Alarm Relays
There are two alarm relays and one fault relay in the Ultima Gas
Monitor. The two alarm relays:
• Activate when the Monitor detects a gas concentration level that
activates Alarms 2 or 3
• Alarms 2 and 3 generally default to 20% and 30% of the
full-scale reading and are set when the gas reading is
above these values.
• The Oxygen Model is a special case where:
• Alarm 2 is set to 18% oxygen and
activates below this setpoint
• Alarm 3 is set to 22% oxygen and
activates above this setpoint.
• These default setpoints can be changed or verified via the
Ultima Controller.
• See Ultima Controller Manual (P/N 813379).
• The Controller can also enable the
latching alarm function.
• Are factory-set to a normally-open position.
• Upon activation, the relay contacts close to provide an
electrical path. These contacts remain closed as long as:
• The alarm condition exists within the Ultima Gas
Monitor or
• The latching mode is selected.
Fault Relay
The Fault Relay differs from the Alarm Relays:
• It is a single-pole, single-throw (SPST) relay.
• During normal operation, the two fault contacts are open.
• When a fault is detected or power is cut or turned OFF, these
two contacts close and provide an electrical path for fail-safe
relay operation. In the event of any failure, including power loss,
the relay will connect its two contacts.
The Fault Relay can remain STEADY ON or PULSED. These two
different modes can communicate different information to any
PLC or DCS connected to the fault relay:
• Fault Relay STEADY ON indicates:
Appendix C, Internal Relay Option
C-5
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