What are some common faults in high-voltage vacuum circuit breakers?

High-voltage vacuum circuit breakers are important protection and control devices in power systems. Common faults mainly involve the vacuum interrupter, operating mechanism, conductive circuit, and auxiliary components. The following is a detailed classification and explanation:

I. Vacuum Interruptor Related Faults

 

This is a core component of the circuit breaker, and faults in this component are usually quite serious:

Decreased Vacuum or Leakage

Symptoms: Reduced withstand voltage, decreased breaking capacity, potentially leading to internal flashover or explosion.

Causes: Manufacturing defects, bellows fatigue, material aging, mechanical damage.

Detection Methods: Power frequency withstand voltage test (most direct), vacuum degree tester (magnetic discharge method).

 

Excessive Contact Wear

Symptoms: Electrical wear of the contacts leads to changes in the contact gap, increased contact resistance, and abnormal temperature rise.

Causes: Frequent operation or contact material ablation after short-circuit current interruption.

 

Ceramic Housing Crack

Symptoms: Insulation failure, air leakage.

Causes: Mechanical stress, thermal stress, or improper installation.

 

II. Operating Mechanism Failure

Operating mechanism failure is a major component of field malfunctions, categorized into spring mechanisms, electromagnetic mechanisms, and permanent magnet mechanisms, etc.:

Failure to Operate (Refusal to Open or Close)

Mechanical Causes: Linkage jamming, pin detachment, spring fatigue or breakage, buffer failure.

Electrical Causes: Burned-out opening/closing coils (e.g., abnormal voltage, coils continuously energized), improper auxiliary switch switching, loose secondary wiring.

 

False Operation

Causes: Damaged secondary circuit insulation, DC system grounding, protection system false triggering.

 

Abnormal Opening/Closing Speed

Impact: Too slow a speed can easily cause arcing; too fast a speed can easily cause overvoltage or mechanical shock.

Causes: Changes in spring characteristics, defects in the oil buffer, poor lubrication of the mechanism.

 

Closing Bounce and Opening Rebound

Hazards: Bounce exacerbates contact burn-out; rebound may lead to reignition or failure to interrupt.

Causes: Inappropriate contact spring parameters, poor buffer design.

 

III. Conductive Circuit Faults

 

Increased Contact Resistance

Symptoms: Excessive temperature rise, potentially leading to thermal collapse.

Causes: Aging contacts, insufficient contact pressure, loose connections, or oxidation.

 

Flexible Connection Breakage

Symptoms: Partial discharge, overheating.

Causes: Fatigue aging, improper installation.

 

IV. Insulation Faults

External Insulation Flashover

Location: Bushings, supporting insulators.

Causes: Surface contamination, dampness, insufficient creepage distance.

 

Internal Insulation Faults

Location: Insulating tie rods, internal support components.

Causes: Moisture, cracks, aging.

 

V. Auxiliary and Control Circuit Faults

Microswitch/Auxiliary Switch Fault

Symptoms: Incorrect position signal, leading to control logic disorder.

 

Secondary Cable and Terminal Problems

Symptoms: Corrosion or loosening, causing false signals or failure to operate.

 

Energy Storage Motor Fault

Symptoms: Motor burnout, insufficient energy storage.

Causes: Motor aging, limit switch malfunction.

 

VI. Mechanical Characteristic Faults

 

Stroke and Overtravel Variations

Impact: Changes in opening distance and contact pressure affect breaking performance.

Causes: Improper adjustment, component wear.

 

Three-Phase Asynchrony

Hazards: May induce system overvoltage or breaking imbalance.

Causes: Mechanism adjustment errors or uneven wear.

 

Fault Diagnosis and Prevention Recommendations

 

Regular Maintenance and Inspection:

Vacuum Degree Testing: Combined with withstand voltage testing, especially during initial commissioning and after many years of operation.

Mechanical Characteristic Testing: Measure opening and closing time, speed, stroke, and synchronicity.

Circuit Resistance Testing: Promptly detect poor contact.

Insulation Testing: Includes insulation resistance and power frequency withstand voltage.

 

Condition Monitoring Technology:

Install online monitoring devices, such as contact life monitoring, mechanical vibration monitoring, and temperature rise monitoring.

 

Strengthen Operation Management:

Control the frequency of operation to avoid repeated interruptions of short-circuit current without timely inspection.

Maintain a clean and dry operating environment to prevent flashover and condensation.

 

Summary

High-voltage vacuum circuit breakers have high reliability, but faults are still concentrated in areas such as vacuum interrupter leakage, operating mechanism jamming/coil damage, and overheating of the conductive circuit. Regularly inspecting mechanical characteristics, circuit resistance, and insulation condition can detect most potential problems early. For older equipment or circuit breakers that are frequently operated, the inspection cycle should be shortened, and disassembly inspection should be performed when necessary.

Shaanxi Huadian vacuum circuit breakers offer precise opening and closing control, low operating power consumption, worry-free switching, and long-lasting operation. Inquiries are welcome.

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