| 摘要 |
1. A method for the differential protection of electric installations which are the objects to be protected, a) in which method, on both sides of the object to be protected, current signals (I1 , I2 ) are formed as a function of the current flowing through the object to be protected, these currents having identical signals in the direction of flow, b) in which method a differential current signal (DELTA I) is generated from the two current signals and c) as a trigger value, a trigger signal (sa) is generated as a function of this differential current signal, characterised in d) that in each case two successive limit-value comparisons (t1 , t2 ) of the differential current signal (DELTA I) are performed within one half period (H1 , H2 , H3 ) of the measuring current, e) that the trigger signal (sa) for one trigger section (AS) is generated as a function of a dual limit-value transgression (t1 , t2 ) of the differential current signal (DELTA I) within one half period of the measuring current, and f) the blocking function is actuated within the subsequent half period of the measuring current if only one limit value transgression (t2 ) of the differential current signal (DELTA I) occurs. |
