| 摘要 |
PURPOSE:To realize protection as much as possible even if a ground-to-line fault is caused by detecting an open-phase condition of the lead phase for the investigation object phase to lower the degree of compensation of zero-phase compensation of a ground-to-line fault distance relay when the lead phase is missed and to fix the degree of compensation in other cases. CONSTITUTION:The self line and adjacent line disconnecting condition is introduced in the step 1 through I/O. Moreover, when a circuit breaker for the adjacent line of lead phase is opened for the predetermined investigation object phase, a degree of compensation of zero-phase compensation by the adjacent line is changed to the fixed value K'o2 which is smaller than the predetermined value Lo2. When the adjacent line circuit breaker is closed, a degree of compensation is returned to the predetermined value Ko2 in the step 2. In the same manner, when the circuit breaker for self line of lead phase is opened for the predetermined investigation value, a degree of compensation Ko1 of the zero-phase compensation of the self line is changed to the fixed value K'o1 which is smaller than the predetermined value. Meanwhile, if the circuit breaker is closed, a degree of compensation is returned to the predetermined value in the step 3. A current value for calculation is obtained in the step 4 depending on determination in each step. Thereby, malfunction of the sound phase can be prevented. |
