| 摘要 |
PURPOSE: An adaptive reclosing of momentary voltage drop is provided to reduce the probability of the occurrence of a momentary voltage drop and thus to reduce the damage on the electronic device due to the voltage drop. CONSTITUTION: In the adaptive reclosing method of momentary voltage drop, in step 1, the device detects an overcurrent(Ioc) from the overcurrent relay and detects a ground current(Ig) from the ground current relay. In step 2, if both the overcurrent(Ioc) and the ground current(Ig) are smaller than the reference overcurrent(Isoc) and the reference ground current(Isg) respectively, the procedure moves to step 3. But if either the overcurrent(Ioc) is bigger than the reference overcurrent(Isoc) or the ground current(Ig) is bigger than the reference ground current(Isg), the procedure moves to step 4. In step 3, the operation remains normal. In step 4, the circuit breaker is tripped. In step 5, if the fault voltage(Vf) is bigger than or equals to the first reference voltage(Vld1) the procedure moves to step 6. But if the fault voltage(Vf) is smaller than the first reference voltage(Vld1), the procedure moves to step 7. In step 6, N+1 times of reclosing are conducted. Here, the N is the reference number of times for reclosing. In step 7, if the fault voltage(Vf) is bigger than or equals to the second reference voltage(Vld2), the procedure moves to step 8. But if the fault voltage(Vf) is smaller than the second reference voltage(Vld2), the procedure moves to step 9. In step 8, if the fault is one phase accident, the procedure moves to step 9. But if the fault is not an one-phase accident, the procedure moves to step 10. In step 9, N times of reclosing are conducted. In step 10, N-1 times of reclosing are conducted.
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