Common Fault Diagnosis and Maintenance Guide for Dry-Type Transformers: Ensuring Stable Operation of Power Systems

Meta Description: This article provides a detailed analysis of common fault types, diagnostic methods, and maintenance strategies for dry-type transformers. It offers practical troubleshooting checklists and preventive maintenance recommendations to help users extend equipment service life and ensure the safe and stable operation of power systems.

Dry-type transformers, as core equipment in modern power distribution systems, directly affect power supply reliability. Although dry-type transformers feature high safety and low maintenance requirements, various faults may still occur during long-term operation. This article systematically analyzes the causes, diagnostic methods, and handling measures for common faults, providing practical reference for maintenance personnel.

1. Common Fault Types and Cause Analysis

1. Insulation Faults
   • Partial Discharge: Caused by aging insulation materials, moisture ingress, or defects.
   • Decreased Insulation Resistance: Resulting from dust accumulation, moisture intrusion, or excessive temperature.
   • Typical Symptoms: Abnormal noise, ozone odor, abnormal temperature rise.
2. Winding Faults
   • Winding Short Circuit: Caused by overload operation, insulation damage, or manufacturing defects.
   • Loose Connections: Resulting from thermal expansion/contraction or vibration.
   • Typical Symptoms: Three-phase current imbalance, increased noise, localized overheating.
3. Core Faults
   • Multi-Point Grounding: Caused by insulation damage or foreign objects.
   • Core Overheating: Eddy current losses due to damaged insulation between silicon steel sheets.
   • Typical Symptoms: Abnormal vibration, increased noise, rapid temperature rise.
4. Cooling System Faults
   • Fan Failure: Caused by bearing damage, motor burnout, or control circuit issues.
   • Blocked Air Ducts: Dust accumulation affecting heat dissipation.
   • Typical Symptoms: Abnormal temperature rise, unusual fan noise.

2. Fault Diagnosis Methods

1. Sensory Diagnosis
   • Listening: Using a stethoscope to detect abnormal vibrations and discharge sounds.
   • Visual Inspection: Observing discoloration, deformation, or discharge traces.
   • Smell Detection: Identifying ozone or burning odors.
2. Instrument Testing
   • Infrared Thermography: Detecting temperature distribution and identifying hotspots.
   • Insulation Testing: Measuring insulation resistance with a megohmmeter.
   • Partial Discharge Detection: Using specialized instruments to measure discharge levels.
   • Winding Resistance Test: Identifying winding connection issues.

3. Preventive Maintenance Strategies

1. Routine Inspection Items
   • Check temperature controller readings.
   • Clean casing dust and air ducts.
   • Inspect fan operation status.
   • Record operating temperature and load data.
2. Regular Maintenance Schedule
   • Monthly: Surface cleaning, fastener checks.
   • Quarterly: Insulation resistance testing, cooling system inspection.
   • Annual: Comprehensive preventive testing, including:
     • Winding DC resistance test.
     • Ratio and polarity test.
     • No-load and load loss tests.
     • Partial discharge detection.
3. Special Environment Maintenance
   • High Humidity Environments: Add heating devices, regularly check for condensation.
   • Dusty Environments: Increase air filter cleaning frequency.
   • Corrosive Environments: Use special anti-corrosion coatings.

4. Emergency Handling Guide

1. Immediate Shutdown Scenarios
   • Smoking or open flames.
   • Internal explosive sounds.
   • Rapid temperature rise exceeding limits.
   • Severe leakage incidents.
2. Scenarios Requiring Monitoring
   • Slight abnormal noises.
   • Slightly elevated but stable temperatures.
   • Minor partial discharge.

5. Service Life Extension Recommendations

1. Load Management
   • Avoid long-term overload operation.
   • Balance three-phase loads.
   • Reduce impact load frequency.
2. Environmental Control
   • Maintain well-ventilated installation spaces.
   • Control ambient temperature between -5°C to +40°C.
   • Maintain relative humidity below 90%.
3. Record Analysis
   • Establish complete operation records.
   • Regularly analyze operational data trends.
   • Implement predictive maintenance.

Conclusion

Effective fault diagnosis and maintenance management are key to ensuring the long-term stable operation of dry-type transformers. By implementing scientific preventive maintenance strategies, potential issues can be identified and resolved in a timely manner, significantly extending equipment service life and improving power supply reliability. Users are advised to establish comprehensive maintenance systems and provide regular professional training for maintenance personnel.