About pressure relief valves

Due to the limitations of the upper structure of the transformer oil tank, the pressure relief valve is usually installed around the top cover, as close as possible to both ends of the tank, and can be installed at any position between the iron core and the winding. This installation can ensure effective oil leakage after the pressure relief valve works. When the pressure relief valve is installed directly above the winding, if the pressure of the winding is not enough, when an external short circuit occurs, the coil of the winding will be subjected to a strong current, forming a shock wave. If the pressure relief valve is installed directly above the magnetic leakage channel at this time, the pressure relief valve will act first. The shock wave generated by short-circuit current is generally small. If the external fault disappears, the oil pressure of the pressure relief valve will also disappear, and the pressure relief valve will automatically return to its original working state. Usually, pressure relief valves for larger transformers are installed at both ends of the transformer.

Necessity

Firstly, the pressure relief valve is an important protective device for transformers, and its misoperation or refusal to operate can have a significant impact on the safe and reliable operation of transformers. When there is a fault inside the transformer (such as overheating, short circuit, breakdown, etc.), the transformer oil expands and the abnormal pressure inside the transformer must be discharged, otherwise it will cause serious deformation and explosion of the oil tank, resulting in serious accidents. Secondly, after years of operation, especially under harsh conditions, the pressure relief valve may damage its seal and reduce its insulation performance. If this type of pressure relief valve continues to operate, it is prone to leakage, false alarms, or refusal to operate. In addition, the quality of pressure relief valves produced by different suppliers varies greatly, and choosing a pressure relief valve manufacturer cannot be ignored. Therefore, strengthening the supervision of pressure relief valve calibration and strictly controlling the calibration is a very important task.

proposal

1. Strengthen the inspection of pressure relief valves entering the network

2. Strengthen the inspection of pressure relief valves during operation:

Before the pressure relief valve was put into use in the early stages of our country, it did not undergo any inspection work, which directly led to some products that did not meet the quality requirements being hung on the power grid for use. At the same time, after years of operation, especially in some extremely harsh operating environments, the sealing ring and insulation performance of these unqualified pressure relief valves will significantly decrease. From the relevant inspection results, the pressure relief valves with quality degradation mainly show problems such as unqualified opening pressure, air leakage, and unstable insulation. If such products are still used for operation, not only will there be phenomena such as refusal to operate, false alarms, and leakage, but it is also highly likely to lead to unplanned failures, which not only affect power supply but also cause significant losses to power companies. To solve these problems, it is necessary to combine them with the overhaul work of transformers, and ensure their safe operation through more comprehensive pressure relief valve detection work.

3. Pay attention to the selection of pressure relief valve suppliers:

In the process of purchasing pressure relief valves, power companies must compare the quality of goods. Pressure relief valves produced by different manufacturers actually have significant differences in product quality. Especially during the stage of signing the corresponding technical agreement, it is necessary to fully confirm that several basic elements such as the brand, price, and quality of the pressure relief valve fully meet the needs of the power grid.

4. Prepare sufficient spare parts:

Due to the low inspection qualification rate and satisfaction level of the transformer pressure relief valve itself in actual use, it is necessary to prepare spare parts for its pressure relief valve to prevent engineering operation failures or frequent major repairs caused by the unqualified effectiveness of the pressure relief valve.