The safe operation and service life of dry-type transformers depend on the safety and reliability of the winding insulation of dry-type transformers. The temperature of the winding exceeds the insulation endurance, and insulation damage caused by temperature is one of the main reasons why dry-type transformers cannot operate normally. Therefore, monitoring and alarm control of the working temperature of dry-type transformers are very important.
Because the construction of dry-type transformers starts from the inside and outside, they consist of iron cores, low-voltage coils, and high-voltage coils. The heat source is the iron core and low-voltage coil, while the high-voltage coil on the external surface has low heat due to low current. Therefore, the cooling effect of dry-type transformers and air conditioners is not good when using ordinary axial fans.
When manufacturing dry-type transformers, dedicated cooling pipes were left behind. Dry type transformers can only achieve the expected results by using special temperature control devices.
To meet the requirements of unmanned substations, it is recommended to install an air-cooled temperature control system on the existing substation transformers and ventilate the switchgear. If the temperature is too high, the ventilation and heat dissipation device can be automatically activated.
The temperature signal is measured by the PT 100 thermistor embedded in the hot part of the low-voltage coil. When the load of the dry type transformer increases and the operating temperature rises, the winding temperature reaches a certain value (this value can be adjusted, and Class F dry insulation transformers are generally set at 110 ℃), and the system automatically starts fan cooling. When the winding temperature drops to a certain value (this value can also be adjusted, and the F-level dry insulation transformer is generally set at 90 ℃), the system automatically stops the fan.