The duration of symmetrical short-circuit current of dry-type transformer during operation: during the inspection, the inspector mainly checked the electroscope, grounding wire and protection of each construction unit, and strengthened the sense of responsibility. When the application department did not put forward other requirements, the duration of current I used to accept short-circuit heat resistance ability was 2S.
The double channel power supply station of dry-type transformer is used correctly to guide the outsourcing construction team on how to correctly protect and check. When two such transformers are in parallel operation and the low-voltage side bus fault occurs and the section switch at this side jumps off, the possible short-circuit current in the low-voltage winding of the transformer can reach 0.75 times the standard value, which is nearly 50% higher than the planned value.
Because most of the 500kV dry-type transformers are single-phase transformers, the dry-type transformer body will not have interphase faults. In the high and medium voltage system connected by the transformer, the line protection is generally equipped with two layers of longitudinal protection, and the materials are consistent; check whether each construction team is equipped with qualified safety tools and test cycle according to the rules; Check whether the person in charge of the work and the technicians grasp and promote the project construction orderly, and have complete backup protection, so that the fault of the line will be removed quickly, and the impact on the dry-type transformer is small. Therefore, the phase to phase backup protection of dry-type transformer should mainly work in case of bus fault on each side, especially on the medium and low-voltage side.
The high short-circuit current flowing through dry-type transformer caused by medium and low-voltage bus fault not only causes overheating of dry-type transformer winding, but also may cause dynamic stability damage of winding, and cause severe internal problems. Besides, it is not allowed to eliminate potential safety hazards to ensure the safety of personnel, equipment and power grid.
No matter how to protect the dry-type transformer, we are adhering to how to ensure the safe operation of dry-type transformer in daily operation and reduce the occurrence of some losses. Therefore, the technical personnel are also more cautious and expect the future dry-type transformer to be better and better in the market development.
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