Repair and maintenance of dry-type transformers

Temperature Monitoring: Check winding temperature (normal range for Class F insulation ≤130℃), ambient temperature not exceeding 40℃, and monitor whether the cooling fan automatically starts and stops (starts at ≥100℃, stops at ≤80℃).

Visual Inspection: Observe the winding surface for discoloration, cracks, or carbonization marks; check for rust or loosening of the core and metal parts; and check for deformation or dust accumulation in the casing.

Sound and Vibration: Listen for uniform operating sound, absence of discharge sounds or metallic clanging sounds, and abnormal vibration.

Regular Maintenance

1. Monthly Maintenance:

Cleaning and Dust Removal: Use dry compressed air or a soft brush to remove dust from the windings, core, and fan.

Check Terminals: Tighten high and low voltage cable joints to prevent overheating due to poor contact.

Fan Test: Manually start the cooling fan to confirm normal operation.

2. Quarterly Maintenance:

Insulation Resistance Test: Use a 2500V megohmmeter to measure the winding-to-ground insulation resistance (standard value ≥100MΩ).

Grounding System Check: Ensure grounding resistance ≤4Ω.

1. Tightening Inspection: Retighten all bolts (core clamps, winding supports, etc.).

2. Annual Maintenance:

Comprehensive Cleaning and Inspection: Thoroughly remove internal dust and check for aging or peeling of the winding insulation.

Insulation Aging Assessment: Perform partial discharge testing or dielectric loss angle testing (tanδ) on transformers that have been in operation for more than 5 years.

Protection Device Calibration: Calibrate the temperature controller, over-temperature alarm, and tripping functions.

Ventilation Management: Ensure unobstructed airflow around the transformer to prevent excessive temperature rise due to poor ventilation; install filters at the bottom ventilation holes and replace them regularly.

Installation Environment: Keep the environment dry and well-ventilated, avoiding corrosive gases or dust; dehumidify in humid environments.

Safe Operation: Before maintenance, always disconnect, test for, and discharge voltage, and post warning signs; use insulated tools and wear protective equipment.

Records and Precautions

Record Management: Record detailed data for each maintenance session (temperature, insulation resistance, etc.) and analyze trends.

Regular Rust Removal: Prevent core corrosion to avoid increased losses and decreased efficiency.

The above measures, based on industry standards and practical experience, can effectively prevent faults such as winding overheating and insulation deterioration. If serious problems are found (such as partial discharge or insulation breakdown), contact the professional manufacturer for assistance.