Monitoring device for DC circuit - uses limit value alarm with circuit voltage applied to its input

摘要

Two fault alarms are used, one (S1) for a lower limit (U1) and the other (S2) for the upper limit (U2) of the monitored voltage (U0). Three stores (Y1-Y3) are provided. First store (Y1) dynamic setting input (T1) is connected to the output of the first alarm (S1) also connected through an invertor (N1) to the dynamic setting input (T3) of the third store (Y3). The dynamic setting input (T2) of the second store (Y2) is connected through an invertor (N2) to the output of the second alarm (S2). Similar outputs (Y2-N, Y3-N) of the second (Y2) and third (Y3) stores are disjunctively linked with each other through a NOR gate (V) and connected to the resetting input (R1) of the first store (Y1). Its output (Y1-P) is the circuit output (A).