The safe operation of power transformers relies on a complete protection mechanism. Large-scale power transformers are equipped with both electrical and non-electrical quantity protections. When electrical quantity protection fails to deal with certain faults, non-electrical quantity protection becomes crucial for ensuring the safety of the main transformer. For example, gas protection serves as the main protection against internal faults. The gas relay plays a significant role in gas protection, and its operation and maintenance involve multiple key points such as gas discharge, circuit connection, and performance verification.
The temperature of the cooling medium and windings of the transformer must be strictly controlled, which is achieved by relying on the temperature controller. The temperature controller includes the oil surface temperature controller and the winding temperature controller. Among them, the oil surface temperature controller measures the temperature by utilizing the characteristics of the temperature-sensitive liquid and regulates the cooling system, and the measured values can be displayed remotely. Dual oil surface temperature controllers are often configured for large-scale transformers. In addition, the setting of connecting the contacts of the temperature controller to the trip circuit needs to comprehensively consider the structure of the transformer and the duty mode of the substation, and the trip signal should use hard contacts to prevent the misoperation of the non-electrical quantity protection.