Do you know what is the vacuum integrity and maintenance of vacuum circuit breakers?

The vacuum integrity and maintenance of vacuum circuit breakers are crucial for ensuring their safe and reliable operation. Here are the specific details:

Core Points of Vacuum Integrity

The vacuum in a vacuum circuit breaker refers to the fact that the contact parts of the circuit breaker are located in a vacuum container where the internal air has been evacuated to a vacuum state. During the closing and opening of the contacts, this provides a better arc-extinguishing effect. Vacuum is relative and refers to a thin gas space with an absolute pressure lower than one atmosphere. Absolute vacuum refers to a space with an absolute pressure equal to zero, which is an ideal vacuum and has not yet been achieved in the world. The degree of vacuum is expressed by vacuum degree, which is the absolute pressure value of the thin gas space. The lower the absolute pressure, the higher the vacuum degree. According to experiments, to meet the insulation strength of the vacuum interrupter chamber, the vacuum degree must not be lower than 6.6x10-2 (negative square) Pa. New vacuum interrupter chambers manufactured in factories are required to be below 7.5x10-2 (negative square) Pa.

Maintenance Strategies and Cycles

Regular inspection: During operation, a power-off inspection of the connection tightness of the terminal blocks is required every 500 operations (approximately 1/5 of the mechanical life).

Comprehensive maintenance: When the mechanical or electrical life is approaching its end, the inspection cycle should be shortened.

Key inspection items

Sealing performance test: Monitor the vacuum degree through a gas leakage detector to promptly identify damages in parts such as bellows and sealing surfaces.

Contact status: Inspect the wear of the contacts to ensure that the breaking performance is not affected.

Preventive measures

In addition to regular testing, the following measures can prevent the decline of vacuum degree:

1.Check mechanical parameters: Ensure that the mechanical parameters of the circuit breaker, such as contact overtravel, opening distance, and opening and closing speed, are within the specified range. Improper mechanical shock can damage the bellows of the arc extinguishing chamber, leading to gas leakage.

2.Keep clean: Keep the insulating rods and porcelain shells of the circuit breaker clean to prevent external flashover caused by surface contamination, which may affect the interior.

3.Standard operation: Avoid unnecessary frequent operations to reduce mechanical wear on the bellows.

4.Establish equipment files: Record the vacuum degree data of each test and predict the remaining life of the arc extinguishing chamber through trend analysis.

Summary

By strictly controlling the vacuum integrity and conducting scientific maintenance, vacuum circuit breakers can operate stably for a long time, meeting the power system's demand for high reliability.

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