| 摘要 |
1. Protection device of an electric equipment from a power arc sticken along a bar system (12) of the equipment, said device comprising an arc detecting member capable of sending, in case of arc fault, a tripping order to a breaking device (14) located above the fault, wherein the arc detecting member is formed by an electronic relay (20) comprising : - means of analysis of the alternating voltage U present between the conductors of the bar system (12), - analogic means of the fault discrimination sensitive to the change of the U voltage form and generating a control signal when the high temporary derivative of the U voltage exceeds a predetermined value, - and means to process the control signal for building up the tripping process following the appearance of an arc fault, characterized in that said analogic means of the fault discrimination comprise a filtering circuit (28) associated with a threshold gate (30), which is connected to a transformation circuit (32) cooperating with a logic processing circuit (34) playing a role in the elaboration of the tripping process by assuring the distinction between a temporary incident and a real arc fault, said processing circuit (34) comprising : - members of time-lag constituted by a first (36) and a second (38) monostable trigger circuit, each receiving the output of the transformation circuit (32) and remaining in the logic state 1 during predetermined time-lags respectively T1 and T2, when a first pulse is generated by the transformation circuit (32), the time-lag T2 of the second monostable trigger circuit (38) being above the one T1 of the first monostable trigger circuit (36), - a first bistable trigger circuit (40) controlled by the transformation circuit (32) and by the second monostable trigger circuit (38) so that the passage of the output of the first bistable trigger circuit (40) to the logic state 1 happens when the transformation circuit (32) emits a second pulse and so that the output of said first bistable trigger circuit (40) is automatically reset to the logic state 1 at the end of the time-lag T2, - a second bistable trigger circuit (42) controled by the transformation circuit (32) and by the output of a logic gate AND (46) receiving the outputs of the first monostable trigger circuit (36) and of the first bistable trigger circuit (40), the processing circuit (34) being accommodated to deliver the tripping order after the emission of three pulses by the transformation circuit (32), the third pulse of the transformation circuit (32) having obligatorily to happen during the time-lag T2 of the second monostable trigger circuit (38) and after the end of the time-lag T1 of the first monostable trigger circuit (36). |
