| 摘要 |
PURPOSE:To prevent the occurrence of DC field distortion in a transformer caused by the action of a sunspot by separating the neutral point of the transformer on the side where an expected zero-phase short circuit impedance is higher from the ground to a non-grounded state. CONSTITUTION:By disconnecting either one of earth impedances X1 and X2, a loop constituted of a transformer T1, earth impedance X1, ground E, earth impedance X2, and overhead transmission line L is opened so that no direct current oan be allowed to flow to a system containing the transformers T1 and T2. When the neutral point of one of the transformers T1 and T2 on the side where the zero-phase impedance is higher viewed from a fault point is disconnected, the sound-phase voltage rise which takes place when a single-phase short circuit fault occurs can be reduced. Therefore, DC field distortion which is produced in the transformers T1 and T2 by a direct current flowing through the overhead transmission line L as the terrestrial magnetism fluctuates due to the action of a sunspot can be prevented. |
