The system consists of one or several pressure contacts (connected in series), a control unit (alarm unit AG 10 Ex) and, if required, an additional alarm unit. If several contacts are to be monitored, the corresponding number of electrical contacts can be connected in series and monitored by a single alarm unit. It is also possible to connect a separate alarm unit for each measuring point. An alarm is triggered when the contact opens. An event reporting system can be connected to the relay output of the alarm unit for remote monitoring.
The alarm signal is generated by a pressure gauge with an electrical contact. The alarm threshold can be set to any value from 5 to 95 % of the range by means of the contact arm of the pressure gauge. A green LED indicates normal operation. In case of a power outage, the device does not generate an alarm signal; when power becomes available again, the unit immediately resumes operation. If, in the meantime, the gas pressure has fallen below the set limit, an alarm signal is generated. In the case of an alarm, the red LED lights up; in addition, the system generates an audible alarm. The audible alarm can be acknowledged. The red LED remains lit. The alarm can also be configured for fail-safe mode so that an alarm can also be triggered in the case of a power outage. Proper operation of the system can be checked at all times by means of pressing the Test key. If this button is pressed, the system generates an alarm, i.e. the red LED lights up and the audible alarm sounds.