In order to ensure the service life of the oil immersed type transformer, the circuit must be protected. Here are some introductions of the oil immersed type transformer from the manufacturers: as long as the oil-immersed transformer circuit does not have any problems during its operation, the use and life of the transformer can be guaranteed. Next, let's take a look at the circuit protection of oil-immersed transformers.
For the main transformer of the workshop substation with the high voltage side of 6-10KV, it is usually equipped with over-current protection with time limit. If the time of the over-current protection action is greater than 0.5-0.7s, the current quick-break protection should also be installed. For the oil-immersed type transformer with a capacity of 800KV · A and above and the oil-immersed type transformer in a workshop of 400KV · A and above, gas protection shall be installed as required.
For the transformers with a capacity of 400KV · A and above, when several units are operated at the same time or in a single operation and used as a backup power source for other loads, overload protection should be installed according to the possible overload conditions. Overload protection and gas protection act on the signal when there is a slight fault, while the other protections, including the gas protection, generally act on the trip when there is a serious fault.
For the main transformer of the plant's total step-down substation with a high voltage side of 35KV and above, overcurrent protection, current quick-break protection and gas protection should also be installed. When there is a possibility of overload, overload protection should also be installed. However, if the capacity of a single-operation transformer is 10000KV · A and above and the capacity of each transformer at the same time is 6300KV · A and above, it is required to install the longitudinal differential protection to replace the current quick-break protection.