Regular Inspection and Maintenance Guide for 6300kVA Dry-Type Transformers

In modern power systems, 6300kVA dry-type transformers are core components, crucial for ensuring safe and reliable operation. Transformer failures can not only interrupt power supply but also cause fires and other safety hazards, leading to significant economic and social losses. Therefore, regular inspection and maintenance of 6300kVA dry-type transformers is essential to maintain optimal performance and system reliability.

Core Operating Principles

Before performing any inspection or maintenance on 6300kVA dry-type transformers, strict adherence to electrical safety regulations is required. Key requirements include:

Follow the “power off, electrical test, grounding, and signage” procedures rigorously.

Ensure the transformer is fully disconnected from the power supply and reliably grounded.

Use qualified insulated tools, and ensure all maintenance is performed by professionally certified personnel.

Daily Inspections (While Energized)

Daily inspections can be conducted without powering down the transformer. They rely on observation, auditory cues, and smell to assess operational status. Key daily inspection points include:

Check the transformer's operating parameters, including current, voltage, load, frequency, and power factor for abnormalities.

Monitor the temperature of windings and key components to ensure normal operation. Verify the accuracy of temperature measurement instruments before use.

Inspect fan and cooling systems for normal operation, unusual vibrations, or abnormal temperatures.

Check lead connectors and cable busbars for overheating, using color changes and temperature-indicating paint as references.

Inspect on-load tap-changer contacts for overheating or irregularities.

Examine transformer appearance for dust, dirt, or contamination on windings, core, and other components.

Inspect insulation and windings for signs of carbonization, discharge marks, or cracks.

Listen for abnormal sounds or vibrations in the transformer and its accessories.

Detect any unusual odors, indicating overheating or insulation degradation.

Check the transformer casing for foreign objects, water ingress, and grounding issues causing resonance or discharge noises.

When excessive dust is observed, clean immediately to ensure airflow and prevent insulation breakdown. Focus on insulators, lower spacer bosses, and high-voltage winding surfaces. Use dry compressed air at 2–5 atmospheres to remove dust from ventilation ducts.

Regular Inspection and Maintenance (Monthly to Quarterly)

These inspections require the transformer to be powered off. Ensure all safety measures are implemented before starting. Key procedures include:

1. External Cleaning

Remove dust and debris from windings, leads, insulators, fans, and the core using dry compressed air or a vacuum cleaner. Avoid volatile solvents like gasoline or acetone to prevent insulation damage.

2. Tightening Inspection

Check all connecting bolts, clamps, and lead terminals for looseness. Retighten main circuit and grounding system connections with a torque wrench according to specifications. Loose connections are major causes of overheating and require special attention.

3. Insulation Inspection

Visually examine insulation on high- and low-voltage windings and leads for cracks, damage, or discharge marks. Address any issues immediately.

4. Fan System Inspection

Manually test all cooling fans via the thermostat function. Ensure fans start and operate smoothly, check for abnormal noises, and verify proper airflow direction. Clean fan blades and protective screens to maintain efficient heat dissipation.

5. Temperature Control System Verification

Check the thermostat display for accuracy and ensure over-temperature alarms, trips, and fan start/stop settings meet requirements. Use a handheld infrared thermometer as an auxiliary tool. Inspect PT100 platinum resistance probes and associated cables to verify proper operation of the temperature monitoring system.

Regular inspection and maintenance of 6300kVA dry-type transformers are essential for reliable and safe power system operation. By implementing daily checks, monthly or quarterly maintenance, and strict adherence to safety protocols, operators can prevent failures, reduce operational risks, and extend the service life of transformers.