大型发电机中性点接地装置的研制

我国大型发电机机电设计中，大多数中性点接地一直沿袭传统的消弧线圈接地方式，这种接地方方式虽可广泛的应用，但调谐要求高，存在着单相接地时电机扩大故障的威胁，而采用带二次负载变压器装置的接地方式虽可能受电网容量的限制，但对电机保护更为可靠，更具优越的技术经济特性。通过对二种接地方式的比较，结合隔河岩３号、４号发电机中性点带二次负载变压器接地装置的研制和运行、试验成果进行分析，表明该装置安全可靠、效果明

Development of neutral earthing devices for large generators

In design of large generators in China, the way of neutral earthing has been adopting the conventional one of arc extinguishing coil. Although this earthing way may be used extensively, it requires strict tuning, and when it is used for single phase earthing,there exists threat of spread generator fault. A ground device with secondary load transformer can more effectively protect a generator, and has superior characteristics of technology and economy, but would be limited by the the capacity of electric network. Through compatison between above both ground ways, it is decided that the latter is adopted as ground devices for Geheyan Hydropower Station No. 3 and No. 4 generating units. Testing results show that this device is reliable, and more beneficial to protecting the isolators in a generator. No. 3 and No. 4 generating units have been in operation successfully. In addition, selection of the ground transformer, the loaded resistance and their main parameters are also presented, which is available to designing a similar power station for reference.