Stand-by current monitor for alarm in electrical circuit - has monitoring circuit which allows reset of circuit to prevent reactivation of alarm indicators

摘要

The monitoring arrangement is for an alarm system and maintains a check on the quiescent current in alarm connecting lines to ensure that false triggering does not occur. In particular, the system avoids problems associated with an increase in voltage following an alarm state cancellation, where the alarm indicator, e.g. flasher can be re-activated. A number of feed units (ES1 to ESn) are used to control the triggering of alarm units to produce activation of the flashing display. As soon as the voltage from the mains (NT) falls below a specified value, the triggered alarm drops out and a control signal (LS) is detected by the monitoring stage (US). As soon as the supply voltage begins to rise, the alarm indicator is activated once more. This may be prevented by operating a reset (RT).