and other abnormal conditions on the surface of the vacuum tube. If there are problems, they should be replaced in time.

- **Check the Wear of Contacts**: Judge the wear of contacts by observing the degree of burning of the contacts, the contact area, etc. When the wear of the contacts exceeds a certain limit, it is necessary to replace the contacts or the entire vacuum tube.

- **Detect the Vacuum Degree**: Use professional vacuum degree detection equipment to regularly detect the vacuum degree of the vacuum tube to ensure that it is within the normal range. If the vacuum degree decreases, it may lead to a decline in the arc extinguishing performance and needs to be dealt with in time.

- **Check the Operating Mechanism**: Ensure that the operation of the operating mechanism is flexible and reliable, that all components are firmly connected, and that there are no phenomena such as looseness or jamming, so as to ensure the normal opening and closing of the vacuum tube.

How much is the cost of replacing the high-voltage vacuum tubes of transformers?

The cost of replacing the high-voltage vacuum tubes of transformers usually ranges from several thousand yuan to tens of thousands of yuan. The following is a rough cost analysis:

### Price of the Vacuum Tubes Themselves

- **Domestic Ordinary Type**: The price is generally around 1,000 - 3,000 yuan per piece.

- **Domestic High-Performance Type**: The price is approximately 3,000 - 5,000 yuan per piece.

- **Imported Brands**: They are relatively superior in quality and performance, and the price is usually between 5,000 - 10,000 yuan per piece.

### Labor Costs - **Regular Replacement**: If only the vacuum tubes are simply replaced, the labor cost is about 1,000 - 3,000 yuan.

- **Complex Situations**: If it involves complex processes such as the disassembly, installation and debugging of the transformer, the labor cost may increase to 3,000 - 5,000 yuan or even higher.

### Other Costs - **Detection Costs**: After replacement, relevant detections need to be carried out on the transformer, such as insulation detection, withstand voltage test, etc. The detection cost is about 1,000 - 2,000 yuan.

- **Transportation and Lifting Costs**: If it is necessary to transport the vacuum tubes or use lifting equipment to assist in the replacement, transportation and lifting costs may also be generated, which may be around 500 - 2,000 yuan.