The IEC61508 SIL 1 assessed Omni16C Alarm Annunciator from Omniflex is equipped with programmable time delays on input which makes it ideally suited to applications other than straightforward alarming. One such application is in monitoring incoming stream of pulses from any source. The annunciator can be configured to only go into alarm when the pulse stream stops. During normal operation the incoming pulses reset the timer each change of state, ensuring that the timer does not time out. If the pulse stream should stop, the timer will time out, causing that alarm point to go into alarm.
Typical applications include Flow Monitoring and Rotating machinery. The incoming pulses from a proximity switch connected to a rotating shaft can be used to check whether the machine has stopped or is running too slowly. The contact input to the annunciator can be either normally open or normally closed when the machine is in the stopped state. This presents a problem for normal sequences since only one state can be defined as abnormal. However a sequence has been designed to meet this requirement by resetting the timer on each and every change of state so as long as the input continues to change state within the time delay set up on input (defined by the user) the Alarm Annunciator will not go into alarm.
If the rotating machine stops, the changes of state will cease and the timer times out thus bringing up that alarm point on the annunciator. For flow monitoring the standard pulsed output from a flow meter can be input to the Omni16C Alarm annunciator in the same manner as the rotating machinery above, to detect whether the flow has stopped or is too slow. The well proven Omni16C Alarm Annunciator owes its success to various facelifts, upgrades and enhancements over the years and now comes equipped with more features and flexibility than any other annunciator on the market.
