| 摘要 |
PROBLEM TO BE SOLVED: To stabilize a reverse-phase current to be injected into a system, and to prevent the return of grounding current by suppressing the grounding current by a supplied antiphase current. SOLUTION: When a grounding fault occurs, the phase voltages of bus-bars 3a-3c becomes unbalanced, and a zero-phase sequence voltage V0 is detected in a zero-phase sequence transformer, and zero-phase sequence current I02 I03 are detected by the zero-phase sequence current transformer 7b, 7c of distribution lines 5a-5c, 6a-6c. The zero-phase sequence current transformer 7a of distribution lines 4a-4c detects a resultant current Ig2 of grounding resistance component currents Ira, Irb, Irc from the grounding neural liens of the zero-phase sequence current transformers, and the zero-phase sequence currents I02 I03 detected by the zero-phase sequence current transformers 7b, 7c. From the detected zero-phase sequence voltage V0, zero-phase sequence currents I02 I03 and resultant current Ig2, a grounding fault detector 10 decides that a grounding fault occured. Consequently, a grounding current can always be suppressed stably without returning it, and to obtain in a grounding suppressing system which facilitates extinction of a grounding arc.
|
