| 摘要 |
PURPOSE:To compensate recharge current with no trouble, even when system voltage is led through bus PT to a current differential relay by making the recharge current compensating function ineffective when a line circuitbreaker is opened and making the compensating function effective when the line circuitbreaker is closed. CONSTITUTION:When a circuitbreaker is opened, a high sensitivity current differential relay 11 is in erroneous operating state '1' and a low sensitivity current differential relay 12 is in non-operating state '0'. Since the output from a timer 13 is '0', output from a relay 12 functions to disable the output from a relay. When the circuitbreaker is closed, recharge current compensation functions normally after a predetermined time (t) later to disable the output from the relay 11. Output from the timer 13 goes to '1' after a predetermined time T later and the output from the relay 11 functions to protect a transmission line with high sensitivity. During this interval, the output from the relay 11 is never employed as the output of the relay. |
