Temperature control of energy-efficient oil-immersed transformers must balance insulation lifespan, operational efficiency, and energy efficiency standards. The core temperature parameters and management key points are as follows:

　　I. Key Temperature Limits

　　Top Oil Temperature

　　Maximum Limit: 95°C (in accordance with GB 1094.2 and DL/T 572-2010 standards), though it is recommended to stay below 85°C during actual operation.

　　Reason: Exceeding 85°C accelerates the aging of transformer oil (mineral oil), shortening insulation lifespan. For instance, the insulation aging rate may double with every 8-10°C rise in oil temperature.

　　Winding Temperature

　　Maximum Limit: 105°C (for Class A insulation materials, such as paper insulation).

　　Actual Operation: Winding temperatures are typically 10-15°C higher than top oil temperatures. If the top oil temperature is 85°C, winding temperatures may reach 95-100°C, necessitating that they remain below 105°C to prevent insulation damage.

　　Hot Spot Temperature

　　Definition: The temperature of the hottest point within the winding, which is a critical factor limiting transformer lifespan.

　　Standard: For every 6°C decrease in hot spot temperature, the insulation aging rate halves, doubling the lifespan. It is recommended that hot spot temperatures not exceed 140°C, as higher temperatures may generate bubbles, triggering insulation failures.

　　II. Temperature Optimization Strategies for Energy-Efficient Transformers

　　Efficient Cooling Design

　　Natural Oil Circulation: Driven by temperature differentials, suitable for small-capacity transformers but with lower heat dissipation efficiency.

　　Forced Oil Circulation: Utilizes oil pumps to accelerate oil flow, enhancing heat dissipation efficiency, but requires balancing oil flow speed (excessive speed may cause oil flow electrification, while insufficient speed reduces heat dissipation).

　　Smart Cooling Control: Dynamically adjusts the operation of cooling equipment (e.g., fans, oil pumps) based on load and ambient temperature to reduce energy consumption.

　　Application of Low-Loss Materials

　　High-Permeability Silicon Steel Sheets: Reduce iron core losses (iron losses), minimizing heat generation.

　　Low-Resistance Winding Materials: Such as copper foil windings, which lower copper losses and reduce heat production.

　　High-Temperature-Resistant Insulation Materials: Such as thermally modified insulating paper, which allows for higher hot spot temperatures (e.g., 110°C), extending lifespan.

　　Temperature Monitoring and Early Warning Systems

　　Fiber Optic Temperature Sensing Technology: Utilizes fluorescent fiber optic sensors to monitor winding hot spot temperatures in real-time, offering high precision and electromagnetic interference resistance, suitable for strong electromagnetic environments.

　　Wireless Temperature Monitoring Systems: Require no wiring and are easy to install, but involve regular battery replacements and higher maintenance costs.

　　Infrared Temperature Measurement: Non-contact measurement of surface temperatures with rapid response times, but unable to reflect internal temperature distributions.

　　III. Common Causes and Handling of Temperature Anomalies

　　Internal Faults

　　Turn-to-Turn Short Circuits: Cause localized overheating, accompanied by gas or differential protection activation.

　　Iron Core Multi-Point Grounding: Increases eddy currents, leading to overheating and potential oil ejection.

　　Handling: Immediately shut down the transformer for inspection and repair fault points.

　　Cooling System Failures

　　Fan Damage, Oil Pump Shutdown, Heat Dissipation Pipe Scaling: Result in reduced heat dissipation efficiency.

　　Handling: Regularly maintain cooling equipment and clean heat dissipation pipes.

　　Overload Operation

　　Short-Term Emergency Load: Allows hot spot temperatures to exceed 98°C but not 140°C.

　　Long-Term Overload: Accelerates insulation aging, necessitating load limitation or enhanced heat dissipation.

　　IV. Balancing Energy Efficiency and Temperature Management

　　Energy-efficient oil-immersed transformers reduce losses through optimized design, yet temperature control remains crucial. For example:

　　Energy Efficiency Grade Improvement: Transformers complying with GB 20052-2020 "Minimum Allowable Values of Energy Efficiency and Energy Efficiency Grades for Power Transformers" reduce heat generation by lowering no-load and load losses, thereby decreasing operating temperatures.

　　Whole Lifecycle Management: Integrates temperature monitoring data to optimize maintenance schedules, extend transformer lifespan, and reduce total lifecycle costs.