What are the maintenance items and quality standards for high-voltage vacuum circuit breakers?

The maintenance of high-voltage vacuum circuit breakers is a critical maintenance task, essential for ensuring the safe and stable operation of the power system. The maintenance procedures and quality standards typically follow national and industry standards (such as DL/T 403, DL/T 593, etc.) and the technical documentation provided by the equipment manufacturer. The following is a systematic summary:

I. Maintenance and Repair Items

1. Preparation

Obtain work permits and implement safety measures.

Check the equipment's historical defect records.

Prepare specialized tools, instruments, and spare parts.

 

2. Visual and General Inspection

Inspect the circuit breaker's outer surface, insulators, and support structures for damage, cracks, discharge traces, and severe contamination.

Check if the operating mechanism housing is properly sealed and free from water ingress, moisture, and corrosion.

Check all connecting bolts and fasteners for looseness.

Check if the opening and closing indicators are correct and clearly visible.

 

3. Vacuum Interrupter Inspection and Testing (Core Component)

Visual inspection: Check the glass or ceramic casing for cracks, abnormal luster (metal deposition), and oxidation or discoloration of internal parts.

Vacuum level testing: Perform quantitative measurement using a dedicated vacuum level tester (such as the magnetron discharge method), or perform qualitative assessment using the power frequency withstand voltage method.

Main circuit DC resistance test: Measure the DC resistance of the conductive circuit of each phase when the circuit breaker is in the closed position.

 

4. Operating Mechanism Inspection and Maintenance

Spring Operating Mechanism:

Check the springs for corrosion and cracks, and verify that the energy storage state is normal.

Check the wear of transmission components such as ratchets, pawls, and gears, and apply lubricating grease.

Check whether the pre-tension or length of the closing spring and opening spring meets the manufacturer's specifications.

Check the operation of the energy storage motor and measure its operating current and voltage.

Electromagnetic Operating Mechanism:

Check the closing coil and opening coil for overheating and burning, and measure their DC resistance.

Check that the iron core and push rod move smoothly without jamming.

Check that the auxiliary switch is properly switched and has good contact.

Permanent Magnet Mechanism:

Check the status of the control unit power supply and capacitor bank.

Test the holding characteristics of the bistable magnetic system.

Check that the position sensor is working properly.

 

5. Mechanical Characteristics Testing

Opening and Closing Time: Measure the time from the issuance of the command to the completion of contact movement.

Opening and Closing Speed: Measure the initial opening speed, initial closing speed, and average speed (as required by the manufacturer).

Opening and Closing Synchronicity: Measure the time difference between the opening and closing of the three-phase contacts.

Contact Gap and Contact Travel (Over-travel): Measure the travel parameters of the contacts.

Opening and Closing Coil Operating Voltage: Measure the minimum reliable operating voltage and the operating performance at the rated voltage.

Mechanical Operation Test: Perform several opening and closing operations at the rated operating voltage to check the reliability and consistency of the operation.

 

6. Secondary Circuit and Auxiliary Component Inspection

Check that all wiring terminals are secure and that the cables are undamaged.

Check that the auxiliary switches, microswitches, and limit switches operate accurately and reliably.

Check that the heaters and lighting are working properly.

Measure the insulation resistance of the secondary circuit.

Check that control functions such as anti-reclosing and incomplete phase protection are working correctly.

 

7. Insulation Performance Test

Measure the insulation resistance between the main circuit and ground, and between the contacts (using a 2500V or 5000V megohmmeter).

Perform AC power frequency withstand voltage tests between the main circuit and ground, and between the contacts (according to the regulations, paying attention to the pressure-free value for vacuum interrupters).

 

II. Main Quality Standards

 

 

Project	Quality Standards
Vacuum interrupter	1. Vacuum level: Must be better than the value allowed by the specifications (e.g., 10^-4 Pa level), or pass the power frequency withstand voltage test (e.g., 42kV/1min) without flashover or breakdown. 2. Appearance: No cracks, no large amounts of metal deposits (milky white), and no oxidation or discoloration of internal parts. 3. DC resistance: ≤ Manufacturer's specified value (usually in the micro-ohm range, such as 25-40 μΩ), and the difference between the three phases should generally not exceed 20%.
Mechanical characteristics	1. Time, Speed, and Synchronization:  Compliant with manufacturer's technical specifications. Typical reference values: Closing time difference ≤ 2ms, opening time difference ≤ 2ms; closing time ≤ 100ms, opening time ≤ 50ms (specific values ​​vary significantly depending on the model). 2. Contact Gap and Overtravel: Within the manufacturer's specified tolerance range (typically contact gap tolerance ±1mm, overtravel tolerance ±0.5mm).
Operating mechanism	1. Spring mechanism: Energy storage is smooth and without jamming; motor current is normal; springs show no permanent deformation; shaft and pin wear is within acceptable limits. 2. Electromagnetic mechanism: Coil resistance conforms to factory specifications; the iron core moves freely; the minimum operating voltage for opening and closing is between 30%-65% of the rated voltage (opening) and 80%-110% (closing). 3. Number of operations: Under rated voltage, continuous operation ≥5 times, with accurate and reliable operation.
Insulation performance	1. Insulation resistance: The overall insulation resistance is generally required to be ≥ 3000 MΩ (measured with a 2500V megohmmeter). 2. Power frequency withstand voltage: The test should pass according to the specified values ​​in the regulations (e.g., 95kV/1min for a 40.5kV circuit breaker to ground), without flashover or breakdown.
Secondary circuit	1. Insulation resistance: Measured with a 500V megohmmeter, generally ≥ 10 MΩ. 2. Components and wiring: Auxiliary switch operates reliably; wiring is secure; anti-tripping and other functions are verified to be correct.
Overall assembly	1. All bolts and fasteners have been tightened to the manufacturer's specified torque values. 2. The transmission components are well-lubricated and operate smoothly without jamming. 3. The enclosure is well-sealed, with no water leakage, and the dustproof and moisture-proof measures are effective. 4. The switching indicator is in complete agreement with the mechanical position.

 

III. Key Acceptance Points After Maintenance

Data Compliance: All test data meets the manufacturer's technical standards and industry regulations.

Reliable Operation: Both manual and electric operations are flexible, accurate, and free of abnormal noises.

No Leakage: There is no leakage in oil-filled (buffer) or gas-filled components.

Clear Labeling: The open/close indicator, energy storage indicator, and secondary terminal markings are clear and correct.

Complete Documentation: The maintenance report and test records are complete, and the data is accurate.

 

Important Notes:

Maintenance work must be performed by qualified professionals and strictly adhere to safety procedures.

The vacuum interrupter is a maintenance-free component, but its vacuum level must be checked regularly. If a vacuum failure is confirmed, the entire unit must be replaced; it should not be disassembled or repaired by unauthorized personnel.

The technical manual provided by the manufacturer is the highest priority standard. In case of conflict with general standards, the manufacturer's standard shall prevail (unless the manufacturer's standard is lower than national/industry standards).

For circuit breakers in good condition, the maintenance cycle can be extended or shortened based on condition assessment (e.g., online monitoring data, number of operations, operating environment).

Through the above systematic maintenance and strict quality control, the high-voltage vacuum circuit breaker can be ensured to be in good working condition, guaranteeing the reliable operation of the power grid.

 

Shaanxi Huadian vacuum circuit breakers feature precise opening and closing control and low operating power consumption.  From raw materials to finished products, we implement lean management throughout the entire process. They can easily achieve remote monitoring and automated management, assisting you in building an intelligent power distribution network. Inquiries are welcome.

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