Research and Development of Vacuum Switch for Electric Locomotive

Research and Development of Vacuum Switch for Electric Locomotive
Core tips: Research and development of vacuum switches for electric locomotives Shishi Shi 1, Jinxi Zou 2 (1. Xi'an Jiaotong University, Xi'an 710049, Shaanxi, China; 2. Dalian University of Technology, Dalian 116024, Liaoning, China) Parameters, overall structure and. Because vacuum circuit breakers have strict restrictions on the installation height,

Research and Development of Vacuum Switch for Electric Locomotives Shishi Shi 1, Jinxi Zou 2 (1. Xi'an Jiaotong University, Xi'an, Shaanxi 710049, China; 2. Dalian University of Technology, Dalian 116024, Liaoning, China) Parameters, overall structure and.

Because the installation height of the vacuum circuit breaker is strictly limited, higher requirements are placed on the design and insulation of the vacuum interrupter.

The circuit breaker adopts the column type dry structure. The vacuum interrupter is installed in the epoxy resin shell. The external insulation adopts the vacuum cast silicone rubber insulating sleeve outside the epoxy barrel. The connection flange is made of SMC. The bottom is epoxy resin cast. Insulating rod adopts epoxy resin material, and the outer layer is bonded with formed silicone rubber insulating sleeve. Metal threads are embedded on both ends of the rod. The bending strength of the rod is higher than 1250kg/cm2. The protective cap is cast copper, except for sealing effect. In addition, it is also used as an upstream outlet. The switch part is fixed on the bottom plate by a fixed flange, and the upper bending strength is not less than 3000Nm. The lower outlet plate adopts the way of wrapping silicon rubber outside the copper row, and the sinking bottom adopts the wave shape to increase the creepage distance.

For the upper and lower insulation and tie rods, the power frequency withstand voltage is 85kV (1min) and the standard lightning impulse withstand voltage is 180kV. The key to fully passing the D-car vacuum switch is the vacuum interrupter, which must be higher than the normal power switch first. For more life, the open distance must be reduced to ensure the service life of the bellows. In order to ensure that the working voltage is higher than that of the general power switch under a small open distance, in the vacuum arc extinguishing design, the optimized design is adopted to make the internal electric field uniform and reduce the size, and at the same time the fine grain smelting copper-chromium contact material is used.

The use of a longitudinal magnetic field in the structural schematic can suppress the formation of anode spots and improve the breaking capacity. In addition, the longitudinal magnetic field contact has a lower wear rate. For this reason, the author uses longitudinal magnetic field structure contacts. The vacuum interrupter uses a ceramic skirt with a skirt to increase the creepage distance and ensure sufficient mechanical strength.

When other parts of the vacuum interrupter are in normal operation, they are not easily damaged. Only the fatigue life of the bellows determines the mechanical life of the vacuum switch. The bellows used in the vacuum interrupter are hydroformed bellows and sheet welded bellows. In order to ensure the mechanical life, a highly uniform diaphragm bellows with large diameter, multi-wavelength, welded stainless steel has been selected.

12.5kA short-circuit breaking current and power frequency 75kV and shock 150kV withstand voltage test, completely passed.

Due to the convenient source of compressed air in the locomotive, a cylinder-type operating mechanism was designed and used for this purpose, as shown. Its simple structure, small operating power, high transmission efficiency. The working principle of the operating organization is: After the 9/11 attacks on intelligence in the United States, the intelligence work in the United States has received fierce criticism. Public opinion mainly focuses on the four weaknesses of intelligence work: 1. People's analytical skills in linguistic tone are not enough to gather enough information to gather information from hostile organizations and informants in target countries. 2. There is a gap in the technical intelligence work and it is constantly expanding. Shown in the computer's decryption and analysis capabilities, especially the rapid transfer of the ability to intercept signals at sea, this information is encrypted e-mail, telephone and other communications monitored throughout the world. 3. There is a lack of cooperation among organizations that collect foreign intelligence, and there is a lack of understanding of the enemy’s intelligence activities and the situation of foreign terrorist forces on the mainland. 4. The problem of inconsistent relations among intelligence agencies in various countries has caused too much interference with the struggle against al-Qaeda’s international terrorist organizations, which have agencies in many countries.

This year, the United States’ intelligence work has highlighted three features: First, the budgetary expenses have risen sharply, increasing by 3 billion U.S. dollars, which has increased to 33 billion U.S. dollars; Submarines; The third is to strengthen the U.S. Security Agency employs far more mathematicians than any other unit.

The U.S. Central Intelligence Agency is an independent organization. The U.S. intelligence chief officer closes the electropneumatic valve and energizes the compressed air. The compressed air enters the transmission cylinder through the electropneumatic valve and the piston is moved upwards. The push rod transfers the vacuum interrupter. Contact is closed.

The electric air valve of the sub-gate is de-energized. Then it will close the gas path from the gas tank to the transmission cylinder, and at the same time, the compressed air in the transmission cylinder will be released into the atmosphere through the electric air valve. The piston will move down under the action of the sub-gate spring. The vacuum interrupter contacts are separated, and the buffer stoppers in the figure play a role in buffering, damping, and ensuring contact opening distance.

Protection When the compressed air pressure is insufficient, the electric air valve cannot be energized, and the operating mechanism cannot operate. When over-current, over-voltage, and short-circuit conditions occur, the electric air valve is de-energized and the breaker is opened.

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