What are the precautions for the inspection and maintenance of 10kV high-voltage switchgear?

10kV high-voltage switchgear is a critical piece of equipment in the power system, and its maintenance directly affects the safe and stable operation of the power grid. This work must be carried out in strict accordance with the principles of safety first and prevention foremost. The following are detailed precautions covering every step from preparation to completion.

I. General Safety Principles

 

♦Strictly implement the work permit system: All maintenance work on high-voltage equipment must be carried out with a work permit, clearly specifying the work content, safety measures, energized areas, and the person in charge.

 

♦Power outage, voltage testing, grounding, hanging warning signs, and installing barriers: These are the core technical measures to ensure safety and are indispensable.

Power outage: Disconnect the upstream and downstream power supplies of the switchgear, ensuring a clear disconnection point (e.g., pulling the trolley to the "Test/Isolate" position or opening the disconnect switch).

Voltage testing: Use a qualified voltage tester of the appropriate voltage rating to verify that there is no voltage on each phase of the incoming and outgoing lines.

Grounding: Close the grounding switch or connect a temporary grounding wire to prevent sudden power restoration.

Hanging warning signs and installing barriers: Hang signs such as "Do Not Close, People Working" and "Stop, High Voltage Danger" at adjacent energized cabinets and work sites. Temporary barriers should be installed when necessary.

 

♦Dedicated supervision: At least two people must be present during maintenance work, one of whom must supervise. Supervisors must not perform other duties and should constantly monitor the behavior of staff, promptly correcting any unsafe actions.

 

♦Use qualified tools and personal protective equipment: insulated gloves, insulated boots, voltage detectors, grounding wires, etc., must be inspected and certified on schedule. When operating and measuring, wear safety helmets and pure cotton work clothes.

 

II. Preparatory Work Before Overhaul and Maintenance

 

Technical Preparation:

Review equipment drawings, technical manuals, and the previous maintenance report.

Clarify the items, technical standards, and process requirements for this maintenance.

Conduct a hazard analysis and develop corresponding pre-control measures.

 

Tools and Materials Preparation:

Prepare a complete set of specialized tools (e.g., handcart crank), common tools, and instruments (e.g., switch characteristic tester, loop resistance tester, megohmmeter).

Prepare an appropriate amount of consumable materials, such as lubricating grease, cleaning agents, rags, bolts, etc.

Prepare new spare parts, such as closing coils, opening coils, auxiliary switches, indicator lights, etc.

 

On-site Preparation:

Obtain a work permit and complete the necessary approval procedures.

Confirm with operating personnel that safety measures have been correctly implemented.

Hold a pre-work meeting to explain the work tasks, safety measures, and precautions to all work members.

 

III. Key Precautions During Maintenance

 

1. Circuit Breaker (Vacuum Circuit Breaker) Section

Vacuum Interruptor Inspection:

Inspect the exterior for cracks and contamination.

Perform a vacuum degree test (generally using the power frequency withstand voltage method) to ensure the vacuum degree is within the acceptable range. This is the lifeline of the vacuum circuit breaker.

 

Mechanical Characteristic Test:

Use a characteristic tester to measure the opening and closing times, synchronicity, bounce time, travel, and overtravel. The data should conform to the manufacturer's specifications.

 

Main Conductive Circuit Inspection:

Inspect the moving and stationary contacts for burning or oxidation. Minor burning can be smoothed with fine sandpaper; severe burning requires replacement.

Measure Circuit Resistance: Use a circuit resistance tester to measure the main circuit resistance. The value should be acceptable and not significantly different from historical data. Excessive resistance indicates poor contact, which can lead to overheating.

 

Mechanism Inspection:

Spring Operating Mechanism: Check if the closing spring is fully charged, check for wear on the ratchet, latch, etc., ensure the transmission components are flexible, and lubricate appropriately.

Electromagnetic operating mechanism: Check that the closing contactor and the opening/closing core operate smoothly without jamming.

