| 摘要 |
In order to monitor circuits for an overload, especially circuits in which the short-circuit current is limited (e.g. generator circuits in mains-standby systems), a threshold value switch (ZD, S) is provided, which is coupled to the load circuit via current transformers (W1, W2, W3) having loads (R1, R2, R3) connected downstream from them, which threshold value switch trips in the event of an excess current which is considerably higher than the rated current and breaks the supply lines (L1, L2, L3) to the loads, via a contactor. Any desired number of circuits can inherently be monitored by using a plurality of such threshold value switches for individual circuits or a sequencing circuit. By allocating different time constants to the individual threshold value switches, a specific sequence for disconnecting the circuits in the event of a disturbance can be predetermined. The circuit is suitable for monitoring both single-phase and multi-phase networks and reacts to single-phase or multi-phase short-circuits in the same manner. <IMAGE>
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