Temperature of dry-type transformers

Date: June 16, 2025 07:39:35

The temperature of dry-type transformer not only directly affects its operational performance and service life, but also closely related to the safety and stability of the entire power system. The following ENN Technology will be from the temperature standard, monitoring, control and other aspects of the detailed introduction of dry-type transformer temperature related knowledge:

I. Temperature standards for dry-type transformers

  1. ultimate temperatureThe insulation class of the dry-type transformer determines its limiting working temperature. Common insulation classes and their corresponding limiting temperatures are as follows:
    • Class F insulationThe limiting temperature is 155°C, and the average temperature rise of the winding during normal operation is 100K (K is the Kelvin temperature unit, and a temperature rise of 1K is equivalent to 1°C).
    • Class H insulationThe limiting temperature is 180℃ and the average temperature rise of the winding is 125K.
    • Class C insulationThe temperature limit can reach over 220℃, which is suitable for special occasions where high temperature resistance is required.
  2. Safe operating temperature range: In order to ensure the long-term stable operation of the transformer, the actual operating temperature is usually much lower than the limit value. In general, dry-type transformer winding temperature in the range of 80 ℃ - 100 ℃ operation, can maintain better performance and longer service life.

Second, the impact of temperature on the dry-type transformer

  1. Effects on insulation materials: For every 6°C rise in temperature, the aging of the insulation material is approximately doubled (i.e., the "6°C Law of Insulation Aging"). Long-term over-temperature operation will accelerate the aging and brittleness of insulating materials, reduce insulation performance, and ultimately may lead to winding short-circuit and other serious failures.
  2. Impact on load capacity: When the temperature is too high, the load capacity of the transformer will be reduced. In order to avoid over-temperature, it is necessary to reduce the load appropriately, otherwise it may trigger a vicious cycle, further pushing up the temperature and threatening the safety of the equipment.
  3. Effect on mechanical properties: High temperatures can cause the metal parts inside the transformer to expand and deform, destabilizing the mechanical structure and affecting its normal operation.

Third, dry-type transformer temperature monitoring and control

  1. Temperature monitoring
    • temperature sensor: Platinum resistors (PT100) are commonly used as temperature sensors and are installed in transformer windings, cores and other critical areas to collect temperature data in real time.
    • thermostat: The temperature signal transmitted by the sensor is processed and displayed, and some intelligent temperature controllers also have functions such as data logging and communication to support remote monitoring of the transformer temperature status.
  2. temperature control
    • natural air cooling: When the transformer temperature is low, it relies on natural air convection to dissipate heat.
    • Forced air coolingWhen the temperature of the winding reaches the set value (e.g. 100℃), the thermostat starts the cooling fan to accelerate the air flow and enhance the heat dissipation effect; when the temperature decreases to a certain level (e.g. 80℃), the fan stops automatically.
    • Over-temperature alarm and tripWhen the temperature exceeds the alarm threshold (e.g. 130℃), the thermostat issues an audible and visual alarm; if the temperature continues to rise to the danger threshold (e.g. 150℃), it triggers trip protection to cut off the transformer power supply and prevent the equipment from being damaged.

Fourth, reduce the dry-type transformer temperature measures

  1. Optimized thermal design: Reasonable design of the transformer's heat dissipation structure, increase the number of heat sinks or increase the area of heat dissipation, improve the efficiency of heat dissipation.
  2. Improvement of the operating environment: Ensure that the transformer is installed in a well-ventilated place, avoiding surrounding obstructions that affect air circulation; control the temperature and humidity of the operating environment, and install ventilation equipment or air conditioning when necessary.
  3. Reasonable load distribution: According to the rated capacity of the transformer and the actual operating conditions, the load is reasonably distributed to avoid long-term overload operation.
  4. Regular maintenance: Regularly clean the transformer surface and internal dust, check the operation of cooling fans and other cooling equipment to ensure that the cooling system works properly.
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