Check that the resistance values ​​of the opening and closing coils are normal and that the insulation is in good condition.

Check that the "open" and "close" indicators are correct and that the auxiliary switch of the mechanism switches is in place and reliable.

 

2. Disconnecting Switch/Trolley Section
Check that the contacts make good contact and that the pressure is appropriate. The contact springs should not be fatigued or deformed.

Check that the trolley guide rails are flat, that pushing and pulling is smooth and flexible, and that the positioning device is reliable.

Check that the mechanical and electrical interlocks between the trolley and the cabinet are complete and reliable. The "five-proof" functions are of paramount importance and must be verified one by one:

Prevent accidental opening or closing of circuit breakers.

Prevent opening or closing the disconnecting switch (pushing/pulling trolley) under load.

Prevent connecting (closing) the grounding wire (grounding switch) while energized.

Prevent closing the disconnecting switch (energizing) with the grounding wire (grounding switch) connected.

Prevent accidental entry into a energized compartment.

 

3. Current/Voltage Transformer Section
Check for any damage or oil leakage (oil-immersed type).

Check that the wiring terminals are secure.

Measure the insulation resistance and check that the secondary side is reliably short-circuited and grounded to prevent high voltage from an open circuit.

 

4. Cable Compartment Section
Inspect the cable ends for signs of discharge or overheating. Ensure the supporting insulation (supporting porcelain insulators) is clean and intact.

Check the live indicator sensor for proper function and monitor operation.

Clean away dust and ensure adequate insulation clearance.

 

5. Instrument and Relay Room (Secondary Circuit)

Check that all terminal block wiring is secure, especially the current circuit, to prevent open circuits.

Check that protective relays, instruments, indicator lights, and changeover switches are functioning correctly.

Perform a transmission test on the integrated protection device, simulating a fault, to verify that its protection functions (instantaneous trip, overcurrent, etc.) operate correctly and that signals are transmitted normally.

Check that the secondary line insulation is in good condition.

 

6. Busbar Room Check that the main busbar connection bolts are secure.

Check that the insulating support components (support insulators, through-wall bushings) are clean, free of cracks, and free of discharge marks.

Ensure that the distance to ground meets safety requirements.

 

IV. Post-Maintenance Cleanup

 

Comprehensive Cleanup: Inventory tools and personnel; remove all debris and materials remaining inside the cabinet and on-site.

 

Removal of Safety Measures: The work supervisor must confirm that all personnel have evacuated before ordering the removal of temporary grounding wires (or opening the grounding switch), and the removal of signs and barriers.

 

Pre-Power Restoration Inspection:

Confirm that all grounding wires have been removed and the grounding switch is open.

Confirm that the handcart is in the "Test" position and the circuit breaker is in the open state.

Confirm that the cabinet door is closed and locked.

Verify that the protection settings are correct.

 

Trial Operation:

Push the handcart from the "Test" position to the "Working" position, check for any jamming, and ensure the indicators are correct.

After obtaining permission from the dispatcher or operations supervisor, perform no-load opening and closing operations, observing whether all indicators and signals are normal.

 

Work Completion Procedures: Provide the operations personnel with a detailed explanation of the maintenance details, test results, and precautions, and return the work order.

 

Summary

 

The inspection and maintenance of 10kV high-voltage switchgear is a rigorous and meticulous task. Safety awareness must be maintained throughout the entire process, and technical standards must be strictly adhered to. Every standardized maintenance procedure provides strong protection for equipment and personnel safety. For uncertain or complex faults, timely reporting and professional technical support should be sought; blind operation should be avoided.

Shaanxi Huadian High Voltage Switchgear: Powered by technology and protected by quality. Our products are widely used in power plants, substations, industrial and mining enterprises, rail transportation, data centers, and other applications with extremely high power supply reliability requirements. Please contact us if needed.

Email:pannie@hdswitchgear.com.

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