TThere are 4 main transformers in the first phase of No. 1 power plant, which are # 1-#4 generator step-up transformers, and the connection way with generators is unit wiring. The generator outlet voltage is 6. 3 kV, which is directly connected with the 6 kV plant system to supply power. The generator and plant system consist of a small current grounding system. When the system occurs single-phase grounding, the size and phase of each phase still remain unchanged, and the balance of the three-phase system has not been destroyed, so the short time operation is not allowed to find the fault point, which is suitable for the 6 kV plant system. However, if the connection place is on the side of the generator, the fault current of the generator is the sum of the capacitance current of all lines of the 6 kV plant and the capacitor current of the generator. If not taking measures in a short time, the generator stator coil will be burned down and the insulation breakdown and other major injuries will be destroyed.%一电站一期共设4台主变,做为#1-#4发电机的升压变压器,与发电机连接方式均为单元式接线.发电机出口电压均为6.3 kV直接与6 kV厂用系统相连为其供电,发电机与厂用系统共同组成了小电流接地系统.当此系统发生单相接地时,各相间电压大小和相位仍然不变,三相系统的平衡没有遭到破坏,故不跳闸允许短时运行以便查找故障点,这适合于6 kV厂用系统.但如接地点在发电机侧,则发电机所承受的故障电流为6 kV厂用系统所有线路电容电流与发电机电容电流的总和,如不在短时间内采取措施势必会烧毁发电机定子线圈、造成绝缘击穿等重大伤害.
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