In-Depth Analysis of Temperature Ranges for Dry-Type Transformers

　　Dry-type transformers, as oil-free power equipment, rely heavily on precise temperature control to ensure insulation longevity, operational efficiency, and safety. Below is a systematic breakdown of standard temperature ranges, critical temperature limits, influencing factors, and temperature control measures, aligned with IEC/GB standards.

　　1. Standard Temperature Ranges (IEC/GB Standards)

　　Notes:

　　Class F Insulation: Common materials like Nomex® paper, rated at 155℃, permit a 100K temperature rise (i.e., winding temperature ≤140℃ at 40℃ ambient).

　　Class H Insulation: Materials such as silicone rubber or polyimide, rated at 180℃, permit a 125K temperature rise (winding temperature ≤165℃ at 40℃ ambient).

　　2. Critical Temperature Limits and Risks

　　3. Key Factors Influencing Temperature

　　Load Rate: Temperature rise under full load can be 3–5 times that at no load; adjust temperature control strategies based on load profiles.

　　Installation Environment:

　　Enclosed Spaces (e.g., switchgear rooms): Require forced ventilation or air conditioning.

　　Outdoor Environments: Demand sun-shielding and dust-proof designs (e.g., IP54 enclosure + axial fans).Cooling Methods:

　　Natural Air Cooling (AN): Relies solely on air convection, suitable for small-capacity transformers.

　　Forced Air Cooling (AF): Uses fans for forced ventilation, increasing capacity by 30–50% but increasing noise.

　　4. Temperature Control Measures and Protection Strategies

　　Temperature Sensors:

　　PT100 Platinum Resistors: Measure winding hotspot temperatures with ±0.5℃ accuracy.

　　Fiber Optic Sensing: Suitable for high-voltage windings, immune to electromagnetic interference.Protection Mechanisms:

　　First-Level Alarm (e.g., 110℃): Activates fans or prompts load reduction.

　　Second-Level Alarm (e.g., 130℃): Disconnects non-critical loads.

　　Trip Protection (e.g., 140℃): Cuts off main power supply to prevent escalation.Thermal Optimization:

　　Increase heat sink surface area (e.g., corrugated fin structures).

　　Use low-loss silicon steel (e.g., grain-oriented electrical steel) to reduce core losses.

　　5. Temperature Requirements in Typical Application Scenarios

6. Conclusion and Recommendations

　　Design Phase: Select insulation class based on load characteristics (Class F for standard scenarios; Class H for high-temperature/high-altitude applications).

　　Operation and Maintenance:

　　Monthly inspection of fans and filters; clean dust accumulation.

　　Semi-annual calibration of temperature sensor accuracy.Upgrades:

　　Adopt intelligent temperature control systems (e.g., PID-regulated fan speeds).

　　Explore new cooling technologies like evaporative cooling or heat pipes to further increase power density.By precisely controlling temperature ranges, dry-type transformers can achieve lifespans exceeding 30 years, providing reliable support for power systems.

　　This structured approach ensures clarity and compliance with international standards while addressing practical considerations for safe and efficient transformer operation.