At 18:36 pm on Nov 13, following the issuance of instructions from the dispatching center, the circuit breaker 31322 of the No 5 capacitor in the Taole 220 kilovolt substation in the Shizuishan area was successfully closed, marking the successful commissioning of the first new type of precision phase-controlled switching fast vacuum circuit breaker in China.

As the only 220 kilovolt substation in Taole town and its surrounding areas, the Taole 220 kilovolt substation undertakes the important tasks of power transmission and distribution. In recent years, with the rapid development of the regional economy and the continuous improvement of residents' living standards, the demand for electricity has increased sharply, leading to the increasing daily load of the substation. In particular, the significant increase in the switching frequency of capacitors has put forward higher requirements for the performance of circuit breakers. To this end, the State Grid Shizuishan Power Supply Company has actively responded to the national innovation-driven development strategy and is committed to introducing and applying advanced power equipment to enhance the security and reliability of power grid operations.

The newly introduced 35 kilovolt capacitor's new type of precision phase-controlled switching fast vacuum circuit breaker is based on the contact material prepared from the existing graphene-reinforced copper-based contact material. Compared with traditional circuit breakers, it has achieved significant improvements in arc extinguishing ability, energy storage speed and phase-separated control. It can realize the precision phase-controlled switching of 35 kilovolt reactive power compensation capacitor banks and reduce the electromagnetic transient impact on the system and equipment caused by switching operations. The design of the vacuum double-break enables the circuit breaker to extinguish arcs more effectively during the opening and closing processes, reducing the damage to equipment caused by arcs and extending the service life of the equipment. Meanwhile, the application of the capacitor energy storage technology has replaced the traditional motor energy storage method. It not only improves the energy storage efficiency but also further enhances the response speed and operation reliability of the circuit breaker. Moreover, the circuit breaker also has the function of phase-separated control. This feature enables it to quickly and accurately isolate the faulty phase when a fault occurs in the power system, avoid the expansion of the fault, thus effectively ensure the safe and stable operation of other normal phases. This is of great significance for improving the fault handling ability of the power grid and reducing the risk of power outages.

To ensure the smooth transformation of the equipment, the relevant person in charge of the State Grid Shizuishan Power Supply Company gave directions on-site throughout the whole process and controlled every detail of the maintenance work. Based on regulations and standards and guided by experience and technology, the company comprehensively improved the quality of maintenance. For construction works that required the use of large equipment such as cranes, the company made meticulous arrangements and thorough deployments. It organized relevant staff members to conduct on-site surveys many times beforehand, and also planned the driving routes of cranes as well as its load-bearing landing points. Before starting the work, all staff members were informed of the dangerous points during the on-site construction, the proximity to live electrical conductors and the pre-control measures. Meanwhile, the operation teams strictly implemented the work requirements and formulated standardized construction processes. Workers performed their respective duties, strictly abided by the safety operation procedures and earnestly implemented various safety measures, ensuring the smooth progress of the transformation. With the completion of the transformation of the circuit breaker, the company's maintenance staff members conducted comprehensive inspections and verifications on various performance indicators of the circuit breaker. It was confirmed that the circuit breaker had stable performance and reliable operation and fully met the design requirements.