Research on Mechanical Fault Analysis and Improvement Techniques of High-Voltage Disconnector Switches

With the continuous advancement of mechanization in modern society, the demand for electrical energy in daily life has significantly increased. To ensure that power supply meets this growing demand, the power system must operate with greater stability, safety, and real-time responsiveness. This highlights the critical importance of high-voltage disconnector switch quality during manufacturing.

Manufacturers must strengthen their awareness of this responsibility to ensure reliable operation of high-voltage transmission lines and reduce the frequency of failures. It is essential to recognize that disconnector switches are responsible for safely isolating electrical equipment under no-load conditions during emergencies. Therefore, a comprehensive analysis of existing mechanical faults is necessary, followed by targeted solutions to mitigate risks.

1. Common Defects and Fault Analysis

High-voltage transmission lines require regular maintenance, necessitating frequent operation of high-voltage disconnector switches to isolate power sources—ensuring the safety of maintenance personnel. However, due to inherent design and material flaws, mechanical faults remain the most common failure type. Investigations show that improper installation, inadequate commissioning, or mechanical corrosion often lead to excessive temperature in the conductive circuit, insulation cracking, and even severe safety incidents.

A particularly dangerous mechanical fault is the fracture of supporting porcelain insulators. This failure poses the highest risk and can lead to catastrophic consequences. The causes can be analyzed from several aspects:

• Material Quality Issues: Substandard insulator quality, due to poor manufacturing control, introduces serious safety hazards. Examination of fractured insulators consistently reveals internal impurities, micro-cracks, poor bonding quality, and in some cases, the absence of asphalt as a shock-absorbing layer.

• Design and Process Defects: Inherent design flaws, improper workmanship, or inadequate firing processes during manufacturing can result in weak joints between the insulator and flange, reducing service life and reliability.

• Environmental Degradation: Long-term exposure to harsh conditions—including strong electromagnetic fields, chemical corrosion, and weathering—accelerates aging.

• Seismic Impact: During earthquakes, intense vibrations may cause insulator fracture due to structural resonance or mechanical stress.

Another common fault is operational failure of the disconnector switch, where improper operation leads to incomplete opening or closing (misalignment), resulting in poor contact, increased resistance, overheating, and potential equipment damage. Contributing factors include:

• Design Flaws or Incorrect Material Selection: Inadequate structural design or unsuitable materials compromise performance.

• Severe Corrosion: Rotating components, typically made of metal, are exposed to outdoor environments. High humidity, lack of lubrication, and prolonged exposure accelerate corrosion, reducing operational flexibility.

• Failure of Electric Control Systems: Defective electrical components in motorized operating mechanisms can cause operational failure.

• Environmental Factors: Outdoor exposure subjects switches to rain, snow, and pollution. In recent years, severe smog and increased atmospheric humidity have exacerbated corrosion.

• Chemical Corrosion: Atmospheric dust and moisture react to form corrosive electrolytes. When deposited on switch surfaces, these substances cause electrochemical corrosion.

• Internal Design Weaknesses: Poor sealing allows moisture ingress. Inappropriate material selection—such as metals with low corrosion resistance—or inadequate anti-corrosion coatings further degrade performance. Combined with insufficient maintenance and inspection, these factors lead to severe mechanical deterioration.

2. Improvement Measures for Mechanical Faults

2.1 Manufacturing and Quality Control

Manufacturers must strictly adhere to design specifications during production, ensuring proper material selection and overall quality control. To address porcelain insulator fractures:

• Ensure that switch design meets technical and operational requirements.

• Strengthen quality control in production by sourcing high-quality raw materials.

• Partner only with reputable, technically qualified suppliers.

• Establish quality assurance agreements with suppliers, including on-site inspections and product testing.

• Strictly follow operational procedures during production; address any technical errors or defects immediately—never force operation.

2.2 Overheating Prevention

Overheating in conductive circuits poses a serious safety hazard. Effective countermeasures include:

• Adjusting contact insertion depth to ensure optimal contact.

• Maintaining clean contact surfaces or adopting self-cleaning contact designs.

• Installing temperature sensors to monitor for abnormal heating and trigger early intervention.

• Implementing live-line cleaning to enhance maintenance efficiency.

2.3 Corrosion Protection

As corrosion is a major contributor to mechanical failure:

• Apply regular lubrication to moving parts.

• Use stainless steel or other corrosion-resistant materials.

• Improve sealing to enhance water resistance.

• Ensure high-quality anti-corrosion coatings are properly applied.

2.4 Maintenance and Inspection

Regular inspection and timely repair are essential. However, maintenance must be meaningful—not merely routine or perfunctory. Superficial repairs waste resources and fail to ensure safe operation. Only thorough, condition-based maintenance can prevent unexpected failures.

3. Diagnostic Methods for Mechanical Faults

Different diagnostic techniques offer distinct advantages and limitations. Personnel should select methods based on actual conditions, combining approaches to achieve accurate fault detection.

• Ultrasonic Testing: Before installation, use ultrasonic inspection to detect cracks in porcelain insulators and prevent latent defects.

• Stress Monitoring: After installation, monitor whether insulators are under abnormal mechanical stress.

• Infrared Thermography: Detect localized overheating in circuits. If hotspots are identified, take corrective actions promptly.

• Motor Current Monitoring: Measure motor current during operation to assess switch performance and identify anomalies.

• Strain Gauge Measurement: Use resistance strain gauges to detect abnormal stress on insulators.

• Signal Analysis: Analyze motor current signals to evaluate the health of the drive system.

4. Conclusion

Only after all diagnostic checks confirm normal operation and the absence of safety hazards should the disconnector switch be put into service.

This paper analyzes common mechanical faults in high-voltage disconnector switches, including porcelain insulator fracture, abnormal stress, circuit overheating, operational failure, and metal component corrosion. Based on current technical challenges, targeted improvement and preventive measures have been proposed. By implementing these recommendations, maintenance personnel can enhance the prevention of high-voltage insulation failures, improve system reliability, and ensure the safety of operating staff.