Maintenance Best Practices for Epoxy Cast Dry-Type Power Transformers

1. Routine Visual Inspections

• Epoxy Encapsulation: Inspect windings and core for cracks, chips, or discoloration. Even small cracks can allow moisture or dust ingress, compromising insulation. If damage is found, contact a professional for repair (avoid DIY fixes, as improper handling may worsen the issue).
• Connections & Terminals: Ensure busbars, terminal blocks, and cable connections are tight, corrosion-free, and free of overheating signs (e.g., discoloration, melting insulation). Loose connections cause resistance buildup, leading to overheating and premature failure.
• Cooling System: For natural air-cooled (AN) units, check that airflow around the transformer is unobstructed (maintain a minimum 30cm clearance on all sides). For forced air-cooled (AF) units, inspect fans for debris, unusual noise, or failure—test fan operation periodically to ensure proper heat dissipation.
• Environmental Conditions: Verify the transformer’s installation area is clean, dry, and within recommended temperature limits (-20°C to +40°C for standard units). Avoid exposure to dust, oil mist, corrosive gases, or direct sunlight, as these accelerate degradation.

2. Electrical Testing & Diagnostics

• Insulation Resistance Test: Use a megohmmeter to measure insulation resistance between windings, and between windings and ground. A significant drop in resistance (compared to baseline values) indicates moisture absorption or insulation degradation. For epoxy cast transformers, the minimum acceptable resistance is typically ≥100MΩ (at 25°C).
• Turns Ratio Test: Confirm the transformer’s voltage ratio matches design specifications. Deviations may signal winding damage or short circuits.
• Temperature Rise Test: Monitor operating temperatures under full load using infrared thermometers or built-in temperature sensors. Excessive heat (exceeding 105°C for Class F insulation) indicates poor ventilation, overloading, or cooling system failure.
• Partial Discharge (PD) Test: For high-voltage units (≥10kV), PD testing detects internal insulation defects before they cause failures. Epoxy cast transformers are inherently low-PD, but aging or contamination can increase discharge activity.

3. Cleaning & Contamination Control

• Power Off & Lockout: Ensure the transformer is disconnected from the power supply and locked out to prevent accidental energization.
• Dry Cleaning: Use a soft brush or compressed air (low pressure, ≤5bar) to remove dust from windings, fins, and cooling fans. Avoid using water or chemical cleaners, as they may damage the epoxy coating or insulation.
• Corrosion Prevention: In coastal or corrosive environments, inspect metal components (e.g., core clamps, enclosures) for rust. Apply anti-corrosion spray if needed, and ensure the epoxy encapsulation is intact to protect windings from salt spray or chemical fumes.

4. Load Monitoring & Overload Prevention

• Use power monitoring tools to track load levels and avoid sustained overloads.
• If the transformer is consistently operating near or above rated capacity, consider upgrading to a higher-capacity unit (Leilang-Electric offers custom solutions to address load growth).

5. Documentation & Record-Keeping

• Inspection dates and findings.
• Test results (insulation resistance, temperature, turns ratio).
• Repairs, replacements, or modifications.
• Environmental conditions (temperature, humidity, dust levels).

• This documentation helps identify trends (e.g., gradual insulation degradation) and ensures compliance with industry regulations and warranty requirements.

6. Professional Maintenance for Critical Issues

• Cracks in the epoxy encapsulation larger than 1mm.
• Insulation resistance values below the minimum threshold.
• Unusual noise (humming, buzzing, or clicking) during operation.
• Overheating (surface temperature >110°C) or odor of burning insulation.
• Failed cooling fans or blocked airflow that cannot be resolved by cleaning.

Custom Epoxy Cast Transformers by Leilang-Electric

Our Customization Capabilities

• Voltage & Capacity: Primary voltages from 1kV to 35kV, secondary voltages from 220V to 10kV, and capacity ratings from 50kVA to 2000kVA. We accommodate both standard and non-standard voltage ratios for specialized applications.
• Design & Dimensions: Customize the transformer’s size, shape, and mounting configuration (floor-standing, wall-mounted, or compact) to fit tight spaces—such as underground utility rooms, rooftop installations, or industrial control cabinets.
• Insulation & Environmental Adaptations: For harsh environments (coastal, desert, chemical plants), we use high-grade epoxy resins with enhanced corrosion resistance and UV protection. For high-temperature settings, we upgrade to Class H insulation (180°C) for extended durability.
• Cooling Systems: Choose between natural air cooling (AN) for low-noise, low-maintenance needs or forced air cooling (AF) for high-load applications requiring enhanced heat dissipation.
• Certifications & Compliance: All custom transformers meet international standards (IEC 60076, ANSI/IEEE C57.12.01, GB/T 1094) and can be certified to UL, CE, or other regional requirements for global projects.

Why Choose Leilang-Electric for Custom Transformers?

• Expert Engineering: With over 15 years of experience in transformer manufacturing, our team combines technical precision with industry insights to optimize every custom design. We consider load profiles, environmental conditions, and long-term reliability to deliver solutions that exceed expectations.
• Uncompromising Quality: We source premium materials—high-purity epoxy resin, cold-rolled silicon steel cores, and corrosion-resistant components—to ensure durability. Each custom transformer undergoes rigorous testing (insulation resistance, short-circuit withstand, temperature rise) before delivery.
• Flexibility & Speed: We understand project timelines are critical. Our streamlined production process allows us to deliver custom transformers within 4–8 weeks (depending on complexity), without sacrificing quality.
• Lifecycle Support: Beyond delivery, Leilang-Electric provides comprehensive after-sales service—including maintenance guidance, technical support, and spare parts supply. Our team can also assist with on-site inspections and repairs to keep your custom transformer operating at peak efficiency.