| 摘要 |
The invention relates to a method for the digital monitoring of current or voltage states, particularly for monitoring the heating current on rail vehicles, in which an error message is output after a fault or an interruption. To implement the detection of a current drop independently of the variation with time and the type of the current in a much more noise-insensitive manner and to allow a fault indication to take place only after the current drops below a threshold value beyond a minimum time, the following is proposed according to the invention: a drop in current is registered by a monostable flip flop (5); the output pulse of the latter simulates the current to be monitored over a defined adjustable bridging time and an error message is only output when this bridging time is exceeded. The current drop is converted into a digital signal of a particular level and corresponding duration. This digital signal activates, on the one hand, the monostable flip flop (5) and its duration is compared, on the other hand, with the pulse duration of the monostable flip flop (5) in a logical OR gate and when the duration of the digital signal exceeds the pulse duration of the flip flop, a bistable store (9) is set for outputting a fault message. <IMAGE>
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